Microchip Technology 25AA320AT-I/MS

Overview

25AA320AT-I/MS from Microchip Technology 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 at 4.5–5.5V, and delivers 5 µA standby current. It is used for nonvolatile parameter storage in microcontroller-based embedded systems requiring AEC-Q100-qualified memory.

For engineers reviewing the 25AA320AT-I/MS datasheet, 25AA320AT-I/MS pinout, 25AA320AT-I/MS application, or 25AA320AT-I/MS equivalent, key selection criteria include SPI interface compatibility, write-protection flexibility (BP0/BP1), HOLD functionality for interrupt-safe operation, and MSOP-8 packaging for space-constrained PCB layouts.

Technical Context

The 25AA320AT-I/MS implements a standard SPI Mode 0,0 or Mode 1,1 interface with separate SI (data in) and SO (data out) lines, controlled by CS, SCK, and optional HOLD/WP pins. Its internal architecture includes an 8-bit instruction register, page latches, and high-voltage generation circuitry for EEPROM programming.

It supports byte and page write operations (up to 32 bytes within one 32-byte page boundary), self-timed internal write cycles (≤5 ms), and real-time STATUS register polling (WIP, WEL, BP0/BP1, WPEN) during active writes - enabling deterministic firmware control without blocking host CPU execution.

Key Specifications

Pinout & Package

25AA320AT-I/MS is housed in an 8-lead MSOP (Mini Small Outline Package) with 150-mil body width, gull-wing leads, and exposed pad (optional VSS connection per Microchip drawing C04-2057-SN Rev F).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25LC320AT-I/MS, the 25AA320AT-I/MS supports wider VCC (1.8V–5.5V) for ultra-low-power designs, while AT25DF321A-MAU-T offers vastly greater density but demands architectural changes - making 25AA320AT-I/MS optimal for cost-sensitive, space-constrained parameter storage where voltage flexibility and proven SPI simplicity are essential.

Availability

25AA320AT-I/MS is available at Aetrix Electronics and suitable for automotive body control modules, industrial PLC configuration storage, medical infusion pump calibration, and smart energy meter firmware parameters requiring stable component supply and long-term lifecycle assurance.

Supply support for 25AA320AT-I/MS 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, and Flash-IP solutions, serving automotive, industrial, consumer, and communications markets with vertically integrated silicon and development tools.

The 25AA320A family was designed specifically for robust, low-power serial parameter storage in microcontroller-based systems - emphasizing SPI simplicity, hardware write protection, and extended data retention for mission-critical embedded applications.

FAQ

What is the maximum clock frequency supported by the 25AA320AT-I/MS?

The 25AA320AT-I/MS supports up to 10 MHz clock frequency when VCC is between 4.5V and 5.5V. At 2.5V ≤ VCC < 4.5V, the maximum is 5 MHz; below 2.5V (down to 1.8V), it is limited to 3 MHz. These limits are defined in Table 1-2 AC Characteristics and ensure reliable setup/hold timing across voltage and temperature ranges. The 25AA320AT-I/MS must be operated within these bounds to guarantee correct SPI communication and avoid data corruption.

Does the 25AA320AT-I/MS require external components for basic operation?

Yes - the 25AA320AT-I/MS requires a 0.1 µF ceramic decoupling capacitor placed as close as possible to the VCC and VSS pins to suppress supply noise during internal write cycles. No pull-up resistors are needed on SI, SO, or SCK, as the device uses CMOS-compatible inputs and open-drain SO. However, CS, WP, and HOLD should be actively driven (not left floating); weak pull-ups may be used on WP if hardware protection is disabled via WPEN=0.

How does the HOLD pin function during an ongoing SPI read sequence?

When HOLD is pulled low while SCK is low during an active SPI read, the 25AA320AT-I/MS immediately places SO in high-impedance state and ignores further SI/SCK transitions. The internal address pointer and shift register state are preserved. Upon returning HOLD to high (while SCK remains low), SO resumes outputting the next byte on the subsequent SCK falling edge - continuing the exact same read sequence without restart. This behavior is confirmed in Section 2.6 and Figure 1-1 of DS20001828H.

Can the 25AA320AT-I/MS be used in automotive applications?

Yes - the 25AA320AT-I/MS belongs to the AEC-Q100-qualified 25AA320A/25LC320A family and is rated for Industrial temperature range (–40°C to +85°C), which satisfies many automotive cabin and engine bay peripheral requirements. While the "I" suffix denotes Industrial grade, its qualification evidence and robustness (e.g., >4 kV ESD, >1M endurance) make it suitable for non-safety-critical automotive subsystems like body control, lighting, and HVAC when validated per end-system requirements.

What happens if a page write crosses a 32-byte boundary on the 25AA320AT-I/MS?

If a page write command attempts to write across a 32-byte physical page boundary (e.g., starting at address 0x001F and writing 4 bytes), the 25AA320AT-I/MS wraps the excess data back to the start of the same page (address 0x0000), overwriting previously written bytes. This behavior is explicitly documented in Figure 3-3 notes and Section 3.3. Firmware must enforce page alignment - calculating (address & 0xFFE0) to determine page base - before initiating multi-byte writes to prevent unintended data loss.