Microchip Technology 25LC128-E/ST

Overview

25LC128-E/ST from Microchip Technology Inc. is a 128 Kbit SPI Serial EEPROM with 16,384 × 8-bit organization, 64-byte page size, and AEC-Q100 qualified extended temperature operation (–40°C to +125°C). It supports up to 10 MHz clock at 4.5–5.5 V, features hardware write protection via WP pin and STATUS register, and delivers 1,000,000 erase/write cycles with >200-year data retention - used in automotive body control modules for calibration storage and fault log retention.

For engineers reviewing the 25LC128-E/ST datasheet, 25LC128-E/ST pinout, 25LC128-E/ST application, or 25LC128-E/ST equivalent, key selection considerations include its 8-lead TSSOP package, 2.5–5.5 V supply range, HOLD functionality for interrupt-safe SPI pausing, and block-level write protection (none/¼/½/all array).

Technical Context

The 25LC128-E/ST 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, HV generator for EEPROM programming, and status register with WIP, WEL, BP0/BP1, and WPEN bits.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal write cycle (≤5 ms), while read operations support sequential addressing with automatic address roll-over. Hardware write protection is enabled only when WP = low AND WPEN = 1; otherwise, full register and memory access remains available.

Key Specifications

Pinout & Package

25LC128-E/ST is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, JEDEC MO-153 compliant, marked "25LC128" on top with "E/ST" indicating Extended temperature grade and TSSOP package.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA128-I/ST, the 25LC128-E/ST trades 1.8 V compatibility for AEC-Q100 qualification and extended temperature range - critical for automotive use. Versus AT25DF041A-SSH-T, it offers deterministic HOLD-based interrupt handling and proven automotive reliability, albeit at lower density and single-data-line SPI speed.

Availability

25LC128-E/ST is available at Aetrix Electronics and suitable for automotive electronics, industrial programmable logic controllers, and medical device data logging requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 25LC128-E/ST 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 components, and memory solutions, headquartered in Chandler, Arizona, with global manufacturing and support infrastructure.

The 25LC128-E/ST belongs to Microchip's 25XX128 family of SPI EEPROMs, designed specifically for reliable, low-power nonvolatile storage in automotive, industrial, and medical systems where data integrity and long-term retention are mission-critical.

FAQ

What is the supply voltage range for the 25LC128-E/ST?

The 25LC128-E/ST operates from 2.5 V to 5.5 V DC. This range supports common industrial and automotive rails including 3.3 V and 5 V systems. Operation below 2.5 V is not guaranteed and may result in unreliable write cycles or STATUS register reads. The 25LC128-E/ST datasheet specifies AC and DC characteristics only within this defined window.

Does the 25LC128-E/ST support SPI Mode 1,1 or only Mode 0,0?

The 25LC128-E/ST supports only SPI Mode 0,0 (CPOL = 0, CPHA = 0): clock idles low, data sampled on rising edge, data changed on falling edge. It does not support Mode 1,1 or other variants. This is confirmed by the timing diagrams and functional description in DS20001831F, which define SI sampling on SCK rising edge and SO output valid after falling edge.

How does the HOLD pin function during an active SPI transaction on the 25LC128-E/ST?

When the HOLD pin is pulled low during an active SPI sequence (with CS low and SCK low), the 25LC128-E/ST pauses communication: SI, SCK, and SO enter high-impedance states, and internal state is preserved. To resume, HOLD must be raised while SCK is low. If SCK is high when HOLD is released, communication will not restart until the next SCK low-to-high transition.

Can the 25LC128-E/ST be used as a direct replacement for the 25LC128-I/ST in an existing design?

No - the 25LC128-E/ST is not a direct replacement for the 25LC128-I/ST due to differing temperature specifications: the -E suffix denotes Extended grade (–40°C to +125°C), while -I is Industrial (–40°C to +85°C). Electrical specs and pinout are identical, but thermal validation and qualification differ. Substitution requires requalification for operation above +85°C.

What happens if a page write crosses a 64-byte boundary on the 25LC128-E/ST?

If a page write command attempts to cross a 64-byte boundary (e.g., writing 10 bytes starting at address 0x003E), the 25LC128-E/ST wraps the excess bytes to the start of the same page (0x0000–0x003F), overwriting earlier data in that page. The device does not auto-advance to the next page. Application firmware must enforce page alignment to prevent unintended data corruption.