Microchip Technology 25LC320AX-E/ST

Overview

25LC320AX-E/ST 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 at up to 10 MHz clock frequency with 5 mA read/write current at 5.5 V and features hardware write protection via WP pin and STATUS register control. It is used in automotive body control modules for storing calibration data and configuration parameters.

For engineers reviewing the 25LC320AX-E/ST datasheet, 25LC320AX-E/ST pinout, 25LC320AX-E/ST application, or 25LC320AX-E/ST equivalent, key selection criteria include SPI timing compliance at 125°C, block-level write protection granularity (0%, 25%, 50%, or 100% array), HOLD pin functionality for interrupt-safe bus arbitration, and guaranteed >1 million erase/write cycles with >200-year data retention.

Technical Context

The 25LC320AX-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, and VCC/VSS. 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 are self-timed (≤5 ms) and require explicit WREN instruction before WRITE or WRSR; the HOLD pin suspends ongoing serial transfers without resetting the address pointer, enabling deterministic host interrupt handling while preserving transaction state.

Key Specifications

Pinout & Package

25LC320AX-E/ST is supplied in an 8-lead TSSOP package (3.0 mm × 4.4 mm, 0.65 mm pitch) with exposed pad optional grounding. Pin numbering follows standard TSSOP orientation (pin 1 = CS, top-left corner marked dot).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC320AX-E/ST, the 25LC320AT-I/ST offers identical functionality at lower cost but lacks AEC-Q100 validation, while AT25DF321A-SH-B provides greater capacity and speed at the expense of pin compatibility and added firmware complexity.

Availability

25LC320AX-E/ST is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLCs, and medical device calibration systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 25LC320AX-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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and memory products, with global manufacturing and quality certifications including ISO/TS 16949 and AEC-Q200.

The 25LC320A family is designed for automotive and industrial applications requiring robust, low-power serial EEPROM with hardware write protection and extended temperature operation.

FAQ

What is the maximum SPI clock frequency supported by the 25LC320AX-E/ST?

The 25LC320AX-E/ST supports up to 10 MHz SPI clock frequency when VCC is between 4.5 V and 5.5 V. At lower supply voltages (2.5–4.5 V), the maximum clock drops to 5 MHz, and at 1.8–2.5 V it is limited to 3 MHz. These derating steps ensure setup/hold timing margins are maintained across voltage and temperature extremes. The 25LC320AX-E/ST datasheet specifies AC characteristics for each VCC range separately.

Does the 25LC320AX-E/ST require external pull-up resistors on SI, SO, or HOLD pins?

No, the 25LC320AX-E/ST does not require external pull-ups on SI, SO, or HOLD. SI is CMOS input with ±1 µA leakage and accepts standard logic levels; SO is open-drain with internal weak pull-up disabled by default - external pull-up is needed only if driving multiple loads or long traces. HOLD is active-low CMOS input; pull-up is optional for fail-safe high state but not mandatory per datasheet recommendations.

How does the HOLD pin function during an ongoing read or write operation in the 25LC320AX-E/ST?

When HOLD is pulled low during an active SPI transaction, the 25LC320AX-E/ST immediately tri-states SO and ignores further SI/SCK transitions while preserving the internal address pointer and command state. Communication resumes from the exact byte/bit position upon HOLD returning high (with SCK low). This allows host MCUs to service time-critical interrupts without losing EEPROM transaction context - a feature confirmed in DS20001828H Figure 1-1 and Section 2.6.

Can the 25LC320AX-E/ST be used with 1.8 V microcontrollers?

No, the 25LC320AX-E/ST has a minimum VCC of 2.5 V and is not rated for 1.8 V operation. While the related 25AA320A variant supports 1.8–5.5 V, the 25LC320A family (including 25LC320AX-E/ST) is specified only from 2.5 V to 5.5 V. Using it below 2.5 V may result in unreliable read/write behavior or failure to meet AC timing specifications per Table 1-1 and Table 1-2 of DS20001828H.

What write protection mechanisms are implemented in the 25LC320AX-E/ST?

The 25LC320AX-E/ST implements three layered write protection: (1) software-controlled STATUS register bits (BP0/BP1) for 0%/25%/50%/100% array locking; (2) hardware WP pin that disables STATUS register writes when WPEN=1; and (3) power-on reset of the write-enable latch. All mechanisms are documented in Sections 3.5–3.6 and Table 3-4 of DS20001828H, ensuring robust defense against accidental or malicious writes.