Microchip Technology 25AA128-I/SM

Overview

25AA128-I/SM 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 - used for nonvolatile parameter storage in microcontroller-based embedded systems requiring robust data retention.

For engineers reviewing the 25AA128-I/SM datasheet, 25AA128-I/SM pinout, 25AA128-I/SM application, or 25AA128-I/SM equivalent, this page provides verified electrical specs, SPI timing constraints, write-protection behavior, HOLD functionality, and package-specific pin mapping for the 8-lead TSSOP (SM) variant.

Technical Context

The 25AA128-I/SM implements a standard SPI Mode 0,0 interface with separate SI (data in) and SO (data out) lines, CS-controlled selection, and hardware-assisted HOLD suspension. Its internal architecture includes a 64-byte page latch, status register with WIP/WEL/BP0/BP1 bits, and on-chip high-voltage generator for EEPROM programming.

It supports byte and page writes (up to 64 bytes within one 64-byte boundary), self-timed internal write cycles (≤5 ms), and configurable block protection (none, 1/4, 1/2, or full array). Write enable requires explicit WREN instruction; WP pin + WPEN bit enables hardware write protection independent of software control.

Key Specifications

Pinout & Package

25AA128-I/SM is packaged in an 8-lead TSSOP (package code SM), with exposed pad optionally connected to VSS. Pin numbering follows standard top-view orientation (Pin 1 = CS, Pin 8 = VCC).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC128-I/SM, the 25AA128-I/SM uniquely supports 1.8V operation and shares identical packaging and pinout - enabling drop-in replacement in low-voltage designs. Versus AT25128B-SSHL-T, it offers 10× higher endurance, AEC-Q100 qualification, and industrial temperature assurance at the cost of slightly lower maximum clock speed.

Availability

25AA128-I/SM is available at Aetrix Electronics and suitable for smart meter firmware storage, medical device calibration data retention, and automotive body control module configuration requiring stable component supply across industrial and automotive production lifecycles.

Supply support for 25AA128-I/SM 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 Inc. is a leading provider of microcontroller, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25AA128 belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile storage in resource-constrained embedded systems across industrial, automotive, and medical markets.

FAQ

What is the minimum supply voltage required for 25AA128-I/SM operation?

The 25AA128-I/SM operates from 1.8V to 5.5V. At 1.8V, its maximum clock frequency is 3 MHz, and DC/AC specifications remain fully guaranteed across the industrial temperature range (–40°C to +85°C). This makes 25AA128-I/SM suitable for direct integration with 1.8V microcontrollers without level-shifting circuitry.

Does 25AA128-I/SM support page writes, and what is the maximum length?

Yes, 25AA128-I/SM supports page writes of up to 64 bytes - matching its page size. All bytes in a single page write must reside within the same 64-byte boundary (e.g., addresses 0x0000–0x003F); crossing the boundary causes wraparound within the current page. The 25AA128-I/SM completes each internal write cycle in ≤5 ms.

How does the HOLD pin function in 25AA128-I/SM, and what are its timing requirements?

The HOLD pin in 25AA128-I/SM suspends ongoing SPI communication without resetting the sequence. To activate HOLD, the pin must be pulled low while SCK is low; to resume, HOLD must be raised high while SCK remains low. During HOLD, SI/SO/SCK enter high-impedance, and transitions on those pins are ignored - preserving address and data state for MCU interrupt servicing.

Is 25AA128-I/SM AEC-Q100 qualified, and which grade applies?

Yes, 25AA128-I/SM is AEC-Q100 qualified for automotive applications. The "I" suffix denotes Industrial grade (–40°C to +85°C), and Microchip explicitly states AEC-Q100 qualification for the 25XX128 family in the device selection table and features list - confirming suitability for automotive body electronics and infotainment subsystems.

Can the WP pin protect only the STATUS register, or does it affect memory array writes?

The WP pin in 25AA128-I/SM - when enabled via the WPEN bit in the STATUS register - protects only the nonvolatile bits of the STATUS register (BP0, BP1, WPEN). Memory array writes remain fully functional regardless of WP state. This allows hardware-level prevention of accidental configuration changes while preserving full data write capability - a key distinction from array-level write protection controlled by BP bits.