M24256-BWMN6TP - 256Kbit I2C EEPROM, 1MHz, 8-SOIC | STMicroelectronics
MPN: M24256-BWMN6TP ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.62 | $0.62 |
| 10 | $0.55 | $5.50 |
| 100 | $0.41 | $41.00 |
| 500 | $0.36 | $180.00 |
| 1,000 | $0.32 | $320.00 |
M24256-BWMN6TP Overview
An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a type of non-volatile memory that retains stored data when power is removed and supports byte-level in-system writes via an electrical signal. EEPROMs sit beneath Flash in the memory hierarchy: they offer lower density but higher endurance per cell (typically 1 million write cycles for this family) and byte-level granularity, making them well suited for storing user-configurable parameters, calibration constants, device IDs, and event logs that change frequently during the lifetime of a product.
The M24256-BWMN6TP integrates advanced write-protection features: a Write Protect (WP) pin that hard-locks the upper quadrant of the array, and three hardware address pins that allow bus-address configuration on the fly. The device supports both byte-write and page-write (up to 64-byte page) modes, with a built-in write-cycle completion polling mechanism that simplifies firmware. The SO-8 package is a JEDEC-standard surface-mount form factor widely accepted for industrial designs.
Architecturally, the device is built on STMicroelectronics' proprietary CMOS EEPROM process, which delivers >4 million write cycles per byte and >200-year data retention. The on-chip charge pump generates the high-voltage programming pulses required to tunnel electrons through the floating gate, all managed by an internal state machine that frees the host microcontroller from page-buffer timing.
Typical applications include industrial control parameter storage, consumer-set user preferences, smart-meter calibration data, automotive accessory identification, medical device log retention, and I²C port expansion on small microcontrollers that lack internal non-volatile storage. Designers choose this part when they need reliable, byte-writeable memory in a familiar 8-pin footprint.
When designing with the M24256-BWMN6TP, place 0.1 µF decoupling close to VCC and respect the bus idle time (tBUF) of 0.5 µs minimum to ensure proper start-condition detection. Hardware address pins E0/E1/E2 must be tied to VCC or GND (no floating inputs allowed).
This page synthesizes distributor pricing, same-family drop-in alternatives, and practical design notes for the M24256-BWMN6TP not found in the manufacturer datasheet alone.
Drop-in alternatives for M24256-BWMN6TP — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
M24256-BWMN6TP/A
✅ Drop-In📋 Reference alternative (not in catalog)
M24256-BWMN6TP/K
✅ Drop-In📋 Reference alternative (not in catalog)
M24256-BRMN6TP
✅ Drop-In📋 Reference alternative (not in catalog)
AT24C256C-SSHL-T
✅ Drop-In📋 Reference alternative (not in catalog)
BR24G256F-3
✅ Drop-In📋 Reference alternative (not in catalog)
24LC256-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
M24256-BWMN6TP Maximum Ratings & Electrical Characteristics
| Memory Type | EEPROM (Electrically Erasable Programmable ROM) |
| Memory Size | 256 Kbit (32 Kbyte) |
| Memory Organization | 32 K × 8 bits |
| Interface | I²C (2-wire serial) |
| Maximum Clock Frequency | 1 MHz |
| Access Time | 450 ns |
| Supply Voltage (VCC) | 2.5 V to 5.5 V |
| Operating Temperature Range | -40 °C to +85 °C |
| Write Cycle Time (typ.) | 5 ms (byte/page) |
| Write Endurance | 1 M cycles per byte (typical) |
| Data Retention | >40 years |
| Package | SOIC-8 (SO-8, 150-mil) |
| Mounting Type | Surface Mount |
| Chip Enable Pins | 3 (E0, E1, E2) - supports up to 8 devices on one bus |
| Write Protect Pin | Yes (WP, hardware-locks upper quadrant) |
| Page Size | 64 bytes |
| MSL Level | 1 (unlimited floor life) |
| RoHS Status | Compliant |
M24256-BWMN6TP Pin Configuration
| Pin 1 | E0 — Chip Enable input 0 (hardware address bit 0) |
| Pin 2 | E1 — Chip Enable input 1 (hardware address bit 1) |
| Pin 3 | E2 — Chip Enable input 2 (hardware address bit 2) |
| Pin 4 | VSS — Ground |
| Pin 5 | SDA — Serial Data (I²C bidirectional data line) |
| Pin 6 | SCL — Serial Clock (I²C clock input) |
| Pin 7 | WP — Write Protect (active-high; locks upper quadrant when high) |
| Pin 8 | VCC — Supply voltage (2.5 V to 5.5 V) |
Typical Applications
M24256-BWMN6TP is suitable for 6 applications: Industrial Control Parameter Storage, Smart Meter Calibration and Logging, Consumer Electronics User Preference Storage, IoT Sensor Hub Configuration Memory, Medical Device Event Log Retention, Automotive Accessory Identification.
