AT24CSW020-UUM0B-T - 2Kb I2C Serial EEPROM with Security | Microchip
MPN: AT24CSW020-UUM0B-T ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.48 | $0.48 |
| 10 | $0.44 | $4.40 |
| 100 | $0.38 | $38.00 |
| 500 | $0.34 | $170.00 |
| 1,000 | $0.31 | $310.00 |
AT24CSW020-UUM0B-T Overview
What is an EEPROM? An EEPROM (Electrically Erasable Programmable Read-Only Memory) is a non-volatile memory device that retains stored data when power is removed and supports byte-level in-system erase and rewrite via an electrical interface, distinguishing it from one-time-programmable ROM and from flash memory which erases in larger blocks. EEPROMs typically connect via serial protocols such as I2C or SPI to keep pin count low, making them ideal for storing configuration parameters, calibration coefficients, and device identity in space-constrained designs. Within the broader taxonomy, the AT24CSW020 belongs to the serial EEPROM class -> non-volatile memory -> memory IC -> semiconductor device.
Key features include low-power CMOS technology, built-in power-on reset (POR) to suppress bus glitches, noise-suppression filters on the I2C inputs, and hardware/software write protection. The pre-programmed serial number is factory-locked and immutable, while a user-programmable security register (16 x 8 in the 2 Kb device) can store OEM-specific data behind SWP. The device supports byte-write and 16-byte page-write modes with automatic erase-before-write.
Internally, the AT24CSW020 uses a proprietary CMOS floating-gate cell array paired with an I2C slave state machine, a charge-pump row/column decoder, and a 32-bit ROM that holds the unique serial number. The 1 MHz Fast-Mode Plus-compatible interface uses 100 kHz Standard-Mode and 400 kHz Fast-Mode timing as legacy tiers, with a 450 ns access time measured from the SCL falling edge.
Typical applications include storing Wi-Fi/BLE pairing credentials in IoT modules, factory calibration coefficients in sensor boards, asset tracking with the unique serial number, accessory authentication in consumer electronics, and small-parameter storage in wearable devices. The WLCSP-4 package enables direct attachment on the back of a PCB or in ultra-small modules where a standard SOIC footprint is impossible.
When designing with this device, follow Microchip's PCB layout guidance: place decoupling capacitors close to the VCC ball, route SDA/SCL traces with matched impedance to the controller, and add external pull-up resistors sized to meet the I2C sink-current limit at 1 MHz. Pull-ups of 1 kohm to 4.7 kohm are typical at 3.3 V for Fast-Mode Plus operation.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for AT24CSW020-UUM0B-T — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AT24CSW020-UUM0B-T (same form factor and footprint) — differing in Memory Type, RoHS Status, Data Retention, MSL Level, Memory Organization.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AT24CSW010-UUM0B-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT24CSW020-SSHM-T
✅ Drop-In📋 Reference alternative (not in catalog)
AT24C02D-MAHM-T
✅ Drop-In✓ In Stock
$0.21 / Unit
View Datasheet →AT24C02D-SSHM-T
✅ Drop-In✓ In Stock
$0.17 / Unit
View Datasheet →24AA02E48-I/OT
✅ Drop-In✓ In Stock
$0.38 / Unit
View Datasheet →24LC02B-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
AT24CSW020-UUM0B-T Maximum Ratings & Electrical Characteristics
| Memory Type | Non-Volatile EEPROM |
| Memory Size | 2 Kbit (256 x 8) |
| Interface | I2C (2-wire) |
| Clock Frequency (Max) | 1 MHz |
| Access Time | 450 ns |
| Supply Voltage | 1.7 V to 3.6 V |
| Write Cycle Time | 5 ms (typical page write) |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 4-WLCSP (4-ball WLCSP) |
| Mounting Type | Surface Mount |
| Unique Serial Number | Factory pre-programmed 32-bit (per datasheet) |
| Security Register | Yes (user-programmable) |
| Write Protection | Hardware WP pin + Software Write Protection (SWP) |
| Power-On Reset (POR) | Built-in |
| MSL Level | 1 (per WLCSP handling guidelines) |
| RoHS Status | Compliant |
AT24CSW020-UUM0B-T Pin Configuration
| Pin A1 | VCC — Positive supply voltage (1.7 V to 3.6 V) |
| Pin B1 | SCL — I2C serial clock input (requires external pull-up to VCC) |
| Pin A2 | SDA — I2C serial data I/O (requires external pull-up to VCC) |
| Pin B2 | GND — Ground reference |
Typical Applications
AT24CSW020-UUM0B-T is suitable for 6 applications: IoT Module Identity Storage, Accessory Authentication in Consumer Electronics, Sensor Calibration Coefficient Storage, Wearable Device Configuration Storage, Industrial Asset Tracking Tags, Medical Device Parameter Memory.
