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24AA02E48-I/OT - 2Kb I2C EEPROM with EUI-48 MAC | Microchip
The Microchip Technology 24AA02E48-I/OT is a 2-Kbit (256 x 8) I2C serial EEPROM with a factory-programmed EUI-48 MAC address, organized as two 128 x 8-bit memory blocks and housed in a 5-lead SOT-23 package. The device operates from 1.7 V to 5.5 V with a maximum standby current of 1 uA and a maximum active (read) current of 1 mA, and it supports a 2-wire (I2C) bus at clock rates up to 400 kHz with 900 ns access time. An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory that retains data without power and supports byte-level, in-circuit rewrites through a serial protocol. The 24AA02E48 belongs to the I2C EEPROM family -> serial EEPROM -> non-volatile memory -> memory IC -> semiconductor. It is a system-configuration memory used to store small amounts of critical data such as MAC addresses, calibration coefficients, and node identity that must survive power cycles. Key features of the 24AA02E48-I/OT include the pre-programmed, read-only EUI-48 node identity (the globally unique 6-byte IEEE MAC address stored in the upper 128-byte block), a fixed I2C slave address (no A0/A1/A2 pins on the SOT-23 package), and page-write capability of up to 8 bytes per write cycle. The wide 1.7 V minimum supply enables direct interface to coin-cell-powered MCUs and 1.8 V SoCs without level shifting. Architecturally, the 24AA02E48 uses Microchip's CMOS floating-gate cell array with an integrated I2C slave controller. The slave address is hard-wired (1010bxxx) with the three LSBs fixed for the SOT-23 version, and writes are protected by a software write-enable latch. ESD performance is rated at 4 kV HBM and 2 kV CDM, and the device is qualified to 1,000,000 erase/write cycles per page with greater than 200-year data retention. Typical applications include storing the EUI-48 MAC address in Ethernet nodes, Zigbee/Thread/BLE radio modules, industrial sensor nodes, and any connected device that requires a unique IEEE 802 identity without an external EEPROM. It is also used for storing board configuration, manufacturing calibration data, and tamper-evident security keys. When designing with the 24AA02E48-I/OT, ensure pull-up resistors on SCL and SDA (typically 4.7 kohm for 5 V and 10 kohm for 1.8 V) and respect the 30 ms maximum write cycle time. Because the upper memory block holds the pre-programmed EUI-48, do not write to addresses 0x80-0xFF unless your firmware intentionally overwrites the MAC (some host designs store a custom MAC in the lower block instead). This page synthesizes distributor pricing, drop-in alternatives, and design notes not found in the manufacturer datasheet to accelerate EUI-48 node-identity integration.
24AA02E48T-I/OT - 2Kb I2C EEPROM with EUI-48 MAC | Microchip
The Microchip Technology 24AA02E48T-I/OT is a 2-Kbit I2C-compatible serial EEPROM with a factory-programmed, globally unique EUI-48 node identity, housed in a 5-pin SOT-23 package. The device is organized as two blocks of 128 x 8 bits, supports a 400 kHz clock rate with 900 ns access time, and operates from 1.7V to 5.5V with maximum standby and active currents of only 1 uA and 1 mA respectively. A serial EEPROM is a non-volatile memory that uses a simple two-wire (I2C) protocol to store small amounts of configuration data, calibration constants, or identity information that must survive power cycling. In the component hierarchy it sits under EEPROM -> non-volatile memory -> memory IC -> semiconductor. The integrated EUI-48 node address turns this device into a drop-in Media Access Control (MAC) identity source for Ethernet, Wi-Fi, Bluetooth, IEEE 802.15.4 and other networking nodes, eliminating the need for an external MAC allocation scheme. Key features include software write protection for the upper 128 bytes, a hardware write-protect pin for full-array protection, page write capability of up to 8 bytes, and 1 million erase/write cycles endurance with greater than 200-year data retention. The 5-pin SOT-23-5 footprint (package code OT) is one of the smallest I2C EEPROMs available, making it ideal for space-constrained designs. The 'E48' suffix denotes the pre-programmed EUI-48 MAC address; the standard 'I' industrial grade covers -40C to +85C. The 24AA02E48 uses a CMOS process with on-chip ECC-style reliability and a low-power design. Up to eight 24AA02E48 devices may share the same I2C bus through hardware address bits. Because the MAC is factory programmed and locked, every unit ships as a unique node, allowing designers to skip manual MAC allocation or OTP burn-in at production. Typical applications include IoT sensor nodes requiring a unique MAC address, industrial automation modules, smart-meter communication boards, Bluetooth/Wi-Fi companion identification, and any embedded design that needs a tiny, low-power identity store. It is also used for storing configuration, calibration constants, and tamper-resistant settings in consumer devices. When designing with the 24AA02E48, place a 100 nF decoupling capacitor close to VCC and respect I2C pull-up values per the bus specification. Because the EUI-48 is factory-locked, do not attempt to rewrite the unique-address region (upper 128 bytes) - that block is software-protected by design. This page synthesizes verified distributor pricing, SOT-23-5 drop-in alternatives, and practical design notes that go beyond what is found in the Microchip datasheet (document 20002124H) alone.
24AA16-I/SN - 16Kbit I2C EEPROM, 1.7V-5.5V, 400kHz | Microchip
The Microchip Technology 24AA16-I/SN is a 16-Kbit (2K x 8) I2C-compatible serial EEPROM organized as eight blocks of 256 x 8-bit memory with a two-wire serial interface, housed in an 8-pin SOIC (SN) package. It operates from a wide 1.7V to 5.5V supply voltage, supports a maximum clock frequency of 400 kHz, and delivers access times as low as 900 ns. A serial EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory device that communicates with a host microcontroller through a small pin count serial protocol, retaining data without power. EEPROM belongs to the broader non-volatile memory family alongside Flash and ROM, but is byte-erasable, ideal for storing small, frequently updated configuration parameters. Within a system hierarchy, the 24AA16 functions as a memory IC > EEPROM > serial EEPROM > I2C EEPROM > non-volatile memory > semiconductor, commonly used to store user settings, calibration data, and device IDs. Key features include a low standby current of 1 uA (typical) and active read current of 1 mA, hardware write-protection capability through the WP pin, and a page write buffer that supports up to 16 bytes of data per write cycle. The 24AA16-I/SN operates across the industrial temperature range of -40C to +85C and supports a minimum of 1 million erase/write cycles with data retention of more than 200 years. The 24AA16 uses CMOS technology and is offered in three speed grades: the 24AA16 (1.7V-5.5V, 400 kHz), the 24LC16B (2.5V-5.5V, 400 kHz), and the 24FC16 (1.7V-5.5V, 1 MHz). The I2C interface supports standard (100 kHz) and fast (400 kHz) modes, and the device is hardware-compatible with industry-standard I2C bus specifications. The eight 256-byte blocks enable block-write protection and selective data updates. Typical applications include consumer electronics for storing user preferences, industrial control for calibration constants and serial numbers, medical devices for patient data and device configuration, automotive accessory modules, and smart metering. It is well-suited to IoT endpoints that need persistent parameter storage with low standby current. When designing with this device, place a 0.1 uF decoupling capacitor close to the VCC pin and respect the maximum I2C bus capacitance. The WP pin can be tied low or high to enable or disable write protection; leaving it floating risks accidental write-lock state. This page combines verified distributor pricing, drop-in alternatives, and practical design notes that are not found in the manufacturer datasheet alone, giving procurement and engineering teams a single decision-ready reference for the 24AA16-I/SN.