Industrial Control Parameter Storage
The M24256-BWMN6TP fits industrial control parameter storage because its 256-Kbit (32 Kbyte) capacity comfortably holds hundreds of 16-bit calibration coefficients, PID tuning constants, and machine setup parameters. Its 1 M write-cycle endurance and >40-year data retention exceed the lifetime of most factory-floor installations, while the 2.5 V-5.5 V supply range interfaces directly with 3.3 V and 5 V MCUs. The hardware WP pin enables tamper-resistant configuration locking in the field, and the three Chip Enable pins let a single I²C bus carry configuration memory for multiple subsystems, reducing wiring complexity in PLC and HMI designs.
Recommended
Smart Meter Calibration and Logging
Smart electricity, water, and gas meters use the M24256-BWMN6TP for storing calibration coefficients, tariff schedules, and rolling consumption logs. The 256-Kbit capacity is sufficient for several months of hourly metering data alongside calibration tables, and the 1 MHz I²C bus allows the meter MCU to retrieve stored values at boot without delay. The 1 M write-cycle endurance handles daily logging writes over a 10+ year deployment lifetime. Three hardware address pins (E0/E1/E2) allow multiple EEPROMs on the same bus for segmented storage of energy, water, and gas channels in multi-utility meters.
Recommended
Consumer Electronics User Preference Storage
The M24256-BWMN6TP is widely used in TVs, set-top boxes, audio equipment, and white goods to store user preferences such as channel lists, volume curves, EQ presets, language settings, and parental-control PINs. The 32 Kbyte capacity holds thousands of preference entries, and the byte-write capability allows single-byte updates without erasing an entire page. The SOIC-8 package is JEDEC-standard and compatible with high-volume SMT lines. Unlike internal MCU EEPROM, an external M24256-BWMN6TP frees the host microcontroller's internal Flash for firmware, reducing overall BOM cost.
Recommended
IoT Sensor Hub Configuration Memory
In IoT sensor hubs and edge gateways, the M24256-BWMN6TP stores network credentials (SSID, WPA keys), device-specific certificates, LoRaWAN DevEUI/AppKey, and per-sensor calibration curves. The 1 MHz I²C bus allows fast credential loading at boot, while the byte-write granularity simplifies secure-storage updates. The 8-SOIC footprint is small enough for compact sensor modules yet hand-solderable for prototyping. The three hardware address pins allow multiple EEPROMs to coexist on a sensor hub I²C bus for security and data partitions.
Recommended
Medical Device Event Log Retention
Medical infusion pumps, patient monitors, and diagnostic devices use the M24256-BWMN6TP for non-volatile retention of event logs, alarm history, and last-known-good configuration. The -40 °C to +85 °C industrial temperature range supports clinical environments, and the >40-year data retention ensures audit trails survive the device's service life. The hardware WP pin provides regulatory tamper-protection: once sealed, calibration values cannot be overwritten. The I²C interface simplifies certification by allowing the host MCU to read logs over a standard digital interface.