IoT Module Identity Storage
The AT24CSW020-UUM0B-T fits IoT module identity storage because of its factory-pre-programmed 32-bit unique serial number, accessible through a dedicated I2C device address separate from the user memory area. This lets a Wi-Fi or BLE module host an immutable device identity at zero firmware cost. The 2 Kbit user area stores Wi-Fi credentials, BLE pairing keys, and X.509 client certificates. Per Atmel-8982F, the security register behind SWP enables tamper-resistant storage of authentication secrets. At 1.7 V to 3.6 V operation and sub-microamp standby, the device draws negligible current from battery-powered sensors. The WLCSP-4 footprint enables direct attachment on the underside of the host PCB in modules under 6 mm x 6 mm, freeing top-side space for the antenna.
Recommended
Accessory Authentication in Consumer Electronics
Accessory authentication benefits from the AT24CSW020's pre-programmed unique serial number plus the user-programmable security register, which together enable a secure challenge-response authentication flow. Per Atmel-8982F, the security register is 16 bytes in the 2 Kb variant, sufficient for an HMAC key or signed certificate chain. The host mainboard reads the serial number at boot and validates it against a server-side allow-list. Software Write Protection prevents field tampering with the security register, while the hardware WP pin provides a final physical lockout. Operating from 1.7 V to 3.6 V covers single-cell Li-ion and 3.3 V regulated rails typical of consumer peripherals. The 1 MHz I2C clock minimizes authentication latency at power-on, with 450 ns access time per the datasheet.
Recommended
Sensor Calibration Coefficient Storage
Sensor calibration storage requires a non-volatile medium that survives power cycles and supports in-field updates, both of which the AT24CSW020-UUM0B-T provides through its 2 Kbit byte-addressable EEPROM. The byte-write and 16-byte-page-write operations at 5 ms typical cycle time per Atmel-8982F allow per-unit calibration coefficients to be loaded at final test and re-tuned in the field. The WLCSP-4 footprint enables placement directly adjacent to the sensor die on a sensor module PCB, reducing trace length and bus capacitance. Hardware WP and SWP prevent accidental erasure during power-up brown-outs or I2C glitches. Industrial -40 C to +85 C operating range covers outdoor and automotive sensor applications.
Recommended
Wearable Device Configuration Storage
Wearable devices use the AT24CSW020-UUM0B-T to store user-specific configuration, last-used settings, and BLE pairing data in a non-volatile form factor. The 4-WLCSP package, occupying roughly 1 mm x 1 mm of PCB area, fits inside the tight enclosure of a fitness band or smartwatch. Per Atmel-8982F, the device draws less than 1 microampere in standby, preserving battery life when the wearable is idle. The 1.7 V minimum to supports coin-cell and small Li-ion batteries. The integrated power-on reset prevents partial-write corruption when the device is hot-plugged to a charger. The pre-programmed 32-bit serial number serves as a hardware-bound device identity for fitness platforms.
Recommended
Industrial Asset Tracking Tags
Industrial asset tracking tags leverage the AT24CSW020's unique 32-bit serial number to provide a globally unique identifier per tag, eliminating the need for factory programming of identity data. The user-programmable 2 Kbit memory stores service history, calibration timestamps, or signed firmware version info. Per Atmel-8982F, the SWP register prevents field overwrite of the calibration baseline. Industrial -40 C to +85 C operation covers outdoor and factory-floor environments. The WLCSP-4 footprint enables direct embedding inside RFID/NFC tag enclosures. Combined with a battery-backed RTC and an I2C host MCU, the device forms the data backbone of a long-life asset tag with a 10+ year service life.
Recommended
Medical Device Parameter Memory
Medical device parameter storage benefits from the AT24CSW020's byte-level write capability, software and hardware write protection, and the integrated security register for tamper-evident logs. Per Atmel-8982F, the SWP feature prevents accidental overwrites of clinician-set values. The pre-programmed serial number enables per-device traceability for FDA UDI compliance. The 1.7 V to 3.6 V supply covers 3.3 V regulated rails typical of portable medical instruments. The WLCSP-4 footprint fits inside compact handheld devices such as glucose meters, pulse oximeters, and connected inhalers. At 450 ns access time and 1 MHz I2C, parameter reads complete well within the latency budget of point-of-care diagnostic cycles.