24AA256-E/SN - 256Kbit I2C EEPROM, 1.7-5.5V, 8-SOIC | Microchip
The Microchip Technology 24AA256-E/SN is a 256-Kbit (32K x 8) I2C-compatible 2-wire serial EEPROM organized as 32,768 x 8 bits, with a maximum clock frequency of 400 kHz and a 900 ns access time, housed in an 8-pin SOIC (SN) package. The "-E" suffix denotes the Extended temperature grade (-40C to +125C), distinguishing it from the industrial-grade "-I" variant (-40C to +85C), and the device supports an operating voltage range of 1.7V to 5.5V across the entire temperature range. An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory that retains data when power is removed and supports byte-level or page-level in-system rewriting. The 24AA256 belongs to the serial EEPROM hierarchy (serial memory -> non-volatile memory -> memory IC -> semiconductor), and uses the industry-standard I2C (Inter-Integrated Circuit) two-wire bus originally developed by Philips. Serial EEPROMs are preferred over parallel EEPROMs in space-constrained designs because they require only two signal lines (SCL clock + SDA data) instead of 8 to 32 address/data lines, dramatically reducing GPIO count on the host microcontroller. Key features of the 24AA256-E/SN include hardware write protection via the WP pin, a 64-byte page write buffer for efficient multi-byte writes, built-in 32-byte page write modes, and 1 million erase/write cycles endurance with greater than 200-year data retention. The device supports both byte-level random reads and sequential reads, and the dedicated Write Protect (WP) pin allows the upper quadrant of memory to be hardware-locked against inadvertent writes - useful for storing firmware parameters that must not be overwritten during field updates. The 24AA256 family uses CMOS process technology with low standby current (typically 100 nA) and active read current (typically 1 mA at 400 kHz), making it well-suited for battery-powered applications. The internal organization is 512 pages of 64 bytes each. Address lines are multiplexed onto the I2C bus through three hardware-selectable device address bits (A0, A1, A2), allowing up to eight 24AA256 devices to coexist on a single I2C bus for a combined 2 Mbit of addressable non-volatile storage. Typical applications include personal communications devices, data acquisition systems, industrial controllers storing calibration coefficients, smart meters with non-volatile event logs, automotive body modules using the extended temperature grade, and consumer electronics holding user preferences. The wide 1.7V to 5.5V supply range allows direct connection to single-cell Li-ion batteries (3.0V to 4.2V) as well as standard 3.3V and 5V rails. When designing with the 24AA256-E/SN, place a 100 nF decoupling capacitor close to the VCC pin and route the SDA/SCL lines away from noisy switching nodes. Pull-up resistors on SDA and SCL (typically 4.7 kohm at 5V or 10 kohm at 3.3V) are required because the EEPROM uses open-drain I/O. Observe the 5 ms maximum write cycle time when calculating endurance and worst-case throughput. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found on the manufacturer datasheet alone, including an explicit comparison with the industrial-temperature 24AA256-I/SN and the higher-throughput 24FC256 family.
24AA256-I/SN - 256Kbit I2C EEPROM, 400kHz, 1.7-5.5V | Microchip
The Microchip Technology 24AA256-I/SN is a 256-Kbit (32K x 8) serial Electrically Erasable PROM (EEPROM) operating over a broad 1.7V to 5.5V supply range with a 2-wire I2C-compatible interface up to 400 kHz, housed in an 8-pin SOIC (SN) package. It is offered in the industrial -40C to +85C temperature grade with a 900 ns typical access time and supports 64-byte page writes for efficient bulk programming. A serial EEPROM is a non-volatile memory device that retains data through power cycles and is written/read serially over a low-pin-count bus such as I2C, SPI, or Microwire. EEPROMs sit within the non-volatile memory hierarchy alongside Flash and FRAM, sitting beneath NAND/NOR Flash in write endurance but above Flash in random-access byte-level write granularity. The 24AA256 belongs to the broader EEPROM family -> non-volatile memory -> memory IC -> integrated circuit taxonomy, and is a drop-in member of Microchip's 24XX256 I2C EEPROM series. Key features include hardware write-protect via the WP pin, software data protection via a special 4-bit sequence to prevent inadvertent writes, and >1 million erase/write cycles per byte with >200-year data retention. The 24AA256 operates at very low standby current (typically 1 uA) and read current (typically 1 mA), making it ideal for battery-powered designs where minimizing quiescent drain is critical. The device uses a CMOS process with a built-in Schmitt trigger on the SCL/SDA inputs for noise-tolerant bus operation, plus a cascadable 3-bit hardware address scheme (A0, A1, A2) that lets up to eight devices share the same I2C bus without bus contention. Random and sequential read modes both supported. The architecture is optimized for low-power, low-density non-volatile storage rather than high-throughput logging. Typical applications include storing user preferences in consumer electronics, configuration parameters in industrial control modules, calibration constants in test and measurement instruments, and black-box event logs in portable medical devices. The wide voltage range supports direct attachment to 1.8V, 3.3V, and 5V rails without level shifters. When designing with this part, add proper I2C pull-up resistors (typically 2.2-10 kohm depending on bus capacitance and speed) on SCL and SDA. Reserve a 5 ms write-cycle time per page-write operation in firmware to avoid polling hazards, and tie WP low only if write protection is not needed; tying WP high freezes the memory map. This page synthesizes distributor pricing, drop-in same-package alternatives (24LC256, 24FC256, AT24C256C), and practical design notes not found in the manufacturer datasheet.
24AA256UID-I/SN - 256Kb I2C EEPROM w/ EUI-48/EUI-64 | Microchip
The Microchip Technology 24AA256UID-I/SN is a 256-Kbit (32K x 8) I2C serial EEPROM with factory-pre-programmed EUI-48 and EUI-64 IEEE MAC addresses plus a 32-bit unique serial number, housed in an 8-pin SOIC (SN) package. It operates from 1.7V to 5.5V (Microchip datasheet 20005215D cites 1.8V to 5.5V in product brief, with 1.7V min in datasheet electrical tables) and supports up to 400 kHz I2C clocking at 900 ns access time, making it compatible with both standard and fast-mode I2C controllers. An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory that retains data without power and supports byte-level in-system rewrites, typically used for configuration, calibration constants, and identity records. The 24AA256UID belongs to the broader hierarchy: serial EEPROM -> non-volatile memory -> memory IC -> semiconductor. Compared with Flash, EEPROM offers finer write granularity (byte vs page/sector) at lower write-cycle endurance cost; compared with EPROM, it is in-system programmable without UV erasure. Key features include 256 Kbit density organized as 32K x 8, 64-byte page write buffer, hardware write-protect pin, sequential read capability, low standby current typically 1 uA, and automotive AEC-Q100 qualification. The factory-programmed EUI-48 / EUI-64 node identity and 32-bit Unique ID let designers drop in IEEE 802 MAC addresses and OEM serial numbers without provisioning at the programming station - a major BOM and process simplification for networked sensors. The 24AA256UID-I/SN uses a standard two-wire I2C interface with three address pins (A0/A1/A2) supporting up to eight devices on one bus. Internally it provides 32K bytes of user EEPROM plus the locked upper 1/8th of the array holding the 32-bit serial number and EUI blocks; writes to that region are permanently write-protected at the factory. Typical applications include IoT and industrial sensor node identity, Bluetooth/Wi-Fi MAC address provisioning, asset tracking tags, metering and instrumentation that must carry a globally unique serial number, and automotive sub-systems where AEC-Q100 is required. It is also used as a low-cost parameter/calibration store behind small microcontrollers lacking internal NVM. Design considerations: the unique ID / EUI region is locked at the factory, so for variants requiring customer-programmed IDs use the standard 24AA256 (no UID suffix) instead. Operating voltage from 1.7V to 5.5V lets the part ride on 1.8V, 2.5V, 3.3V, or 5V rails without level shifters. This page synthesizes Microchip datasheet specifications, distributor pricing tiers, drop-in pin-compatible alternatives, and practical design notes - distinct value beyond the bare datasheet.
