Microchip Technology AT25256-10PI-1.8

Overview

AT25256-10PI-1.8 from Microchip Technology (formerly Atmel) is a 256 Kbit serial SPI EEPROM organized as 32,768 × 8-bit memory array, operating from 1.8 V to 5.5 V supply, supporting 3 MHz clock rate, 64-byte page write, and hardware/software write protection via WP and HOLD pins. It is used in industrial control modules for nonvolatile parameter storage under low-power conditions.

For engineers reviewing the AT25256-10PI-1.8 datasheet, AT25256-10PI-1.8 pinout, AT25256-10PI-1.8 application, or AT25256-10PI-1.8 equivalent, key selection criteria include 1.8V operation compatibility, SOIC-8 package footprint, SPI Mode 0/3 support, block write protection granularity (1/4, 1/2, full array), and automotive-grade temperature range (–40°C to +85°C).

Technical Context

The AT25256-10PI-1.8 implements a synchronous serial peripheral interface (SPI) slave architecture with separate SI/SO lines, MSB-first data transfer, and chip-select–driven command sequencing. It uses an 8-bit instruction register with op-codes for WREN, WRITE, READ, RDSR, and WRSR.

Internal self-timed write cycles (5 ms typical) eliminate external timing control; block protection is configured via nonvolatile BP0/BP1 bits in the status register, while WPEN enables/disables hardware write protection through the WP pin. HOLD suspends ongoing serial transfers without resetting the sequence.

Key Specifications

Pinout & Package

AT25256-10PI-1.8 is housed in an 8-lead JEDEC SOIC package (8S1), 0.150" wide body, surface-mount compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25256-10PI-1.8, M95256-WMN6TP trades HOLD functionality for higher speed, while BR25L256FJ-WE2 extends temperature capability and retains all control pins - both require validation of status register bit mapping and write-enable behavior before drop-in replacement.

Availability

AT25256-10PI-1.8 is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, smart energy metering, and medical diagnostic equipment requiring stable component supply and long-term obsolescence management.

Supply support for AT25256-10PI-1.8 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 is a global semiconductor company specializing in microcontrollers, analog devices, and memory solutions, with strong heritage in legacy Atmel products including serial EEPROMs.

The AT25256 series was designed for cost-sensitive, low-power embedded systems needing reliable nonvolatile storage with minimal external components - particularly targeting industrial, automotive, and consumer applications where SPI interface simplicity and voltage flexibility are critical.

FAQ

What is the maximum clock frequency supported by AT25256-10PI-1.8?

The AT25256-10PI-1.8 supports up to 3 MHz SCK frequency across its full 1.8 V to 5.5 V supply range, as specified in Table 4 of the datasheet. This value is guaranteed for operation from –40°C to +85°C and applies to both read and write commands. Exceeding 3 MHz may result in timing violations and data corruption, especially at lower VCC levels.

Does AT25256-10PI-1.8 support SPI Mode 1 or Mode 2?

No, AT25256-10PI-1.8 explicitly supports only SPI Modes 0 (CPOL = 0, CPHA = 0) and 3 (CPOL = 1, CPHA = 1), as stated in the Features section. It does not support Mode 1 or Mode 2 due to fixed sampling and setup timing relative to SCK edges. Attempting Mode 1 or 2 will cause misaligned data capture and failed communications.

How is block write protection configured on AT25256-10PI-1.8?

Block write protection on AT25256-10PI-1.8 is configured by writing to the status register using the WRSR instruction. Bits BP1 and BP0 determine protected regions: 00 = none, 01 = top 1/4 (6000–7FFFh), 10 = top 1/2 (4000–7FFFh), 11 = full array (0000–7FFFh). These bits are nonvolatile and retain settings after power cycle.

Is AT25256-10PI-1.8 pin-compatible with AT25256-10PI-2.7?

Yes, AT25256-10PI-1.8 and AT25256-10PI-2.7 share identical 8-lead SOIC (8S1) packaging, pinout, and mechanical dimensions. The only functional difference is the minimum operating voltage: 1.8 V vs. 2.7 V. Both parts use the same instruction set, timing, and register map, enabling direct substitution in 2.7V+ systems - though 1.8V operation is disabled in the -2.7 variant.

What happens if the WP pin is held low during power-up of AT25256-10PI-1.8?

If WP is low at power-up and the WPEN bit is set to "1", hardware write protection activates immediately, preventing writes to the status register and any block-protected memory regions. If WPEN = "0", the WP pin has no effect regardless of its state. WP status is evaluated dynamically during each write attempt, not latched at startup.