Microchip Technology 25LC320AT-E/SN

Overview

25LC320AT-E/SN from Microchip Technology Inc. is a 32-Kbit SPI Serial EEPROM with 4096 × 8-bit organization, 32-byte page size, and AEC-Q100 qualified Extended temperature range (−40°C to +125°C). It operates up to 10 MHz at 4.5–5.5 V, supports hardware write protection via WP pin, and delivers >1M erase/write cycles with >200-year data retention - deployed in automotive body control modules for configuration storage.

For engineers reviewing the 25LC320AT-E/SN datasheet, 25LC320AT-E/SN pinout, 25LC320AT-E/SN application, or 25LC320AT-E/SN equivalent, key selection criteria include SPI timing compliance at 125°C, block-level write protection granularity (none/¼/½/all), HOLD pin behavior during interrupt servicing, and SO high-impedance tri-state control during CS deassertion.

Technical Context

The 25LC320AT-E/SN 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 active operation. Its internal architecture includes an 8-bit instruction register, page latches, and HV generator for EEPROM programming - all controlled by serial clock (SCK) edges: data latched on rising SCK, SO updated after falling SCK.

Write operations require explicit WREN instruction before WRITE, followed by CS high to initiate self-timed internal write cycle (≤5 ms). STATUS register (RDSR/WRSR) enables dynamic control of BP0/BP1 block protection bits and WPEN hardware write-enable gating - critical for fail-safe firmware update sequences in automotive ECUs.

Key Specifications

Pinout & Package

25LC320AT-E/SN uses an 8-lead narrow SOIC package (SN), 3.90 mm body width, with JEDEC MS-012AC footprint. Pin 1 is marked with dot or bevel; pin 1 location confirmed per Microchip Drawing C04-057-SN Rev F.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA320AT-I/SN, the 25LC320AT-E/SN trades 1.8V compatibility for AEC-Q100 qualification and guaranteed 125°C operation - essential for automotive BCU deployment. Versus AT25DF321A-SHN-T, it offers simpler SPI protocol, deterministic 5ms writes, and HOLD functionality critical for real-time interrupt handling.

Availability

25LC320AT-E/SN is available at Aetrix Electronics and suitable for automotive electronics, industrial programmable logic controllers, and medical device calibration systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 25LC320AT-E/SN 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, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25LC320A family targets automotive and industrial applications demanding high-reliability nonvolatile storage with SPI simplicity, hardware write protection, and extended temperature operation - designed specifically for ECU configuration, sensor calibration, and firmware parameter retention.

FAQ

What is the maximum SPI clock frequency supported by the 25LC320AT-E/SN across its full voltage and temperature range?

The 25LC320AT-E/SN supports up to 10 MHz SPI clock frequency at VCC = 4.5–5.5 V and TA = −40°C to +125°C. At lower voltages (2.5–4.5 V), maximum frequency reduces to 5 MHz; below 2.5 V, it drops to 3 MHz. These limits are defined in Table 1-2 AC Characteristics and ensure timing margin compliance under worst-case conditions. The 25LC320AT-E/SN must be operated within these bounds to guarantee reliable read/write sequencing.

How does the HOLD pin function during an active SPI transaction on the 25LC320AT-E/SN?

The HOLD pin on the 25LC320AT-E/SN suspends serial communication mid-sequence without resetting the internal address pointer or command state. When pulled low while SCK is low, SO immediately enters high-impedance, and subsequent SI/SCK transitions are ignored until HOLD returns high - enabling host MCUs to service time-critical interrupts. The 25LC320AT-E/SN resumes exactly where it left off upon HOLD release, preserving full transaction integrity.

What write protection mechanisms are implemented in the 25LC320AT-E/SN, and how do they interact?

25LC320AT-E/SN implements dual-layer write protection: software-controlled STATUS register bits (BP0/BP1) for block-level array protection, and hardware-based WP pin gating enabled only when WPEN=1. When WP=low and WPEN=1, writes to nonvolatile STATUS bits are blocked - but array reads and writes remain functional. This layered scheme allows secure bootloader partitions while permitting runtime parameter updates, and is fully documented in Tables 3-3 and 3-4 of the 25LC320AT-E/SN datasheet.

Is the 25LC320AT-E/SN pin-compatible with other members of the 25XX320A family, such as the 25AA320AT-I/SN?

Yes, the 25LC320AT-E/SN is pin-compatible and functionally compatible with the 25AA320AT-I/SN and all other 25XX320A variants in the same package (e.g., SN). Both share identical 8-pin SOIC layout, SPI instruction set, STATUS register map, and timing specifications - differing only in VCC range (2.5–5.5 V vs. 1.8–5.5 V) and temperature grade (E vs. I). This allows drop-in replacement in existing designs where extended temperature operation is required.

What is the purpose of the "page write" limitation in the 25LC320AT-E/SN, and how should firmware handle it?

The 25LC320AT-E/SN restricts page writes to 32-byte boundaries: attempting to write across a page boundary causes data to wrap to the start of the current page instead of advancing. Firmware must calculate physical page addresses (base = (address >> 5) << 5) and split multi-page writes accordingly. This constraint ensures atomicity within each 32-byte buffer and prevents unintended overwrites - a requirement explicitly stated in Figure 3-3 and Section 3.3 of the 25LC320AT-E/SN datasheet.