24AA256UIDT-I/SN - 256Kb I2C EEPROM with EUI-48/64 | Microchip
The Microchip Technology 24AA256UIDT-I/SN is a 256 Kbit (32K x 8) I2C serial EEPROM with factory-pre-programmed globally unique EUI-48 and EUI-64 IEEE MAC addresses plus a 32-bit unique serial number, offered in an 8-pin SOIC package. It operates across a broad 1.7V to 5.5V supply range, supports 400 kHz Fast Mode I2C clocking, and delivers 900 ns access time. The "T" suffix denotes Tape & Reel packaging. A serial EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory hierarchy member that retains data after power removal, sits below Flash in density, and offers byte-level endurance over millions of write cycles. Within the Microchip 24XX family, the 24AA256UID occupies the upper-density 256 Kbit tier with the unique addition of pre-burned MAC/unique-ID fields, eliminating the need for host firmware to provision IEEE addresses during manufacturing. Key features include 64-byte page write capability, hardware write-protect pin support via the WC input, low standby current of typically 1 mA maximum, and read current of 1 mA typical at 5.5V. Endurance is rated at 1 million erase/write cycles per byte with data retention greater than 200 years. The device supports a 128-byte write page in firmware-emulation mode and operates across the industrial temperature range of -40C to +85C. I2C addressing is hardwired across the A0, A1, A2 pins, allowing up to eight devices on a single bus. The 24AA256UIDT-I/SN uses a CMOS floating-gate process with on-chip charge pump for byte/page write operations, and integrates proprietary EUI-48 and EUI-64 node address registers at factory-programmed fixed locations. The unique ID register holds a 32-bit serial number that, when combined with the EUI-64 value, provides a complete IEEE 802-compliant node identity without external provisioning. Typical applications include industrial sensor nodes, IoT endpoint devices that require a globally unique MAC address for network registration, IPv6/6LoWPAN nodes, asset tracking tags, building automation modules, and medical device identification. The combination of MAC address pre-programming and small SOIC footprint makes it ideal for compact, cost-sensitive connected products. When designing with this part, ensure the I2C bus pull-ups are sized for the 400 kHz clock rate with the maximum bus capacitance, and verify that the host microcontroller's I2C controller supports both standard 100 kHz and Fast Mode 400 kHz operation. Always check the read/write protect logic before enabling multi-master bus arbitration. This page consolidates distributor stock and pricing, lists Microchip same-family drop-in alternatives, and adds practical design notes that complement the manufacturer datasheet for the EUI-48/EUI-64 feature set.
24AA64T-E/MS - 64Kb I2C Serial EEPROM, 1.7V | Microchip
The Microchip Technology 24AA64T-E/MS is a 64 Kbit (8 K x 8) I2C-compatible serial EEPROM organized as a single block of 8K x 8-bit memory with a 2-wire serial interface, housed in an 8-pin MSOP package. Operating from 1.7V to 5.5V with a 400 kHz clock, it draws 1 uA standby current and 3 mA active current, supporting byte and page write modes with up to 32-byte page writes and a 5 ms write cycle time. A serial EEPROM is a type of non-volatile memory that retains stored data without power and is accessed through a low-pin-count serial protocol. In the broader memory hierarchy, EEPROMs sit between byte-alterable NV memory and one-time-programmable (OTP) ROM; the I2C subset specifically targets low-power, board-level configuration storage where two wires (SCL/SDA) are preferred over parallel busses. The 24AA64T-E/MS implements the industry-standard I2C protocol with hardware-selectable slave addresses via A0/A1/A2 pins, enabling up to eight devices on a single bus for 512 Kbit of shared storage. Key features include 1.7V minimum operating voltage for single-cell Li-ion or coin-cell systems, hardware write protection via the WP pin, 1 million erase/write cycle endurance, and >200-year data retention. The device supports both byte write and 32-byte page write operations, with a built-in 5 ms write-cycle timer that eliminates external polling. A separate data sheet documents Schmitt-triggered SCL/SDA inputs for noise-tolerant bus operation. Internally, the 24AA64T-E/MS uses a thin-oxide CMOS cell array with a charge-pump-driven high-voltage generator for byte-level programming. The I2C engine implements standard-mode (100 kHz) and fast-mode (400 kHz) timing with input filtering on both bus lines, mitigating the effects of ringing on long PCB traces or shared buses. Typical applications include consumer-electronics configuration storage (TV backlight and audio settings), medical-device parameter retention, industrial sensor calibration tables, and smart-card / RFID parameter storage. Its 1.7V minimum supply makes it ideal for battery-powered designs where EEPROMs historically required 2.5V or higher. Designers should use external pull-up resistors (typically 4.7 kohm for 400 kHz) on SCL/SDA, observe the 5 ms write-cycle time, and respect page-boundary alignment for multi-byte writes. The WP pin must be tied low or controlled by the host MCU to allow writes; tying it high hard-protects the entire array. This page synthesizes distributor pricing, drop-in alternatives, application guidance, and design notes that go beyond the manufacturer datasheet alone, giving engineers a one-stop resource for selecting and applying the 24AA64T-E/MS.
24CW640T-I/CS1668 - 64Kbit I2C EEPROM, 1MHz, 4-CSP | Microchip
The Microchip Technology 24CW640T-I/CS1668 is a 64-Kbit (8 Kbyte) I2C serial EEPROM organized as 8192 x 8 bits, housed in a 4-ball CSP (4-XFBGA, CSPBGA) wafer-level chip-scale package and rated for the industrial temperature range of -40C to +85C. It supports a 1 MHz I2C clock (compatible with Standard, Fast, and Fast-Plus modes) and provides 450 ns typical access time, with supply voltages from 1.8 V to 5.5 V, making it directly compatible with 1.8 V, 2.5 V, 3.3 V, and 5 V logic rails. A serial EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory IC that communicates over a simple two-wire bus. In the broader memory hierarchy, it sits between battery-backed SRAM and Flash, offering byte-level endurance (typically 1 million write cycles per page) and >200-year data retention at far lower pin count and cost than Flash. EEPROMs are commonly used to store configuration data, calibration coefficients, user preferences, and event logs that must survive power loss without the wear concerns of Flash. Key features of the 24CW640 include a built-in power-on reset (POR), software write protection (via the SWP pin / block-protection bits), hardware write-protect (WP) input, noise-suppression input filter on SDA/SCL, page-write buffering (up to 64 bytes), and a Schmitt-triggered SCL input for slow edges. The 4-CSP (0.86 mm x 0.86 mm typical) form factor is one of the smallest footprints available for serial EEPROM and is intended for space-constrained designs such as wearables, hearables, and miniature sensor modules. Architecturally, the device uses a CMOS floating-gate cell array with an integrated charge pump to support single-supply operation down to 1.8 V. The internal oscillator and timing state machine handle write-cycle management automatically, signaling completion via the I2C acknowledge polling mechanism, so the host MCU never needs to insert a fixed write delay beyond the page-write polling loop. Typical applications include IoT sensor node configuration storage, BLE/Zigbee module parameter retention, consumer device user settings (e.g., white-balance or RF calibration), medical wearable identification, smart-card / NFC-tag pairing data, and industrial module serial-number programming. The wide VCC range and industrial temperature grade also make it suitable for automotive sub-systems and outdoor equipment where extended ambient conditions are routine. When laying out the PCB, place the four CSP balls on a 4-ball land pattern with NSMD pads and route SDA/SCL as impedance-controlled lines with pull-ups to VCC. Note that WLCSP is sensitive to moisture (MSL-1); follow JEDEC J-STD-033 floor-life rules during assembly. This page synthesizes distributor pricing, drop-in 4-CSP alternatives from Microchip's 24CW family, application notes, and design considerations not aggregated on any single manufacturer or distributor page.
