Microchip Technology 25LC128XT-E/ST

Overview

25LC128XT-E/ST from Microchip Technology 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 configuration storage.

For engineers reviewing the 25LC128XT-E/ST datasheet, 25LC128XT-E/ST pinout, 25LC128XT-E/ST application, or 25LC128XT-E/ST equivalent, key selection criteria include its extended-temperature SPI EEPROM functionality, 2.5–5.5 V supply range, TSSOP-8 package compatibility, and block-level write protection granularity (none/¼/½/all array).

Technical Context

The 25LC128XT-E/ST implements a standard SPI Mode 0,0 interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, and HOLD for full protocol support. Its internal architecture includes a page latch buffer, HV generator for EEPROM programming, and status register with WIP, WEL, BP0/BP1, and WPEN bits.

Write operations require explicit WREN instruction before WRITE or WRSR commands; page writes are limited to 64 bytes within a single physical page boundary (e.g., 0x0000–0x003F), and crossing boundaries causes wraparound. The HOLD pin suspends ongoing serial transfers without resetting the sequence, enabling interrupt servicing in real-time microcontroller systems.

Key Specifications

Pinout & Package

25LC128XT-E/ST is packaged in an 8-Lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, JEDEC MO-153 compliant, and marked "25LC128I" with date code and traceability. The exposed pad is not electrically connected and may be left floating or tied to VSS for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC128-I/ST, the 25LC128XT-E/ST adds AEC-Q100 qualification and extended temperature operation, making it mandatory for automotive under-hood use; versus AT25DF128A-SHB-T, it retains legacy SPI simplicity and broader voltage tolerance but trades off peak throughput for robustness and ease of migration.

Availability

25LC128XT-E/ST is available at Aetrix Electronics and suitable for automotive electronics, industrial control systems, and medical device manufacturing requiring stable component supply across long product lifecycles.

Supply support for 25LC128XT-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 design and manufacturing operations.

The 25LC128XT-E/ST belongs to Microchip's serial EEPROM product line, engineered specifically for automotive and industrial applications demanding extended temperature operation, high endurance, and robust SPI interface compliance.

FAQ

What is the maximum clock frequency supported by the 25LC128XT-E/ST?

The 25LC128XT-E/ST supports up to 10 MHz clock frequency when VCC is between 4.5 V and 5.5 V. At 2.5–4.5 V, the maximum clock drops to 5 MHz. These limits are defined in Table 1-2 AC Characteristics and ensure reliable setup/hold timing for SI/SO data sampling. Exceeding them risks read/write corruption, especially at temperature extremes.

Does the 25LC128XT-E/ST support 1.8 V operation?

No, the 25LC128XT-E/ST does not support 1.8 V operation. Its specified VCC range is 2.5 V to 5.5 V, as confirmed in the Device Selection Table and DC Characteristics section. For 1.8 V–5.5 V compatibility, Microchip's 25AA128 family (e.g., 25AA128-I/ST) is the appropriate alternative, but it lacks AEC-Q100 qualification.

How does the HOLD pin function during an active SPI transaction on the 25LC128XT-E/ST?

The HOLD pin on the 25LC128XT-E/ST suspends an ongoing SPI sequence when pulled low while SCK is low. During hold, SI, SCK, and SO enter high-impedance states and ignore input transitions except CS. To resume, HOLD must be raised while SCK is low. This preserves the exact byte position and internal state, enabling deterministic interrupt handling in time-critical MCU firmware.

What write protection options are available on the 25LC128XT-E/ST?

The 25LC128XT-E/ST provides dual-layer write protection: hardware-based via the WP pin (when WPEN=1) and software-configurable via BP0/BP1 bits in the STATUS register. BP0/BP1 allow locking none, the upper 1/4 (0x3000–0x3FFF), upper 1/2 (0x2000–0x3FFF), or the entire array (0x0000–0x3FFF), giving precise control over firmware update zones and calibration data integrity.

Is the 25LC128XT-E/ST pin-compatible with other 8-pin SPI EEPROMs like the 25AA128 series?

Yes, the 25LC128XT-E/ST is pin-compatible with the 25AA128 series in identical packages (e.g., TSSOP-8), sharing identical pin functions (CS, SO, WP, VSS, SI, SCK, HOLD, VCC) and layout. However, voltage range differs: 25AA128 supports 1.8–5.5 V, while 25LC128XT-E/ST requires 2.5–5.5 V. Interchangeability requires verifying VCC compliance and temperature grade suitability for the target application.