Microchip Technology 25AA320A-I/ST

Overview

25AA320A-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 features hardware write protection via WP pin and STATUS register control. It is used in embedded systems for firmware parameter storage, calibration data retention, and configuration backup in microcontroller-based designs.

For engineers reviewing the 25AA320A-I/ST datasheet, 25AA320A-I/ST pinout, 25AA320A-I/ST application, or 25AA320A-I/ST equivalent, key selection criteria include SPI interface compatibility, 1.8V minimum VCC support, industrial-grade reliability (>1M endurance, >200-year data retention), and integrated HOLD/CS/WP control for robust bus arbitration and data integrity in power-constrained environments.

Technical Context

The 25AA320A-I/ST implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (data in) and SO (data out) lines, requiring CS, SCK, and optional HOLD/WP signals. Its internal architecture includes an 8-bit instruction register, page latches, and high-voltage generation circuitry for EEPROM programming - all managed by on-chip control logic without external components.

It supports sequential read, byte/page write, and STATUS register access (RDSR/WRSR), with self-timed internal write cycles completing in ≤5 ms. Block protection is configurable via BP0/BP1 bits to lock none, 1/4, 1/2, or full memory array, while WPEN enables or disables hardware write-protection based on the WP pin state.

Key Specifications

Pinout & Package

25AA320A-I/ST is packaged in an 8-lead TSSOP (Thin Shrink Small Outline Package) with 0.65 mm pitch, measuring 4.4 mm × 3.0 mm × 1.2 mm (L × W × H), optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC320A-I/ST, the 25AA320A-I/ST offers broader voltage flexibility (1.8V start) for battery-powered designs, while AT25DF321A-MAU-T provides higher density and speed at the cost of interface compatibility and pin-level replaceability - making 25AA320A-I/ST optimal for cost-sensitive, low-power, SPI-constrained embedded systems.

Availability

25AA320A-I/ST is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, medical handheld diagnostics, and smart energy metering requiring stable component supply across extended product lifecycles.

Supply support for 25AA320A-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 microcontrollers, analog devices, and memory solutions, serving industrial, automotive, and consumer markets with vertically integrated silicon and development tools.

The 25AA320A belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-voltage, SPI-based nonvolatile data storage in resource-constrained embedded systems where simplicity, longevity, and qualification assurance are critical.

FAQ

What is the minimum supply voltage required for reliable operation of the 25AA320A-I/ST?

The 25AA320A-I/ST operates reliably down to 1.8V across its full industrial temperature range (–40°C to +85°C), with AC timing parameters adjusted accordingly (e.g., max clock drops to 3 MHz below 2.5V). This enables direct integration into 1.8V and 2.5V microcontroller domains without level-shifting circuitry. The 25AA320A-I/ST maintains full functionality including page write, STATUS register access, and HOLD operation at 1.8V.

How does the HOLD pin function during an active SPI transaction on the 25AA320A-I/ST?

The HOLD pin on the 25AA320A-I/ST suspends serial communication mid-transaction when pulled low while SCK is low, placing SO in high-impedance state immediately. SI and SCK transitions are ignored during hold, preserving the internal address pointer and instruction state. Resuming requires bringing HOLD high while SCK remains low; the 25AA320A-I/ST then continues from the exact point of suspension without retransmission.

Can the 25AA320A-I/ST be used as a direct replacement for the 25LC320A-I/ST in existing designs?

The 25AA320A-I/ST is pin- and software-compatible with the 25LC320A-I/ST, differing only in minimum VCC (1.8V vs. 2.5V). In systems operating ≥2.5V, the 25AA320A-I/ST functions identically and may be substituted without layout or firmware changes. However, if the design relies on 25LC320A's tighter 2.5–5.5V spec for margin or qualification, verify 25AA320A-I/ST behavior at 2.5V under worst-case timing and temperature.

What memory protection mechanisms are implemented in the 25AA320A-I/ST?

The 25AA320A-I/ST implements three layered protections: (1) Write-enable latch (WEL) reset on power-up and after each write, (2) Software-configurable block protection (BP0/BP1 bits) locking 0%, 25%, 50%, or 100% of memory, and (3) Hardware write-protection via WP pin when WPEN bit is set. These operate independently - e.g., WP can lock STATUS register writes while allowing array writes if BP bits permit.

Is the 25AA320A-I/ST qualified for automotive applications?

The 25AA320A-I/ST is AEC-Q100 qualified for automotive applications, meeting stress test requirements for temperature cycling, HTOL, and ESD. Its industrial temperature grade (–40°C to +85°C) aligns with passenger compartment and body electronics use cases. While not rated for engine bay (Grade 0 or 1), it is approved for dashboard controllers, door modules, and lighting ECUs where ambient conditions remain within its specified range.