Microchip Technology 25AA320X-I/ST

Overview

25AA320X-I/ST from Microchip Technology Inc. is a 32 Kbit (4096 × 8) SPI-compatible serial EEPROM with 1.8–5.5 V supply range, 1 MHz max clock frequency, 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 embedded systems for storing configuration data, calibration parameters, and firmware patches where low-power nonvolatile memory is required.

For engineers reviewing the 25AA320X-I/ST datasheet, 25AA320X-I/ST pinout, 25AA320X-I/ST application, or 25AA320X-I/ST equivalent, key selection considerations include its 1.8 V minimum V_CC, 500 nA typical standby current, HOLD pin support for interrupt-safe SPI pausing, and TSSOP-8 package with alternate pinout (CS/SO/WP/V_SS/SI/SCK/HOLD/V_CC).

Technical Context

The 25AA320X-I/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 power pins. Its internal architecture includes an 8-bit instruction register, auto-incrementing address pointer for sequential reads, and a STATUS register with WIP, WEL, BP0/BP1, and WPEN bits for configurable block protection.

Write operations require explicit WREN instruction followed by WRITE command and address/data; writes are self-timed and complete in ≤5 ms. The device supports page writes up to 32 bytes within the same 32-byte boundary and provides hardware-level data integrity via power-on reset of the write enable latch, built-in write-protection circuitry, and 1 million endurance cycles.

Key Specifications

Pinout & Package

25AA320X-I/ST is housed in an 8-pin Plastic Thin Shrink Small Outline Package (TSSOP-8) with 4.4 mm body width and alternate pinout per Microchip's part numbering convention ('X' suffix). Pin 1 is CS; pin 2 is SO; pin 3 is WP; pin 4 is V_SS; pin 5 is SI; pin 6 is SCK; pin 7 is HOLD; pin 8 is V_CC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25AA320X-I/ST, the 25AA320A-I/ST offers improved ESD tolerance while maintaining full electrical and mechanical compatibility, whereas AT25DF321A-SSH-T introduces architectural differences (flash vs. EEPROM, quad-SPI vs. standard SPI) that necessitate firmware and layout changes.

Availability

25AA320X-I/ST is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, smart energy meter firmware patch storage, and automotive body control module settings requiring stable component supply and long-term obsolescence management.

Supply support for 25AA320X-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, analog, and Flash-IP solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25AA320X-I/ST belongs to Microchip's 25XX320 family of SPI serial EEPROMs, designed specifically for low-voltage, low-power embedded systems requiring reliable, byte-addressable nonvolatile storage with simple interface overhead.

FAQ

What is the supply voltage range supported by the 25AA320X-I/ST?

The 25AA320X-I/ST operates from 1.8 V to 5.5 V, making it compatible with 1.8 V, 2.5 V, 3.3 V, and 5 V logic systems. This wide V_CC range eliminates the need for external level shifters when interfacing with mixed-voltage microcontrollers. The device maintains full AC and DC specifications across this entire range, including 1 MHz max clock at 1.8 V.

Does the 25AA320X-I/ST support page writes, and what is the maximum page size?

Yes, the 25AA320X-I/ST supports page writes with a fixed 32-byte page size. Up to 32 bytes can be loaded into the write buffer in a single transaction, provided all addresses fall within the same page boundary (e.g., 0x0000–0x001F). Exceeding the page boundary causes wraparound and unintended overwrites - a constraint explicitly defined in the 25AA320X-I/ST datasheet.

How does the HOLD pin function in the 25AA320X-I/ST, and what are its timing requirements?

The HOLD pin in the 25AA320X-I/ST suspends ongoing SPI communication without resetting the internal state. To activate HOLD, the pin must be driven low while SCK is low; to resume, it must be raised high while SCK remains low. During HOLD, SI, SCK, and SO enter high-impedance, allowing the host MCU to service higher-priority interrupts safely - a feature confirmed in DS21227F Figure 1-1 and Section 2.6.

What write protection mechanisms are implemented in the 25AA320X-I/ST?

The 25AA320X-I/ST implements three-tiered write protection: (1) software-controlled block protection via BP0/BP1 bits in the STATUS register, (2) hardware write-enable latch (WEL) reset on power-up or WRDI, and (3) pin-based protection using the WP pin enabled by the WPEN bit. These mechanisms are fully documented in Sections 2.3, 3.6, and Table 3-3 of the 25AA320X-I/ST datasheet.

Is the 25AA320X-I/ST pin-compatible with other variants like 25LC320X-I/ST or 25C320X-I/ST?

No - while all share the same TSSOP-8 'X' pinout (CS/SO/WP/V_SS/SI/SCK/HOLD/V_CC), the 25AA320X-I/ST is not electrically interchangeable with 25LC320X-I/ST or 25C320X-I/ST due to differing V_CC ranges (1.8–5.5 V vs. 2.5–5.5 V vs. 4.5–5.5 V) and max clock frequencies (1 MHz vs. 2 MHz vs. 3 MHz). These differences affect system-level timing and power rail design.