Microchip Technology 25AA128-I/SN

Overview

25AA128-I/SN from Microchip Technology is a 128 Kbit SPI Serial EEPROM with 16,384 × 8-bit organization, 64-byte page size, and industrial temperature range (–40°C to +85°C). It operates from 1.8V to 5.5V, supports up to 10 MHz clock at 4.5–5.5V, and delivers 5 µA standby current - enabling low-power data logging in battery-backed microcontroller systems.

For engineers reviewing the 25AA128-I/SN datasheet, 25AA128-I/SN pinout, 25AA128-I/SN application, or 25AA128-I/SN equivalent, key selection criteria include VCC range compatibility (1.8–5.5V), SPI timing margins across voltage tiers, hardware write protection via WP pin and STATUS register, HOLD functionality for interrupt-safe bus arbitration, and industrial-grade reliability (1M endurance, >200-year retention).

Technical Context

The 25AA128-I/SN implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, SI, SO, WP, HOLD, VCC, and VSS. Its internal architecture includes a 64-byte page latch, status register with WIP/WEL/BP0/BP1 bits, and high-voltage generator for EEPROM programming.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms). Block protection is configurable via BP0/BP1 bits to lock none, 1/4, 1/2, or all of the memory array - independent of software-controlled write-enable state.

Key Specifications

Pinout & Package

25AA128-I/SN is packaged in an 8-lead narrow SOIC (SN) with 1.27 mm pitch, 3.90 mm body width, and JEDEC MS-012AC compliant footprint. Pin 1 is marked with a beveled corner or dot; exposed pad is absent in SN package.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with 25LC128-I/SN, the 25AA128-I/SN offers broader voltage flexibility (1.8V support) critical for mixed-signal systems, while AT25DF041A-SHN-B trades pin compatibility and legacy SPI simplicity for higher density and faster throughput - making it unsuitable as a direct alternative without firmware and hardware revision.

Availability

25AA128-I/SN is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, medical infusion pumps, and smart energy meters requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for 25AA128-I/SN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology is a leading provider of microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25AA128-I/SN belongs to Microchip's serial EEPROM product line, engineered for reliable, low-power nonvolatile storage in cost-sensitive embedded systems where SPI interface simplicity and industrial-grade endurance are essential.

FAQ

What is the minimum supply voltage required for reliable operation of the 25AA128-I/SN?

The 25AA128-I/SN operates reliably down to 1.8V across its full industrial temperature range (–40°C to +85°C). Below 1.8V, read/write functionality is not guaranteed per specification; DC characteristics like VIH/VIL thresholds and ICC values are characterized only from 1.8V upward. Always verify actual VCC rail stability under load before deploying in 1.8V systems.

Does the 25AA128-I/SN support SPI Mode 1,1 or only Mode 0,0?

The 25AA128-I/SN supports only SPI Mode 0,0 (CPOL = 0, CPHA = 0), where data is sampled on the rising edge of SCK and output on the falling edge. Attempting Mode 1,1 communication will result in misaligned bit sampling and corrupted transfers. The device does not implement clock polarity or phase inversion logic.

How does the HOLD pin behave during an active write cycle?

The HOLD pin has no effect on an ongoing internal write cycle (TWC ≤ 5 ms); once initiated by CS rising edge, the write proceeds to completion regardless of HOLD state. However, HOLD can pause read or instruction sequences mid-transfer. During HOLD assertion, SO enters high-impedance and SI/SCK inputs are ignored except CS.

Can the 25AA128-I/SN be used in automotive applications requiring AEC-Q100 qualification?

Yes - the 25AA128-I/SN is explicitly AEC-Q100 qualified for automotive applications, as confirmed in the Device Selection Table and Packaging Information sections of DS20001831F. This qualification covers stress testing for temperature cycling, humidity bias, and mechanical shock, validating its use in body control, infotainment, and powertrain subsystems.

What happens if a page write crosses a 64-byte boundary on the 25AA128-I/SN?

If a page write command attempts to cross a 64-byte boundary (e.g., writing 10 bytes starting at address 0x003E), the data wraps around to the start of the same page (0x0000) instead of advancing to the next page. This overwrites previously written bytes in that page. Firmware must enforce address alignment or split multi-page writes manually to prevent unintended data loss.