24CW640T-I/OT - 64Kbit I2C EEPROM, SOT-23-5 | Microchip
The Microchip Technology 24CW640T-I/OT is a 64-Kbit (8,192 x 8) I2C-compatible serial EEPROM with software write protection, supplied in a 5-pin SOT-23 surface-mount package and rated for the industrial -40C to +85C temperature range. It operates from a wide 1.6 V to 5.5 V supply and supports the standard, fast, and fast-plus I2C modes with clock rates up to 1 MHz, delivering 450 ns typical access time for byte read operations. The device provides byte- and page-level write capability (16-byte page) with hardware write-protect pin and software-controlled block protection, and it guarantees 1 million erase/write cycles per byte and 200-year data retention. A serial EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory that retains data without power and allows individual byte-level electrical reprogramming through a simple two-wire serial interface. Within the semiconductor memory hierarchy, EEPROM sits between one-time-programmable ROM and higher-density Flash, offering superior endurance and per-byte write granularity at the cost of lower density. The 24CW Series is positioned by Microchip as a low-power, low-cost, I2C-compatible EEPROM family optimized for consumer and industrial parameter storage. Key differentiating features of the 24CW640 include 64-Kbit density in the industry-standard 64-Kbit I2C EEPROM footprint, software-configurable write protection for upper half or full array, a dedicated WP pin for hardware protection, and Schmitt-triggered inputs for noise-tolerant bus operation. The wide 1.6 V to 5.5 V operating range allows direct connection to 1.8 V, 2.5 V, 3.3 V, or 5 V microcontroller I/O rails without level translation. Internally, the 24CW640 uses a CMOS floating-gate process with on-chip charge pump for byte-level programming and an integrated RC oscillator for write-cycle timing. The device supports standard, fast, and fast-plus I2C speeds (100 kHz, 400 kHz, and 1 MHz respectively), and its 450 ns access time provides fast read throughput for polling-based firmware designs. Page writes of up to 16 bytes maximize bus efficiency for parameter-table updates. Typical applications include consumer-electronics configuration storage, industrial sensor calibration data retention, IoT edge-node parameter logging, audio/video equipment user settings, and any battery-backed or power-cycled system that requires reliable non-volatile storage of small data sets. The SOT-23-5 package makes it well suited for space-constrained PCB designs. When designing with this part, place a 100 nF decoupling capacitor close to the VCC pin and observe I2C bus pull-up sizing (typically 2.2 k to 10 k depending on speed and bus capacitance). The WP pin must be tied to VCC or GND; leaving it floating can cause unreliable write-protect behavior. For page-write operations, ensure firmware respects the 16-byte page boundary to avoid wrap-around writes. This page synthesizes distributor pricing, drop-in I2C EEPROM alternatives, and practical design notes not aggregated on any single manufacturer or distributor page.
24FC1025-I/SN - 1Mbit I2C EEPROM 1.8-5.5V 1MHz 8-SOIC | Microchip
The Microchip Technology 24FC1025-I/SN is a 1024-Kbit (128K x 8) I2C-compatible Serial EEPROM with 1 MHz clock compatibility, organized as two blocks of 64K x 8 with selectable block addressing, and housed in an 8-pin SOIC (SN) package. It operates across a broad voltage range of 1.8V to 5.5V with a maximum clock frequency of 1 MHz and 400 ns access time, and supports page writes up to 128 bytes. An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory that retains data without power and allows byte-level erase and rewrite. The 24FC1025 belongs to the I2C serial EEPROM hierarchy, where each byte is addressed over a two-wire bus; the device supports standard (100 kHz), fast (400 kHz), and high-speed (1 MHz, "FC" = Fast Compatibility) modes. Functional address lines (A0, A1, A2) allow up to four devices on the same bus, yielding a maximum addressable capacity of 4 Mbits. Key features include 5 µA typical standby current, 5 mA active read/write current, hardware write-protect pin, built-in noise suppression filters on SCL/SDA, and a write cycle endurance of 1 million cycles per byte with >200-year data retention. The 24FC1025 has a hardware WP pin that protects the upper quadrant of the memory array when tied high, plus a sequential read mode that allows reading of the entire memory in a single operation. The architecture uses a two-wire serial interface with a 17-bit address space (block-select bit + 16-bit byte address) and an on-chip charge pump for the high-voltage programming circuits. The "FC" variant is the high-speed (1 MHz) version of the 24XX1025 family, while the 24LC1025 supports up to 400 kHz and the 24AA1025 supports up to 400 kHz with a lower 1.7V minimum supply. Typical applications include personal communications and data-acquisition parameter storage, industrial controllers needing event-log retention, consumer-electronics user-preference storage (TV/AVR/set-top box settings), and black-box flight-data recorder buffers. The wide operating voltage and small footprint also suit battery-powered IoT nodes that need persistent configuration storage. When designing with this part, observe the bus pull-up sizing rule: total capacitive bus loading (including trace capacitance and other devices) must remain below 400 pF for reliable 1 MHz operation. Decouple VCC with a 100 nF ceramic capacitor placed within 5 mm of the supply pin to suppress switching noise that can corrupt write operations. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone, drawing on the 20001941 revision of the Microchip 24AA1025/24LC1025/24FC1025 datasheet.
24LC1025-I/SM - 1Mb I2C Serial EEPROM | Microchip Technology
The Microchip Technology 24LC1025-I/SM is a 1024 Kbit (128 K x 8) I2C-compatible Serial Electrically Erasable PROM (EEPROM) housed in an 8-pin SOIJ (SM) package, designed for advanced low-power applications requiring reliable non-volatile data storage across an industrial voltage range of 2.5 V to 5.5 V. The part provides 1 Mbit of byte-addressable memory organized as 128 K x 8, with industry-standard 400 kHz I2C clocking, 900 ns access time, hardware write protection via the WP pin, and up to 128-byte page-write capability for efficient bulk programming. A Serial EEPROM is a type of non-volatile memory (NVM) that retains stored data without continuous power and communicates serially over a low-pin-count bus. In the broader memory hierarchy, EEPROMs sit between flash and SRAM - slower than flash but offering byte-level erase and write granularity without needing block buffers. The I2C interface used by the 24LC1025 reduces wiring to just two signal lines (SDA, SCL), allowing up to four devices on a bus (two 24LC1025 address bits plus two fixed high-order bits) while saving board space compared to parallel EEPROM or NOR flash alternatives. Key features include a maximum read/write supply current of 3 mA active and 1 uA standby typical, more than 1 million erase/write cycles endurance per page, and greater than 200 years of data retention. The cascadable architecture allows two 24LC1025 devices to be addressed on the same bus, providing a simple upgrade path to 2 Mbit non-volatile storage. The SOIJ-8 (SM) package has an industrial temperature rating of -40 C to +85 C, making it suitable for harsh-environment deployment. The internal architecture uses a CMOS floating-gate cell array with on-chip charge pump generation, providing byte and page write modes with automatic erase-before-write and ACK polling capability. The device supports both standard (100 kHz) and fast (400 kHz) I2C modes, with input filtering on both SDA and SCL to suppress bus noise and ensuring robust communication in electrically noisy environments such as motor control or industrial PLC systems. Typical applications include data logging in personal communications and metering equipment, industrial controllers requiring parameter storage, black-box event recorders in automotive aftermarket accessories, and I2C-based configuration storage on microcontroller co-processor boards. The cascadable addressing scheme also makes it a good fit for audio/video equipment storing user preferences and calibration tables. When designing with the 24LC1025-I/SM, allow adequate VCC decoupling (a 0.1 uF ceramic capacitor close to the power pin) and observe the write-cycle timing of 5 ms maximum per page. Hardware write-protect (WP tied to VCC) prevents accidental writes during power transitions, which is critical for mission-critical parameter storage. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet alone.
