Microchip Technology 25AA128-I/MF

Overview

25AA128-I/MF from Microchip Technology Inc. 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 features hardware write protection via WP pin and STATUS register control. It is used in microcontroller-based systems for nonvolatile parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 25AA128-I/MF datasheet, 25AA128-I/MF pinout, 25AA128-I/MF application, or 25AA128-I/MF equivalent, this page delivers verified electrical specs, SPI timing constraints, HOLD/CS/WP functional behavior, package-specific pin mapping (TSSOP-8), and real-world design implications of page-write boundaries and WIP status polling.

Technical Context

The 25AA128-I/MF implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS low and HOLD high for normal operation. Its internal architecture includes a 64-byte page latch, EEPROM array with >200-year data retention, and a STATUS register with WIP, WEL, BP0/BP1, and WPEN bits.

Write operations require explicit WREN instruction before WRITE or WRSR commands; CS rising edge initiates self-timed internal write cycle (≤5 ms). Block protection is configurable to lock none, 1/4, 1/2, or all memory via BP0/BP1 bits, while hardware write protection engages only when WP = low and WPEN = 1.

Key Specifications

Pinout & Package

25AA128-I/MF is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with exposed pad option; pin 1 is marked by notch or dot, and the exposed pad may be connected to VSS or left floating per Microchip recommendation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC128-I/MF, the 25AA128-I/MF uniquely supports 1.8V operation and shares identical packaging and pinout, while AT25DF041A-MAU-T offers greater density at the cost of protocol incompatibility and loss of HOLD/WP hardware safety features.

Availability

25AA128-I/MF 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 sourcing.

Supply support for 25AA128-I/MF 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 microcontrollers, analog devices, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.

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

FAQ

What is the minimum VCC required for reliable operation of the 25AA128-I/MF?

The 25AA128-I/MF operates reliably from 1.8V to 5.5V. At 1.8V, maximum clock frequency is 3 MHz, and DC characteristics such as VOL and VOH shift accordingly-designs must verify timing margins using Table 1-2 AC specs for VCC < 2.5V. The 25AA128-I/MF is the only variant in the 25XX128 family supporting 1.8V operation.

How does the HOLD pin function during an active SPI read sequence in the 25AA128-I/MF?

When HOLD is pulled low during an active SPI read (with CS low and SCK toggling), the 25AA128-I/MF immediately tri-states SO, SI, and SCK, pauses the address counter, and ignores further input transitions except CS. To resume, HOLD must be raised while SCK is low-the device continues from the exact byte where it paused. This behavior is confirmed in DS20001831F Section 2.6 and Figure 1-1.

Can the 25AA128-I/MF be used in automotive applications, and what qualifications does it hold?

Yes-the 25AA128-I/MF is AEC-Q100 qualified for automotive Grade 2 (−40°C to +105°C ambient), and its industrial temperature grade (I) covers −40°C to +85°C operation. It meets RoHS requirements and has >4 kV HBM ESD rating, making it suitable for body control, infotainment, and ADAS subsystems where EEPROM reliability under thermal stress is critical.

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

If a page write command attempts to write across a 64-byte boundary (e.g., starting at address 0x003E and writing 4 bytes), the 25AA128-I/MF wraps the data to the start of the same page (0x0000), overwriting previously written bytes. This behavior is explicitly documented in DS20001831F Section 3.3 and requires firmware to enforce page-aligned writes or split multi-page transfers manually.

How is hardware write protection enabled on the 25AA128-I/MF?

Hardware write protection on the 25AA128-I/MF requires two conditions: the WPEN bit (bit 7) in the STATUS register must be set to 1 via WRSR command, and the WP pin (pin 3) must be held low. When both are true, writes to nonvolatile STATUS bits are blocked-but memory reads, byte writes, and page writes remain fully functional unless block protection bits (BP0/BP1) are also set.