Microchip Technology 25AA320-I/SN

Overview

25AA320-I/SN from Microchip Technology Inc. is a 32 Kbit SPI serial EEPROM with 4096 × 8-bit organization, 1.8–5.5 V supply range, and industrial temperature rating (–40°C to +85°C). It features 32-byte page write capability, 5 ms max internal write cycle time, and hardware write protection via WP pin and STATUS register. It is used in microcontroller-based systems for nonvolatile parameter storage, calibration data retention, and firmware configuration.

For engineers reviewing the 25AA320-I/SN datasheet, 25AA320-I/SN pinout, 25AA320-I/SN application, or 25AA320-I/SN equivalent, key selection criteria include SPI interface compatibility, low-voltage operation down to 1.8 V, block write protection granularity (none/¼/½/all), endurance of 1 million write/erase cycles, and SOIC-8 packaging for space-constrained PCB layouts.

Technical Context

The 25AA320-I/SN implements a standard SPI Mode 0,0 (CPOL = 0, CPHA = 0) interface with separate SI and SO lines, CS-controlled device selection, and HOLD pin for transaction suspension without reset. Its internal architecture includes an 8-bit instruction register, auto-incrementing address pointer for sequential reads, and a nonvolatile STATUS register with WIP, WEL, BP0/BP1, and WPEN bits.

Write operations require explicit WREN instruction before WRITE or WRSR commands; the write enable latch resets after power-up, WRDI, WRSR, or successful WRITE. Block protection is configurable via BP0/BP1 bits to lock none, upper 1/4 (0C00h–0FFFh), upper 1/2 (0800h–0FFFh), or full array (0000h–0FFFh).

Key Specifications

Pinout & Package

25AA320-I/SN is housed in an 8-pin plastic SOIC package (150 mil body width), compliant with JEDEC MS-012, with lead finish Matte Tin (Pb-free). Pin 1 is marked by a beveled corner or dot; pin numbering follows standard SOIC convention.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA320-I/SN, the 25AA320A-I/SN offers identical functionality with improved manufacturing process and lifecycle support, while AT25DF321A-SHN-T provides greater density and speed at the cost of architectural compatibility and simplified protection scheme.

Availability

25AA320-I/SN is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, and automotive body control modules requiring stable component supply and long-term obsolescence management.

Supply support for 25AA320-I/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, manufacturing, and sales operations.

The 25AA320-I/SN belongs to Microchip's legacy SPI Serial EEPROM product line, designed specifically for low-voltage, high-reliability nonvolatile data storage in resource-constrained embedded systems.

FAQ

What is the maximum clock frequency supported by the 25AA320-I/SN?

The 25AA320-I/SN supports a maximum SPI clock frequency of 1 MHz when operating across its full 1.8–5.5 V supply range. This limit is specified under industrial temperature conditions (–40°C to +85°C) and ensures reliable setup/hold timing for SI and SO signals. At higher supply voltages (≥4.5 V), the device can sustain this rate without derating; no overclocking beyond 1 MHz is guaranteed or characterized.

Does the 25AA320-I/SN support SPI Mode 1,1 or only Mode 0,0?

The 25AA320-I/SN supports only SPI Mode 0,0 (CPOL = 0, CPHA = 0), where data is sampled on the rising edge of SCK and shifted out on the falling edge. The datasheet explicitly defines timing relative to this mode, and no alternate modes are implemented. Attempting Mode 1,1 will result in incorrect data capture or communication failure due to mismatched sampling edges.

How does the HOLD pin function during an active write cycle in the 25AA320-I/SN?

The HOLD pin has no effect on an internal write cycle already in progress in the 25AA320-I/SN. Once CS is raised to initiate the self-timed 5 ms write, the device ignores HOLD transitions until the cycle completes. HOLD only suspends serial communication (instruction/address/data transfer), not ongoing EEPROM programming. The WIP bit remains set during this time and must be polled to confirm completion.

Can the 25AA320-I/SN be used with a 1.8 V microcontroller SPI interface?

Yes, the 25AA320-I/SN is fully compatible with 1.8 V microcontrollers: its VCC range is 1.8–5.5 V, VIH1 threshold is 2.0 V (min) at VCC ≥ 2.7 V and 0.7×VCC (min) at lower VCC, and VOL is guaranteed ≤ 0.2 V at IOL = 1.0 mA. When powered at 1.8 V, it meets all DC and AC timing specs, including 1 MHz clock operation and proper logic-level recognition.

What happens to the write enable latch after a successful WRITE command in the 25AA320-I/SN?

After a successful WRITE command completes in the 25AA320-I/SN, the write enable latch is automatically reset. This means that any subsequent write attempt-whether byte, page, or STATUS register-requires reissuing the WREN instruction before CS is lowered. This behavior prevents accidental writes and enforces explicit enablement per operation, enhancing data integrity in interrupt-driven or multi-threaded firmware environments.