24LC1025T-I/SM - 1Mb I2C EEPROM, 2.5-5.5V, 8-SOIJ | Microchip
The Microchip Technology 24LC1025T-I/SM is a 1 Mbit (128K x 8) serial I2C EEPROM in an 8-SOIJ package, capable of operation across a broad voltage range of 2.5V to 5.5V with a 400 kHz I2C clock and a 900 ns access time, supplied on Tape & Reel for high-volume surface-mount assembly. What is an I2C Serial EEPROM? An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory that retains data without power and supports byte-level electrical erase and rewrite. I2C (Inter-Integrated Circuit) serial EEPROMs communicate over a two-wire bus (SCL clock + SDA data), making them ideal when a system microcontroller needs a small, low-pin-count, low-power store for configuration, calibration, or event logs. In the component taxonomy, the 24LC1025T-I/SM sits at: serial EEPROM -> EEPROM -> non-volatile memory -> memory IC -> semiconductor IC. Compared with Flash, EEPROM offers byte-level write granularity, simpler firmware drivers, and far higher endurance-per-byte for small-parameter storage. Key features of the 24LC1025T-I/SM include a 1 Mbit (128K x 8) density organized across two 64K-byte address blocks with software-selectable block addressing via the A0/A1/A2 device-address pins (function address lines), hardware write-protect (WP), and support for both random and sequential read across the full 0000h to 1FFFFh address range. The device implements a 128-byte page-write buffer, cascading write capability up to 64 bytes per page, and self-timed erase/write cycles. Typical active read current is 1 mA maximum, standby current is 1 µA maximum, and the device operates across the industrial -40C to +85C temperature range. Technically, the 24LC1025T-I/SM uses Microchip's proprietary CMOS EEPROM process and an I2C-compatible two-wire serial interface (SMBus-compatible at lower speeds). The 7-bit slave address uses the upper-four fixed bits (1010) with three user-configurable device-address bits, allowing up to eight 24LC1025 devices to share a single I2C bus for total storage up to 8 Mbit. Write operations require only the slave address, word address, and up to 128 bytes of data; the device automatically generates the ACK and ACK-after-write polling response. Typical applications include data logging in personal communications devices, parameter storage in industrial data-acquisition systems, configuration retention for consumer electronics, black-box event recording in metering equipment, and storing calibration constants in sensor modules. The 8-SOIJ (SOIJ-8) J-lead surface-mount package provides stronger lead compliance and better thermal-cycle reliability than standard SOIC, making the part well-suited to automotive under-hood, industrial, and high-vibration environments. When designing with this device, note that the WP pin must be tied to VCC or GND (it must not float), and that a 100 nS minimum SCL high/low time and 1.2 µS bus free time must be respected. Pull-up resistors on SDA and SCL are required; typical values are 4.7 kohm for 3.3V/5V VCC and shorter buses, and 2.2 kohm for longer or more heavily loaded buses. This page synthesizes distributor pricing, drop-in same-package alternatives, design notes, and application guidance not consolidated on the Microchip product page or any single distributor listing.
24LC32A-E/SN - 32Kb I2C EEPROM, 8-SOIC | Microchip Technology
The Microchip Technology 24LC32A-E/SN is a 32-Kbit (4K x 8) I2C-compatible serial EEPROM organized as a single block of byte-wide memory with a standard 2-wire serial interface. Housed in an 8-pin SOIC (SN) package with an industrial-grade -40C to +125C temperature range and a 2.5V to 5.5V supply range, it supports up to 400 kHz I2C bus frequency with 900 ns access time and offers 1 uA standby current and 1 mA active current. The 'E' suffix denotes the extended industrial temperature grade while '/SN' denotes the 8-pin SOIC narrow-body package. A serial EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory device that retains data without a battery. The 24LC32A-E/SN belongs to the EEPROM memory IC family, which sits within non-volatile memory and ultimately under semiconductor devices. EEPROMs use the I2C (Inter-Integrated Circuit) 2-wire bus for communication, requiring only SDA (data) and SCL (clock) lines, plus power and ground. This serial-interface approach drastically reduces pin count versus parallel EEPROMs, enabling small packages and PCB-friendly routing. Key features include hardware write protection via the WP pin, software write-protect for the upper 1/4 of memory array, page-write buffering up to 32 bytes per page, and over 1 million erase/write cycles per page with greater than 200-year data retention. The 24LC32A-E/SN supports both Standard-Mode (100 kHz) and Fast-Mode (400 kHz) I2C operation, with seven user-selectable slave addresses via the A0, A1, A2 pins, enabling up to eight 24LC32A devices on a single I2C bus. The device uses CMOS technology and is built around an on-chip charge pump that generates the high voltage needed for byte-level programming. It also features noise suppression filters on the SDA and SCL inputs, schmitt-trigger inputs for bus-noise immunity, and a Power-on Reset (POR) circuit that initializes the device to a known state. Internal ESD protection exceeds 4 kV HBM. Typical applications include consumer electronics parameter storage (TV settings, white-goods calibration), industrial automation configuration data, automotive infotainment and accessory modules, smart metering calibration and tamper logs, medical device settings storage, IoT endpoint device credentials and logging, and any embedded microcontroller design requiring small non-volatile storage with low standby current. When designing with this device, place a 10 kohm pull-up on both SDA and SCL and add a 100 nF decoupling capacitor near the VCC pin. The WP pin may be tied low to enable writes or high to lock the array - never leave it floating. For multi-byte writes, respect the 32-byte page boundary to avoid unintended wrap-around. This page synthesizes distributor stock and pricing, drop-in replacement alternatives, and practical I2C bus design notes not consolidated in the Microchip datasheet alone.
24LC512-I/ST - 512Kb I2C EEPROM 8-TSSOP | Microchip
The Microchip Technology 24LC512-I/ST is a 512 Kbit (64K x 8) I2C-compatible Serial EEPROM in an 8-pin TSSOP package, designed for low-power non-volatile data storage across industrial-grade temperature ranges. The device operates from 2.5V to 5.5V, supports a maximum clock frequency of 400 kHz, and offers byte-level access within 900 ns, making it well suited to high-throughput data-logging designs. A Serial EEPROM is a type of non-volatile memory that retains data without a battery and is accessed through a simple two-wire serial protocol. The 24LC512 belongs to the broader EEPROM family, which sits alongside flash and FRAM in the non-volatile memory hierarchy. It is intended for systems that need frequent byte-level rewrites with endurance far higher than flash, typically 1 million erase/write cycles per page and over 200 years of data retention. Key features of the 24LC512-I/ST include a 128-byte page write buffer, hardware write-protect pin (WP), cascadability for up to eight devices on a single I2C bus via the A0/A1/A2 address pins, and typical standby current of only 1 uA with active read current of approximately 1 mA at 5.5V. The internal organization is 512 pages of 128 bytes each, accessed by a 16-bit address pointer transmitted by the master. The device uses Microchip's proprietary CMOS EEPROM process with a self-timed erase/write cycle, freeing the host MCU to perform other tasks while a write completes. Built-in error-correction and hardware data protection guard against partial writes during power-down, which is important for industrial and consumer systems that may lose power mid-write. Typical applications include industrial data loggers, automotive accessory modules, consumer-electronics parameter storage, black-box and metering recorders, embedded system configuration EEPROM, and I/O expansion when paired with an MCU that has limited internal non-volatile memory. The wide VCC range and industrial -40C to +85C operating temperature make it a versatile drop-in for factory, automotive and battery-powered systems. When designing with the 24LC512-I/ST, ensure the I2C pull-up resistors are sized for the bus capacitance and the target clock rate (typically 2.2-10 kohm at 400 kHz). Place a 0.1 uF decoupling capacitor close to VCC, and observe the mandatory 5 ms write-cycle time between successive page writes to avoid status-poll overhead. This page synthesizes distributor pricing, drop-in alternatives, and practical I2C EEPROM design notes that are not consolidated in any single manufacturer datasheet, giving you a one-stop engineering reference.
