Microchip Technology 25AA320AXT-I/ST

Overview

25AA320AXT-I/ST from Microchip Technology Inc. is a 32-Kbit SPI Serial EEPROM with 4096 × 8-bit organization, 32-byte page size, and industrial temperature range (–40°C to +85°C). It operates from 1.8V to 5.5V, supports up to 10 MHz clock frequency at 4.5–5.5V, and delivers 5 µA standby current. It is used in embedded systems for nonvolatile parameter storage, firmware configuration, and calibration data retention.

For engineers reviewing the 25AA320AXT-I/ST datasheet, 25AA320AXT-I/ST pinout, 25AA320AXT-I/ST application, or 25AA320AXT-I/ST equivalent, key selection criteria include SPI interface compatibility, write-protection flexibility (BP0/BP1), HOLD functionality for interrupt-safe operation, AEC-Q100 qualification, and MSOP-8 package suitability for space-constrained PCB layouts.

Technical Context

The 25AA320AXT-I/ST implements a standard SPI Mode 0,0/Motorola-compatible serial interface with separate SI (data in) and SO (data out) lines, CS-controlled selection, and SCK-synchronized transfers. It uses an internal high-voltage generator for EEPROM programming and includes a status register with WIP, WEL, BP0, BP1, and WPEN bits.

Its architecture supports byte and page writes (up to 32 bytes within one 32-byte page boundary), self-timed internal write cycles (≤5 ms), and hardware-assisted write protection via the WP pin combined with the WPEN bit. The HOLD pin enables pausing of ongoing SPI transactions without losing state or requiring reinitialization.

Key Specifications

Pinout & Package

25AA320AXT-I/ST is packaged in an 8-lead MSOP (Mini Small Outline Package) with 0.150-inch body width and gull-wing leads. Pin 1 is marked by a beveled corner or dot; the exposed pad is not present in MSOP variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC320AT-I/ST, the 25AA320AXT-I/ST enables 1.8V operation in ultra-low-power systems; compared with AT25DF321A-SSH-T, it provides true byte-addressable, wear-leveling-free EEPROM behavior ideal for infrequent, small-data updates.

Availability

25AA320AXT-I/ST is available at Aetrix Electronics and suitable for automotive body electronics, medical infusion devices, and industrial PLC I/O modules requiring stable component supply, long-lifecycle support, and AEC-Q100-compliant nonvolatile memory.

Supply support for 25AA320AXT-I/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 microcontroller, mixed-signal, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25AA320A family is part of Microchip's serial EEPROM product line, designed specifically for reliable, low-power, SPI-based nonvolatile data storage in automotive, industrial, and medical applications where data integrity and long-term retention are critical.

FAQ

What is the maximum clock frequency supported by the 25AA320AXT-I/ST?

The 25AA320AXT-I/ST supports up to 10 MHz clock frequency when VCC is between 4.5V and 5.5V. At lower supply voltages (2.5V ≤ VCC < 4.5V), the maximum clock rate drops to 5 MHz, and at 1.8V ≤ VCC < 2.5V, it is limited to 3 MHz. These limits ensure reliable setup/hold timing margins across voltage and temperature ranges, as specified in Table 1-2 of the DS20001828H datasheet. The 25AA320AXT-I/ST maintains full functionality across this entire voltage range without configuration changes.

Does the 25AA320AXT-I/ST require external pull-up resistors on its SPI lines?

The 25AA320AXT-I/ST does not require external pull-ups on SI, SCK, or CS - these inputs have CMOS-compatible thresholds and sufficient noise immunity. However, SO is an open-drain–like tri-state output and may benefit from a weak pull-up (e.g., 10 kΩ) on shared buses to prevent floating states during CS high or HOLD low. The 25AA320AXT-I/ST datasheet specifies no mandatory pull-ups, but system-level signal integrity analysis should guide final implementation.

How does the HOLD function operate during an active SPI transaction in the 25AA320AXT-I/ST?

The HOLD function in the 25AA320AXT-I/ST suspends SPI communication immediately upon a high-to-low transition of the HOLD pin while SCK is low. During hold, SI and SCK transitions are ignored, SO enters high-impedance, and the internal address pointer and instruction state are preserved. Resuming requires bringing HOLD high while SCK remains low; communication continues from the exact bit position where it paused. This behavior is fully defined in Section 2.6 and Figure 1-1 of the 25AA320AXT-I/ST datasheet.

Can the 25AA320AXT-I/ST be used in systems powered by 1.8V logic?

Yes, the 25AA320AXT-I/ST is fully specified for 1.8V operation (VCC = 1.8V to 5.5V), supporting SPI clock rates up to 3 MHz and meeting all DC/AC timing specifications at that voltage. Its 1.8V compatibility distinguishes it from the 25LC320A variant (min 2.5V), making the 25AA320AXT-I/ST suitable for battery-powered IoT sensors and ultra-low-power microcontroller systems. All features - including HOLD, WP, and status register access - remain functional at 1.8V.

What write protection mechanisms are implemented in the 25AA320AXT-I/ST?

The 25AA320AXT-I/ST implements three layered write protections: (1) software-controlled write enable latch (WREN/WRDI), reset on power-up; (2) nonvolatile block protection bits (BP0/BP1) enabling 0%, 25%, 50%, or 100% array lock; and (3) hardware write-protect via WP pin, enabled only when WPEN bit is set. These mechanisms operate independently - for example, WP low blocks STATUS register writes but not memory writes unless WPEN=1. All protections are documented in Sections 3.5–3.6 and Table 3-4 of the 25AA320AXT-I/ST datasheet.