Microchip Technology 25LC128T-E/SM

Overview

25LC128T-E/SM from Microchip Technology Inc. is a 128 Kbit SPI Serial EEPROM with 16,384 × 8-bit organization, 64-byte page size, and 10 MHz max clock (at V_CC ≥ 4.5V). It operates across –40°C to +125°C (Extended temperature grade), supports hardware write protection via WP pin and STATUS register, and delivers 1,000,000 erase/write cycles with >200-year data retention - used for firmware storage, calibration data, and configuration backup in automotive control modules.

For engineers reviewing the 25LC128T-E/SM datasheet, 25LC128T-E/SM pinout, 25LC128T-E/SM application, or 25LC128T-E/SM equivalent, key selection criteria include its extended-temperature qualification (AEC-Q100), 2.5V–5.5V supply range, HOLD functionality for interrupt-safe SPI pauses, block-level write protection (0%/25%/50%/100%), and TSSOP-8 packaging with industry-standard land pattern compatibility.

Technical Context

The 25LC128T-E/SM implements a standard SPI Mode 0,0 interface (CPOL = 0, CPHA = 0) with separate SI/SO lines and CS-controlled device selection. 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 - enabling precise control over write enable state and memory segment protection.

It features dual-layer data protection: power-on reset clears the write enable latch, and hardware write protection engages only when both WP pin is low and WPEN bit is set. The HOLD pin suspends ongoing SPI transfers without resetting the sequence, allowing host microcontrollers to service higher-priority interrupts while preserving transaction context.

Key Specifications

Pinout & Package

25LC128T-E/SM is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, JEDEC MO-153 compliant, body dimensions 4.4 mm × 3.0 mm × 1.2 mm. Pin 1 is marked with a dot; exposed pad is not present in TSSOP variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC128T-E/SM, the 25LC128-I/SN offers identical functionality at lower temperature grade and cost, while AT25DF128A-SHN-B provides greater density and speed but demands full hardware and software requalification - making the TSSOP-8 Extended-grade variant optimal for automotive and harsh-environment deployments requiring proven reliability and minimal integration risk.

Availability

25LC128T-E/SM is available at Aetrix Electronics and suitable for automotive ECU firmware storage, industrial PLC configuration backup, and medical device calibration data retention requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 25LC128T-E/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, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LC128 belongs to Microchip's serial EEPROM product line, engineered for robust, low-power nonvolatile data storage in automotive, industrial, and medical systems where reliability, long-term data integrity, and extended temperature operation are critical.

FAQ

What is the maximum clock frequency supported by the 25LC128T-E/SM?

The 25LC128T-E/SM supports up to 10 MHz SPI clock frequency when V_CC is 4.5V–5.5V. At 2.5V–4.4V, the maximum clock drops to 5 MHz, and it is not rated for 1.8V operation - unlike the 25AA128 variant. This voltage-dependent timing ensures signal integrity and write reliability across its specified supply range.

Does the 25LC128T-E/SM have built-in write protection, and how is it configured?

Yes, the 25LC128T-E/SM includes both software and hardware write protection. Block protection (BP0/BP1 bits) controls write access to 0%, 25%, 50%, or 100% of memory. Hardware protection activates only when the WP pin is low AND the WPEN bit in the STATUS register is set - preventing writes to nonvolatile STATUS bits while allowing normal array writes otherwise.

What does the "T-E/SM" suffix indicate in the 25LC128T-E/SM part number?

The "T" denotes temperature grade coding, "E" specifies Extended temperature range (–40°C to +125°C), and "SM" identifies the 8-lead TSSOP package per Microchip's standard marking convention. This exact suffix confirms AEC-Q100 qualification, TSSOP-8 mechanical form factor, and compliance with automotive reliability standards.

Can the 25LC128T-E/SM be used in a 3.3V system, and what are the implications?

Yes, the 25LC128T-E/SM is fully compatible with 3.3V systems: its 2.5V–5.5V V_CC range covers 3.3V nominal supplies, and AC timing parameters (e.g., 5 MHz max clock, 200 ns CS hold time) are guaranteed at this voltage. System designers must ensure logic-level compatibility - SI/SO operate at 3.3V CMOS levels, matching standard 3.3V MCU SPI peripherals.

How does the HOLD pin function during an active SPI transaction on the 25LC128T-E/SM?

The HOLD pin on the 25LC128T-E/SM suspends an ongoing SPI transaction without resetting the internal state: when pulled low while SCK is low, SI/SO/SCK enter high-impedance, and the device pauses exactly where it left off. Resuming requires bringing HOLD high while SCK remains low - then communication continues from the same bit position, preserving full transaction context for real-time interrupt handling.