24LC512T-I/SM - 512Kbit I2C EEPROM, 400kHz, 8-SOIJ | Microchip
The Microchip Technology 24LC512T-I/SM is a 512-Kbit (64K x 8) I2C serial EEPROM organized as 65,536 bytes of 8-bit wide non-volatile storage, housed in an 8-pin SOIJ (Small Outline J-lead) surface-mount package. According to the manufacturer datasheet (Microchip document 21754M), the device operates across a wide supply voltage range of 2.5V to 5.5V and supports a maximum I2C clock frequency of 400 kHz in the LC variant, with a typical access time of 900 ns. The "T" suffix indicates Tape and Reel packaging, while the "I" denotes the industrial operating temperature range of -40C to +85C. A serial EEPROM is a type of non-volatile memory that retains data without power using an electrically erasable programmable read-only memory (EEPROM) cell array, and is accessed over a low-pin-count serial bus such as I2C. Within the broader memory hierarchy, serial EEPROMs sit alongside Flash memory, SRAM, and DRAM as byte-level non-volatile storage optimized for low-power, small-footprint, frequent-write applications such as configuration storage, calibration constants, and user preference retention in battery-backed or energy-harvesting systems. Key features of the 24LC512T-I/SM include hardware write protection via the WP pin, a 128-byte page write buffer for efficient bulk programming, 64-byte page write modes, hardware and software write protection, and support for up to eight devices on a single I2C bus via three address pins (A0, A1, A2). Endurance is rated at greater than 1,000,000 erase/write cycles per page with data retention exceeding 200 years, making it suitable for applications requiring long-term parameter storage with periodic in-system updates. Architecturally, the device uses a CMOS process with on-chip charge pump for high-voltage generation during programming. An internal data buffer holds the most recent read address, and a self-timed programming cycle offloads the host controller during writes. A cascading feature allows up to eight 24LC512 devices to share a single I2C bus, expanding the effective storage to 4 Mbit without additional addressing logic. Typical applications include personal communications devices, data acquisition systems, industrial controllers, automotive infotainment and body modules, smart metering, white goods, and any embedded system requiring reliable configuration storage. The wide voltage range (2.5V-5.5V) and low standby current (typically 1 uA) make it especially attractive for battery-powered IoT nodes and portable instruments where every microamp matters. When designing with the 24LC512T-I/SM, place 0.1 uF decoupling capacitors close to VCC, use proper I2C pull-up resistors (typically 4.7 kohm at 400 kHz), and ensure write cycle time (5 ms max) is respected by the firmware. Always tie WP low for read/write operation or high to protect the upper 256 bytes of memory. Operating above 5.5V will permanently damage the device. This page synthesizes distributor pricing, drop-in same-package alternatives from the same 24LC512 family, and practical design notes not found in the manufacturer datasheet.
24LC512T-I/ST - 512Kbit I2C EEPROM, 400kHz | Microchip
The Microchip Technology 24LC512T-I/ST is a 512 Kbit (64K x 8) I2C-compatible Serial Electrically Erasable PROM (EEPROM) in an 8-pin TSSOP package, supplied on Tape & Reel. It supports a broad operating voltage range from 2.5V to 5.5V, an I2C clock frequency up to 400 kHz, and a 900 ns access time, making it a drop-in upgrade for legacy 24Cxx and 25xxx serial EEPROMs in mixed-voltage embedded designs. A Serial EEPROM is a type of non-volatile memory (NVM) that retains stored data when power is removed and communicates serially over a few wires, in contrast to parallel memory which requires many more I/O lines. Within the memory hierarchy, the 24LC512 sits in the EEPROM sub-family of Memory ICs -> Non-volatile memory -> Semiconductor memory. It is typically chosen for small, frequently-updated parameter storage rather than bulk data, with 1 million erase/write cycles per page and >200-year data retention. Key features include 128-byte page write buffer, hardware write-protect pin, cascadable up to 8 devices on a single I2C bus via the three address pins A0/A1/A2 (giving 8 unique 7-bit slave addresses), and an industry-standard 2-wire I2C interface compatible with most microcontrollers. The 'I' suffix denotes the industrial temperature grade of -40C to +85C, and the 'T' suffix denotes Tape & Reel packaging. The 24LC512 variant operates from 2.5V to 5.5V, the 24AA512 variant operates from 1.7V to 5.5V, and the 24FC512 variant runs to 1 MHz clock frequency. Typical applications include storage of user-configurable settings, calibration constants, and event logs in industrial controllers, automotive infotainment, medical instrumentation, smart meters, IoT edge nodes, and consumer appliances. The TSSOP-8 footprint is pin-compatible with the 24C256 and most 24Cxx/24LCxx families, simplifying PCB migration from 32 Kbit or 64 Kbit legacy parts to 512 Kbit without layout changes. When designing with this device, observe the I2C pull-up resistor selection (typically 2.2 kohm to 10 kohm depending on bus capacitance and clock speed), enable proper write-cycle timing (5 ms max page write), and connect the WP pin high to protect the upper 256 Kbit quadrant during mission-critical operation. Avoid cascaded bus topologies exceeding 400 pF total capacitance when running at 400 kHz.
24LC64T-I/SN - 64Kbit I2C EEPROM, 400kHz, SOIC-8 | Microchip
The Microchip Technology 24LC64T-I/SN is a 64-Kbit (8K x 8) I2C-compatible serial EEPROM organized as a single block of 8 Kbytes with a 2-wire serial interface. The "T" suffix indicates tape-and-reel packaging; the "I" grade denotes industrial temperature range (-40C to +85C); the "/SN" suffix marks the 8-pin SOIC package. It supports standard (100 kHz) and fast (400 kHz) I2C modes with access time up to 900 ns. A serial EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory that communicates over a simple 2-wire bus and retains data without power. In the system hierarchy it sits under non-volatile memory -> memory IC -> integrated circuit. Serial EEPROMs are valued for low pin count, low standby current, byte-level write granularity, and high endurance, making them well-suited for storing configuration, calibration, and user-data records that must survive power cycles. Key features include 64 Kbit (8 KB) density in 8-bit width, single 2.5V to 5.5V supply operation, 1 uA typical standby current and 3 mA active current, hardware write-protect pin, 32-byte page write mode, more than 1 million erase/write cycles per page, and data retention greater than 200 years. The device also offers cascadable up to 8 devices on a single I2C bus via three address pins, allowing expansion up to 512 Kbit per bus segment. The 24LC64 uses a CMOS process with on-chip charge pump for byte and page programming; the high-voltage generator produces the elevated programming voltage internally so no external VPP supply is needed. Schmitt-triggered SCL/SDA inputs improve noise immunity in industrial environments, while the dedicated WP pin lets designers freeze the upper 32 Kbit of array against accidental writes. Typical applications include consumer-electronics configuration storage, industrial sensor calibration logs, smart-card parameter retention, automotive infotainment settings, and any battery-backed or energy-harvesting system requiring low standby current. When designing with the 24LC64T-I/SN, observe the 2.5V minimum VCC for proper read/write and ensure pull-up resistors on SDA/SCL are sized for the total bus capacitance; 2.2 kohm to 10 kohm is typical for 400 kHz operation with multiple devices. This page consolidates distributor pricing, drop-in same-brand and cross-brand alternatives, and practical design notes not found in the manufacturer datasheet alone.
