Microchip Technology 25LC128-E/SM

Overview

25LC128-E/SM from Microchip Technology Inc. is a 128 Kbit SPI Serial EEPROM with 16,384 × 8-bit organization, 64-byte page size, and extended temperature operation (–40°C to +125°C). It features hardware write protection via WP pin and STATUS register, self-timed 5 ms max write cycles, and AEC-Q100 qualification for automotive applications.

For engineers reviewing the 25LC128-E/SM datasheet, 25LC128-E/SM pinout, 25LC128-E/SM application, or 25LC128-E/SM equivalent, this page delivers verified electrical specs, SPI timing constraints at 2.5V–5.5V, package-specific pin mapping for TSSOP-8, endurance data (1M cycles), and real-world use context for firmware storage and configuration retention in harsh environments.

Technical Context

The 25LC128-E/SM implements a standard SPI Mode 0,0/Master-Slave interface with separate SI (data-in) and SO (data-out) lines, CS-controlled selection, and HOLD pin for transaction suspension without reset. Its internal architecture includes a 64-byte page latch, status register with WIP/WEL/BP0/BP1 bits, and high-voltage generator for EEPROM programming.

It supports four block protection levels (none, 1/4, 1/2, or full array) via BP0/BP1 bits, hardware write protection enabled only when WPEN=1 and WP=low, and power-on default of disabled writes (WEL=0). The device operates across VCC = 2.5V–5.5V with clock frequencies up to 10 MHz at 4.5–5.5V, scaling down to 5 MHz (2.5–4.5V) and 3 MHz (1.8–2.5V).

Key Specifications

Pinout & Package

25LC128-E/SM is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, JEDEC MO-153 compliant, and marked "25LC128 I/SM" per Microchip's packaging specification C04-057-ST Rev D.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA128-I/SN, the 25LC128-E/SM provides guaranteed operation at 125°C and automotive qualification, while AT25DF041A-SSH-T offers greater density at the cost of SPI compatibility and pinout redesign - making 25LC128-E/SM optimal for drop-in replacement in existing AEC-Q100-compliant designs.

Availability

25LC128-E/SM is available at Aetrix Electronics and suitable for automotive ECU development, industrial PLC configuration storage, and medical device calibration retention requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 25LC128-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-E/SM belongs to Microchip's serial EEPROM product line, engineered specifically for robust, low-power, SPI-based nonvolatile storage in automotive, industrial, and medical applications demanding high reliability and extended temperature performance.

FAQ

What is the maximum SPI clock frequency supported by the 25LC128-E/SM?

The 25LC128-E/SM supports up to 10 MHz SPI clock frequency when VCC is 4.5V–5.5V, 5 MHz at 2.5V–4.5V, and 3 MHz at 1.8V–2.5V. These limits are defined in Table 1-2 of the DS20001831F datasheet and reflect guaranteed AC timing margins for reliable instruction decoding and data transfer. Exceeding these frequencies may cause command misreads or data corruption.

Does the 25LC128-E/SM require external pull-up resistors on its SPI lines?

No external pull-ups are required on SI, SO, or SCK for normal operation of the 25LC128-E/SM, as these pins are actively driven. However, CS and WP should be pulled high via 10 kΩ resistors in most designs to ensure defined logic states during power-up and idle periods. HOLD also benefits from a weak pull-up to prevent spurious pauses.

How does the HOLD function behave during an active write cycle in the 25LC128-E/SM?

The HOLD pin has no effect on an ongoing internal write cycle in the 25LC128-E/SM. Once a write is initiated (CS rising edge after valid WRITE command), the device completes the 5 ms self-timed erase-and-write sequence regardless of HOLD state. HOLD only suspends serial communication - it cannot interrupt or abort an active write.

Can the 25LC128-E/SM be used as a direct replacement for the 25LC128-I/SM?

No, the 25LC128-E/SM is not a direct replacement for the 25LC128-I/SM due to differing temperature specifications: the -E suffix denotes Extended grade (–40°C to +125°C) and AEC-Q100 qualification, while -I denotes Industrial grade (–40°C to +85°C) without automotive certification. Electrical and functional behavior is identical within their respective temperature ranges.

What happens to the write enable latch (WEL) after a successful write operation in the 25LC128-E/SM?

In the 25LC128-E/SM, the write enable latch (WEL) is automatically reset to '0' after any successful WRITE, WRSR, or WRDI instruction execution. This prevents unintended subsequent writes and enforces explicit reissuance of the WREN command before each new write sequence - a critical safety feature for data integrity.