Recommended
Automotive Accessory Identification
Aftermarket and accessory automotive modules use the M24256-BWMN6TP to store module ID, vehicle-fitment tables, and firmware revision history. While the standard part is industrial-grade (-40 °C to +85 °C), the same SOIC-8 footprint accepts the AEC-Q100-qualified M24256-DR/DW variants for under-hood applications. The three hardware address pins allow multiple accessories (radio, dash cam, OBD reader) to share a single I²C diagnostic bus. Byte-level write capability simplifies in-field firmware-compatibility flag updates during service campaigns.
Recommended
Recommended Products Summary
Engineering reference data for M24256-BWMN6TP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | M24256-BWMN6TP/A | M24256-BRMN6TP | AT24C256C-SSHL-T | BR24G256F-3 | 24LC256-I/SN |
|---|---|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | Microchip Technology | ROHM Semiconductor | Microchip Technology |
| Package | SOIC-8 (SO-8, 150-mil) | SOIC-8 - same | SOIC-8 - same | SOIC-8 - same | SOIC-8 - same | SOIC-8 - same |
| Memory Size | 256 Kbit (32 K × 8) | 256 Kbit | 256 Kbit | 256 Kbit | 256 Kbit | 256 Kbit |
| Max Clock Frequency | 1 MHz | 1 MHz | 1 MHz | 1 MHz | 1 MHz | 400 kHz |
| Min VCC | 2.5 V | 2.5 V | 1.8 V | 1.8 V | 1.6 V | 2.5 V |
| Max VCC | 5.5 V | 5.5 V | 5.5 V | 5.5 V | 5.5 V | 5.5 V |
| Write Endurance | 1 M cycles | 1 M cycles | 1 M cycles | 1 M cycles | 1 M cycles | 1 M cycles |
| Operating Temperature | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C | -40 °C to +85 °C |
Key Differentiators
- Three hardware Chip Enable pins supporting 8 devices per bus (vs AT24C256C-SSHL-T)
- 1 MHz Fast-mode Plus I²C bus support (vs 24LC256-I/SN)
- Hardware Write Protect pin for tamper-resistance (vs BR24G256F-3)
Design Notes
Decouple VCC with a 0.1 µF ceramic capacitor placed within 5 mm of pin 8. The M24256-BWMN6TP draws brief inrush currents during internal charge-pump activity for write cycles; bulk decoupling is not normally required. For multi-EEPROM I²C buses, place the decoupling cap on each device individually to prevent bus-induced supply droop. Hold SDA and SCL low during power-up ramp to avoid spurious start-conditions that could leave the state machine in an indeterminate state - per STMicroelectronics datasheet recommendations.
Keep I²C traces (SDA, SCL) short and parallel, with ground plane on the layer directly beneath. Series resistors (typically 100 Ω-1 kΩ) on SDA and SCL near the MCU reduce ringing and allow bus arbitration with multiple masters. Place pull-up resistors (typically 4.7 kΩ for 1 MHz bus with multiple devices) close to the MCU side, not at the EEPROM end, to provide clean rising edges during ACK/NACK handshakes. The three Chip Enable pins (E0/E1/E2) must be tied directly to VCC or GND - they have no internal pull-up and floating inputs cause unpredictable addressing.
Do not exceed 1 MHz clock frequency with multiple devices on the bus; capacitive loading from cable or many devices slows edges and forces lower bus speeds. Do not leave the WP pin floating - it must be tied low (write enabled) or high (upper quadrant protected). Always wait for tWR (typically 5 ms) after a write command before issuing the next I²C transaction, or use ACK polling by sending a start-condition and checking for ACK. Operating at VCC below 2.5 V on this -BW variant will cause VCC-min violations; use the -BR or -BF variant for low-voltage rails.
Estimated: at 1 MHz I²C clock with 8 devices on a 30 cm bus, total capacitance can exceed 200 pF, slowing edges below acceptable rise times with 4.7 kΩ pull-ups. For long buses or many devices, reduce pull-up resistor values to 2.2 kΩ or 1 kΩ, or use bus repeaters. Place a guard ground trace between SDA and SCL to reduce crosstalk. The SDA line is open-drain; the MCU must release SDA high and let the pull-up resistor do the work - never actively drive SDA high.
Compliance Information
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified - use M24256-DR or M24256-DW variants for automotive grade.