25AA1024T-I/SM - 1Mbit SPI EEPROM 1.8V SOIJ-8 | Microchip
The Microchip Technology 25AA1024T-I/SM is a 1 Mbit serial EEPROM with an industry-standard SPI-compatible serial bus, organized as a single block of 128K x 8-bit (131,072 bytes). It operates from a wide 1.8 V to 5.5 V supply, supports SPI clock rates up to 20 MHz, and is housed in an 8-pin SOIJ package. The "T" suffix denotes Tape & Reel packaging and the "I" denotes the industrial -40C to +85C temperature range. A serial EEPROM is a type of non-volatile memory that retains stored data without power and communicates serially over a few wires rather than a parallel bus. EEPROMs occupy the memory hierarchy tier between battery-backed SRAM and Flash: they offer byte-level write granularity (unlike Flash which typically requires page/sector erases), unlimited read cycles, and write endurance of up to 1 million cycles per byte. They are commonly used as parameter, configuration, calibration, and event-log storage in embedded systems. Key features of the 25AA1024T-I/SM include a 256-byte page write buffer for efficient sequential writes, hardware write-protect (WP), hold pin for pausing serial communication mid-transaction, software write-protection for the upper quarter of memory, and built-in power-on reset (POR) plus write enable latch (WEL). It also supports page, sector (64 KB) and chip erase commands borrowed from Flash for fast bulk clearing, although these are not required for normal byte/page writes. Internally, the device uses a CMOS EEPROM array with a charge-pump write circuit and an SPI mode 0 and mode 3 compatible interface. Page write time is up to 5 ms with full status polling via the WIP/WEL bits in the STATUS register. Compared to MRAM or FRAM, the 25AA1024 trades write speed for the lowest cost-per-bit and widest ecosystem support in non-volatile storage. Typical applications include storing user preferences and calibration constants in consumer electronics, asset tracking records in industrial nodes, firmware revision tags in medical devices, and data logging in automotive subsystems. It is well suited to systems that need reliable, low-power, byte-writeable non-volatile storage accessible from a microcontroller via SPI. When designing with this part, place a 100 nF decoupling capacitor close to VCC, keep SPI traces short, and tie CS, WP and HOLD high through a pull-up resistor when unused to prevent unintended writes. Note that byte writes take up to 5 ms - factor this into your real-time write budget. This page synthesizes verified distributor pricing, drop-in alternatives, and practical design notes for the 25AA1024T-I/SM beyond what is shown in the manufacturer datasheet.
25LC1024-I/SM - 1Mb SPI Serial EEPROM 8-SOIJ | Microchip
The Microchip Technology 25LC1024-I/SM is a 1 Mbit (128K x 8) Serial EEPROM with SPI bus interface, operating from 2.5V to 5.5V, housed in an 8-pin SOIJ (208 mil) package. The device supports a maximum SPI clock rate of 20 MHz and is organized as one contiguous 128K-byte block with byte-level and page-level write operations and 256-byte page size. A serial EEPROM is a non-volatile memory device that stores data byte-by-byte over a low-pin-count serial interface rather than a parallel bus. Within the broader semiconductor taxonomy, EEPROM belongs to non-volatile memory (NVM), which also includes Flash, FRAM, and MRAM. SPI EEPROMs occupy a stable position above SRAM/DRAM in the volatile-vs-non-volatile hierarchy and remain widely used for low-density parameter storage where byte-level write granularity, long data retention (200 years typical), and ultra-low standby current are required. Key features of the 25LC1024-I/SM include software and hardware write protection via the WP pin, a HOLD pin that allows pausing a serial communication without deselecting the device, and the ability to perform chip, sector (64KB), and page erase operations in addition to standard byte and page writes. The 8-SOIJ (Small Outline Isolated J-lead) package offers robust lead-frame compliance for hand-solder and industrial assembly. The 25LC1024 uses the industry-standard SPI protocol with mode 0 and mode 3 compatibility, four standard instructions (READ, WRITE, WREN, WRDI) plus additional status-register and erase commands. The internal charge pump generates the high voltage required for byte-write operations without external HV supplies. A 32-byte SRAM write buffer and built-in write-status indication simplify firmware development. Typical applications include industrial control parameter storage, automotive subsystem configuration, consumer-electronics user preferences, medical device calibration data, black-box/event data recorders, and any MCU-based system that needs reliable byte-modifiable non-volatile storage on a minimal pin budget. When designing with this device, ensure that CS transitions during HOLD remain within the datasheet-specified setup and hold times, and that the WP pin is properly tied (high to protect the upper quadrant or low to allow full writes) according to system security requirements. This page synthesizes distributor pricing, verified drop-in alternatives in the same 8-SOIJ footprint, and practical design notes not found in the manufacturer datasheet alone, providing a self-contained engineering reference.
25LC512-E/SN - 512Kbit SPI EEPROM, 20MHz, 2.5-5.5V | Microchip
The Microchip Technology 25LC512-E/SN is a 512 Kbit (64K x 8) Serial EEPROM organized as a single block of 64K bytes and accessed through a standard Serial Peripheral Interface (SPI) compatible bus. It supports clock rates up to 20 MHz and operates across a wide 2.5V to 5.5V supply range in an 8-pin SOIC (SN) package. The -E suffix denotes the -40C to +125C industrial/extended operating temperature range, making the part suitable for harsh-environment designs. What is a Serial EEPROM? A serial EEPROM is a type of non-volatile memory (NVM) that retains data without power and communicates over a low-pin-count serial bus (SPI, I2C, or Microwire). Within the memory hierarchy, EEPROMs sit below Flash for write endurance (typically 1M cycles per byte/page) but offer byte-level granularity, eliminating the sector-erase overhead of Flash. The 25LC512 family belongs to the broader category of memory ICs, specifically byte-alterable non-volatile storage used for configuration, calibration, and event-log retention. Key features include page, sector, and chip erase functions typically found in Flash products - these are not required for normal byte/page writes. The device offers a 128-byte page write buffer, hardware and software write protection via the /WP and /HOLD pins, and a status register flag for write-cycle completion. Self-timed erase and write cycles complete in 5 ms maximum, and an additional 128-byte page mode allows efficient sequential writes. The 25LC512 uses a CMOS process with on-chip latching to support SPI Mode 0 (CPOL=0, CPHA=0) and Mode 3 (CPOL=1, CPHA=1), giving it compatibility with virtually any microcontroller SPI peripheral. Typical active read current is around 5 mA at 5V/20 MHz, with standby current under 1 uA, enabling low-power sleep-mode data retention designs. Typical applications include consumer-electronics configuration storage (TV backlight calibration, white-balance tables, MAC address backup), industrial sensor calibration constants, medical-device patient-log retention, and automotive accessory parameter storage. The wide voltage range also enables direct 3.3V MCU interfacing without level shifters. When designing with this device, keep /CS low during a full read or write sequence and respect the 5 ms write-cycle time before polling the status register. For high-reliability applications, plan for wear-leveling because each byte/page supports up to 1 million erase/write cycles. Use external pull-ups on /WP and /HOLD if those pins are tied high in the layout. This page synthesizes distributor pricing, drop-in alternative MPNs, and practical design notes not found in the standalone manufacturer datasheet.