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Recommended Products Summary
Engineering reference data for AT24CSW020-UUM0B-T — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AT24CSW010-UUM0B-T | AT24CSW020-SSHM-T | AT24C02D-MAHM-T | AT24C02D-SSHM-T | 24AA02E48-I/OT | 24LC02B-I/SN |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 4-WLCSP | 4-WLCSP - same | SOIC-8 (same die, different footprint) | 8-MAP (WLCSP-like) | SOIC-8 | SOT-23-6 | SOIC-8 |
| Memory Size | 2 Kbit (256 x 8) | 1 Kbit (128 x 8) | 2 Kbit (256 x 8) | 2 Kbit (256 x 8) | 2 Kbit (256 x 8) | 2 Kbit (256 x 8) | 2 Kbit (256 x 8) |
| Interface | I2C up to 1 MHz | I2C up to 1 MHz | I2C up to 1 MHz | I2C up to 1 MHz | I2C up to 1 MHz | I2C up to 400 kHz | I2C up to 400 kHz |
| Supply Voltage | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.7 V to 3.6 V | 1.8 V to 5.5 V | 2.5 V to 5.5 V |
| Pre-programmed Serial Number | Yes (32-bit unique) | Yes (32-bit unique) | Yes (32-bit unique) | No | No | Yes (48-bit EUI-48) | No |
| Security Register | Yes (user-programmable) | Yes | Yes | No | No | No | No |
| Write Protection | Hardware WP + Software (SWP) | Hardware WP + Software (SWP) | Hardware WP + Software (SWP) | Hardware WP only | Hardware WP only | Hardware WP only | Hardware WP only |
| 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 | -40 C to +85 C |
Key Differentiators
- Pre-programmed 32-bit unique serial number accessible via dedicated I2C device address (vs AT24C02D-MAHM-T)
- Integrated user-programmable security register with software write protection (SWP) (vs 24LC02B-I/SN)
- Smallest package footprint in Microchip 2 Kbit EEPROM lineup (vs AT24CSW020-SSHM-T)
Design Notes
WLCSP-4 packages have very small solder balls (~0.25 mm diameter) that are easily damaged by probe contact and mechanical flex. Per Atmel-8982F and IPC-7351 WLCSP guidelines, place the part away from board edges and avoid placing tall components within 1 mm of the WLCSP land pattern. Use NSMD (non-solder mask defined) pads with a 0.05 mm to 0.075 mm mask expansion to improve solder joint reliability. The PCB land pattern must use a 0.4 mm pitch consistent with the 4-ball WLCSP geometry; do not attempt to reuse a QFN land pattern.
Per Atmel-8982F, the AT24CSW020 requires external pull-up resistors on both SDA and SCL because the I2C drivers cannot pull the lines low-only (open-drain). At 1 MHz Fast-Mode Plus operation with VCC = 3.3 V, choose pull-ups in the 1 kohm to 4.7 kohm range to satisfy the 20 ns + 0.1 x Cbus rise-time budget. Add a 100 nF decoupling capacitor close to the VCC ball to suppress the noise burst during a write cycle; a 10 nF or 100 nF cap placed within 2 mm of VCC provides adequate local bypass. The device draws less than 1 microampere in standby, so the pull-ups dominate quiescent current.
Route SDA and SCL traces as a length-matched differential pair to within 5 mm even though I2C is single-ended, because at 1 MHz Fast-Mode Plus operation the rise/fall time budget is tight. Keep SDA/SCL traces short and route them on the same layer as the WLCSP-4 footprint to avoid via-via. Per Atmel-8982F reference schematics, route the traces over a continuous ground plane to control impedance and reduce EMI. Avoid routing the I2C lines parallel to high-current or high-frequency traces such as DC-DC switcher nodes.
At 1 MHz operation, the I2C bus is sensitive to capacitance; per Atmel-8982F, total bus capacitance (host pin + trace + WLCSP ball + external devices) should not exceed 200 pF to meet the Fast-Mode Plus rise/fall time spec. If the bus capacitance approaches 200 pF, lower the pull-up resistor value or use a bus accelerator. The WLCSP-4 ball adds approximately 1 pF to 3 pF; the host MCU's I2C pin adds 5 pF to 10 pF; trace capacitance is 2 pF to 5 pF per cm depending on stack-up. Always measure with an oscilloscope at the SDA/SCL pads before declaring the design passing.
Compliance Information
RoHS and lead-free compliance inferred from product page listing; REACH compliance per Microchip product declaration. Not AEC-Q100 qualified - this is a commercial/industrial-grade part. WLCSP-4 is MSL-1 per JEDEC J-STD-020.
