Microchip Technology 25C320-I/P

Overview

25C320-I/P from Microchip Technology Inc. is a 32 Kbit SPI serial EEPROM IC designed for nonvolatile data storage in embedded systems. It features 4096 × 8-bit organization, 3 MHz max clock frequency at 4.5–5.5 V, 5 ms max write cycle time, and industrial temperature range (−40°C to +85°C) in 8-pin PDIP package. It supports block write protection, HOLD pin for interrupt-safe pausing, and hardware write protection via WP pin.

For engineers reviewing the 25C320-I/P datasheet, 25C320-I/P pinout, 25C320-I/P application, or 25C320-I/P equivalent, key selection criteria include its 5V-only operation, 3 MHz SPI interface speed, 8-pin PDIP mechanical compatibility, and hardware-based write protection architecture with STATUS register control.

Technical Context

The 25C320-I/P implements a standard SPI Mode 0,0 (CPOL=0, CPHA=0) interface with separate SI (data-in) and SO (data-out) lines, requiring CS, SCK, SI, SO, HOLD, and WP control signals. Its internal architecture includes an 8-bit instruction register, page-based write buffer (32-byte pages), and STATUS register with WIP, WEL, BP0/BP1, and WPEN bits.

Write operations require explicit WREN instruction followed by CS high-to-low transition to initiate self-timed internal erase-and-write cycles. The HOLD pin suspends ongoing serial transfers without resetting the address pointer, enabling deterministic interrupt handling in real-time microcontroller systems.

Key Specifications

Pinout & Package

8-pin Plastic DIP (300 mil body), through-hole mount, RoHS-compliant matte tin finish. Pin 1 marked with notch or dot; pin count and spacing conform to JEDEC MS-001.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 25C320-I/P, 25AA320-I/P offers broader supply flexibility but lower speed, while 25LC320-I/P provides better automotive qualification and ESD robustness at intermediate voltage and speed - all share identical pinout, instruction set, and memory map.

Availability

25C320-I/P 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 25C320-I/P 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, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 25C320 belongs to Microchip's legacy 5V SPI EEPROM product line, engineered for cost-sensitive, high-reliability industrial and automotive applications requiring proven nonvolatile storage with hardware write protection.

FAQ

What is the operating voltage range of the 25C320-I/P?

The 25C320-I/P operates strictly within 4.5 V to 5.5 V. It is not rated for 3.3 V or lower supply voltages. Attempting to power it below 4.5 V may result in unreliable read/write behavior or failure to enter standby mode. This fixed 5V requirement simplifies integration in legacy 5V systems but precludes direct use with modern 3.3V microcontrollers without level translation.

Does the 25C320-I/P support SPI Mode 3,0 (CPOL=1, CPHA=0)?

No, the 25C320-I/P supports only SPI Mode 0,0 (CPOL=0, CPHA=0). Its serial interface requires clock polarity low and sampling on the rising edge of SCK. Using Mode 3,0 will cause misaligned bit sampling and communication failure. The device does not auto-detect or adapt to alternate SPI modes - correct mode configuration in the host MCU's SPI peripheral is mandatory for reliable operation of the 25C320-I/P.

How does the HOLD pin function during an active write cycle?

The HOLD pin has no effect once an internal write cycle has started in the 25C320-I/P. It can only pause ongoing read or write command sequences before the CS high-to-low transition that initiates the internal write. During active write (WIP=1), the HOLD signal is ignored - the device completes the 5 ms self-timed operation regardless of HOLD state. This ensures data integrity even if host interrupts occur mid-write.

Can the 25C320-I/P be used in automotive under-hood applications?

No, the 25C320-I/P is rated only for Industrial temperature range (−40°C to +85°C), not Automotive (−40°C to +125°C). Its datasheet specifies no characterization or qualification for operation above +85°C. For under-hood applications such as engine control or transmission modules, Microchip recommends the 25C320-E/P variant or the 25LC320-E/P, both explicitly qualified to +125°C and tested for automotive reliability standards.

What happens to the write enable latch after issuing a WRITE instruction?

After a successful WRITE instruction completes in the 25C320-I/P, the write enable latch (WEL) is automatically reset to '0'. This means the next write operation requires re-execution of the WREN instruction before sending another WRITE command. This safety mechanism prevents accidental multiple writes due to software errors or noise on the SPI bus, ensuring each write is an explicit, two-step process: WREN → WRITE.