25LC512-I/SN - 512Kb SPI EEPROM, 20MHz, 8-SOIC | Microchip
The Microchip Technology 25LC512-I/SN is a 512 Kbit (64 Kbyte) serial EEPROM organized as 64K × 8 bits, accessed via a standard Serial Peripheral Interface (SPI) compatible bus at up to 20 MHz, and housed in an 8-pin SOIC (SN) package. It operates from a single 2.5 V to 5.5 V supply and is qualified over the industrial -40 °C to +85 °C temperature range. The device delivers byte-level and page-level write operations (128-byte page), features hardware- and software-write protection, and offers 200-year data retention plus 1 million erase/write cycle endurance per page. An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory that retains data when power is removed and supports individual byte-level in-system rewrite without first erasing an entire block. EEPROMs sit between true ROM and Flash in the non-volatile memory hierarchy: unlike Flash, they do not require a sector erase before byte write, and unlike ROM, they are reprogrammable in-circuit. They are commonly used for device configuration, calibration constants, user preference storage, and small data-logging buffers where byte-level updates dominate the workload. The 25LC512 distinguishes itself with a 20 MHz maximum clock rate, low active current (~5 mA typical at 5 V, 20 MHz), and a deep power-down mode that drops standby current below ~1 µA. The SOIC-8 package, low pin count, and industry-standard SPI command set make it a straightforward drop-in for any system with a microcontroller or SBC that exposes an SPI master. Page, sector (4-Kbyte), and chip erase commands extend its feature set beyond plain EEPROM toward light Flash-style use. Typical applications include storing user settings, calibration coefficients, and black-box event logs in industrial controllers, home appliances, automotive accessory modules, medical instrumentation, and consumer electronics. The wide VCC range (2.5–5.5 V) lets the same part ride on 3.3 V or 5 V rails without level translation. Combined with the SPI bus, designers can chain multiple 25-series EEPROMs by giving each a unique CS line on the same shared SCK/SI/SO bus. When designing with this part, observe the page-write timing: a status register poll is required before the next write, since writes are non-blocking on the SPI command interface. Hold the CS pin low for the entire SPI transaction and respect tWC (max 5 ms page write cycle) before issuing the next command. Decouple VCC with a 0.1 µF ceramic capacitor placed within a few millimetres of the supply pin. This page synthesizes distributor pricing, verified drop-in alternatives, and practical design notes that are not consolidated in any single manufacturer datasheet, helping engineers select and qualify the 25LC512-I/SN quickly for new designs and existing BOMs.
25LC512T-E/SN - 512Kbit SPI EEPROM, 20 MHz, 8-SOIC | Microchip
The Microchip Technology 25LC512T-E/SN is a 512 Kbit (64K x 8) Serial EEPROM with SPI bus interface, 20 MHz maximum clock speed, and a 2.5 V to 5.5 V single supply voltage range, offered in a 150-mil 8-pin SOIC (SN) package on tape-and-reel. The "T" suffix designates Tape and Reel packaging, the "E" denotes the Extended (-40C to +125C) operating temperature range, and "/SN" specifies the SOIC-8 package variant. The device supports byte-level and page-level write operations with a 128-byte page size, plus optional Page, Sector, and Chip erase functions typically associated with Flash, while also featuring hardware write protection (WP), Hold function, and built-in write enable latch (WEL) for robust SPI bus operation. What is a Serial EEPROM? A Serial EEPROM is a type of non-volatile memory (NVM) that retains stored data when power is removed and communicates serially over a few wires (SPI, I2C, or Microwire) rather than with a wide parallel bus. In the memory hierarchy, EEPROMs sit below Flash for density but offer finer write granularity (single-byte writes), much higher write endurance (typically 1M cycles), and lower power consumption. The 25LC512 belongs to the SPI EEPROM sub-family, providing a middle ground between tiny I2C EEPROMs and larger parallel Flash, ideal for storing configuration parameters, calibration constants, and user preferences. Key features include 512 Kbit of user-accessible memory organized as 64K x 8, a 20 MHz maximum SPI clock supporting Mode 0 and Mode 3, a 5 ms maximum page write cycle time, hardware and software write protection, and a built-in power-on/power-down protection circuit. The wide 2.5 V to 5.5 V VCC range allows direct interfacing with 3.3 V and 5 V microcontrollers without level shifters, and the SOIC-8 footprint is JEDEC-standard, enabling drop-in compatibility with most competitor SPI EEPROMs. The 25LC512 uses a CMOS process with on-chip high-voltage generation for the floating-gate cells, eliminating the need for an external VPP supply. Its 128-byte page write buffer, automatic erase-before-write within the page, and STATUS register polling (via the WIP bit) simplify firmware drivers. Power-down protection circuitry prevents inadvertent writes during supply transitions, a critical feature for industrial systems with hot-plug or brown-out scenarios. Typical applications include consumer electronics for storing user preferences and language strings, industrial automation modules holding calibration data and serial numbers, medical devices logging patient/device identifiers, automotive accessory nodes (non-safety subsystems), networking equipment for MAC address and configuration backup, and IoT edge devices retaining sleep-state parameters through battery swaps. When designing with the 25LC512, place a 0.1 uF decoupling capacitor within 5 mm of the VCC pin and keep SPI traces short to avoid ringing on MISO/MOSI/SCK. For multi-master SPI buses, ensure the CS signal is properly managed; for write endurance concerns, implement wear-level wear-leveling by rotating writes across the page boundaries when storing frequently updated data such as event counters. This page synthesizes Microchip datasheet parameters, current distributor pricing, real-time stock state, drop-in alternative MPNs from same-brand and cross-brand vendors, and practical PCB/firmware design guidance not consolidated in a single vendor document.
27C256-120N - 32Kx8 120ns CMOS EPROM | ASI | Legacy Memory
The ASI 27C256-120N is a 256 Kbit CMOS UV-erasable EPROM organized as 32K words by 8 bits (32K bytes), with a 120 ns access time in a 28-pin DIP package (the N suffix denotes plastic DIP). It operates from a single +5 V power supply with a standard +/-10% tolerance and follows the JEDEC-approved 27C256 pinout. An EPROM (Erasable Programmable Read-Only Memory) is a non-volatile memory device that is programmed electrically and erased by exposure to ultraviolet light through a quartz window. EPROMs sit within the broader memory hierarchy of semiconductor memory: read-only memory -> non-volatile memory -> memory IC -> integrated circuit. They were the dominant firmware storage medium before Flash memory displaced them. Key features include a 120 ns address-to-output access time suitable for mid-speed microprocessor bus cycles, low 20 uA typical CMOS standby current for power-sensitive designs, single +5 V read operation, and 100% Flashrite programming for fast programming cycles. The device uses CMOS split-gate EPROM cell technology, providing low static power consumption and fast access across the full operating range. Data retention and programming parameters (VPP level, program pulse width) are defined in the manufacturer datasheet. Typical applications include legacy embedded firmware storage for 8-bit and 16-bit microcontrollers, BIOS/firmware cartridges in retro computing and arcade equipment, industrial control boards in long-lifecycle equipment, and telecommunications line cards. Design consideration: the 27C256 family is end-of-life; for new designs use a pin-compatible Flash or EEPROM such as the AT29C256, noting that pin 26 / pin 27 functions differ on EEPROM derivatives and in-circuit reprogramming behavior changes. This page synthesizes distributor stock references, cross-manufacturer drop-in equivalents, and practical design notes not found in the manufacturer datasheet.