Microchip Technology AT25256AW-10SI-2.7-T

Overview

AT25256AW-10SI-2.7-T from Microchip Technology (formerly Atmel) is a 256 Kbit SPI serial EEPROM organized as 32,768 × 8 bits, operating from 2.7V to 5.5V, featuring 20 MHz max clock rate at 5V, 64-byte page write capability, and hardware/software write protection via WP and HOLD pins. It is used in industrial control modules for nonvolatile parameter storage requiring automotive-grade reliability.

For engineers reviewing the AT25256AW-10SI-2.7-T datasheet, AT25256AW-10SI-2.7-T pinout, AT25256AW-10SI-2.7-T application, or AT25256AW-10SI-2.7-T equivalent, this page delivers verified electrical specs, JEDEC SOIC-8 package details, SPI Mode 0/3 timing compliance, block protection configuration, and real-world design implications for embedded firmware update and calibration data retention.

Technical Context

The AT25256AW-10SI-2.7-T implements a synchronous SPI slave interface with separate SI (input) and SO (output) pins, supporting MSB-first transmission and op-code–driven command execution (e.g., WREN, WRITE, RDSR). It uses an internal 8-bit instruction register and requires CS low to initiate communication.

Its architecture includes a nonvolatile status register with BP0/BP1 bits enabling 1/4, 1/2, or full-array block write protection, and a WPEN bit controlling hardware write protection activation via the WP pin. The HOLD pin suspends ongoing serial transfers without resetting sequence state, preserving address continuity during master arbitration.

Key Specifications

Pinout & Package

AT25256AW-10SI-2.7-T is housed in an 8-lead JEDEC-standard SOIC package (8S1), 0.150" body width, with gull-wing leads and RoHS-compliant matte tin plating. Pin 1 is marked by a beveled corner or dot; the package meets IPC/JEDEC MS-012AA mechanical specifications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95256-DRMN6TP/K and BR25H256FJ-WE2, the AT25256AW-10SI-2.7-T uniquely combines guaranteed 2.7V operation, HOLD pin support, and automotive-qualified JEDEC SOIC packaging - making it optimal for resource-constrained industrial hosts needing robust, interruptible EEPROM access.

Availability

AT25256AW-10SI-2.7-T is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostic instruments, automotive body control modules, and smart energy metering systems requiring stable component supply across long production lifecycles.

Supply support for AT25256AW-10SI-2.7-T 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 acquired Atmel in 2016 and maintains full technical support, documentation, and manufacturing continuity for the AT25xxx family of SPI EEPROMs.

The AT25256AW-10SI-2.7-T belongs to Microchip's serial EEPROM product line, designed specifically for reliable, low-power nonvolatile storage in space-constrained embedded systems where SPI interface simplicity and data integrity are critical.

FAQ

What is the maximum clock frequency supported by the AT25256AW-10SI-2.7-T at 3.3V operation?

The AT25256AW-10SI-2.7-T supports up to 10 MHz SCK frequency when VCC = 2.7–3.6V, per its AC Characteristics table. This is confirmed in the datasheet's fSCK specification row for 2.7–5.5V voltage range, where max frequency is 10 MHz. At 5V, the part achieves 20 MHz. The AT25256AW-10SI-2.7-T must not exceed 10 MHz in 3.3V systems to meet setup/hold timing margins.

Does the AT25256AW-10SI-2.7-T require an external pull-up resistor on the SO pin?

No, the AT25256AW-10SI-2.7-T features an actively driven SO output that transitions between VOL and VOH states without requiring external pull-ups. Its SO pin is designed for direct connection to standard CMOS inputs; adding a pull-up may cause contention during low-level drive and violate VOL specifications. The AT25256AW-10SI-2.7-T datasheet specifies VOH min and VOL max under defined load conditions, confirming active push-pull behavior.

How does the HOLD pin function during an ongoing WRITE cycle of the AT25256AW-10SI-2.7-T?

The HOLD pin has no effect during an internal WRITE cycle (tWC = 5 ms); once initiated, the AT25256AW-10SI-2.7-T ignores HOLD assertions and continues programming. HOLD only suspends serial communication during active read/write transactions *before* CS goes high. During tWC, only RDSR is accepted - the AT25256AW-10SI-2.7-T remains unresponsive to HOLD until the write completes and returns to standby.

Can the AT25256AW-10SI-2.7-T be used in SPI Mode 1 (CPOL=0, CPHA=1)?

No, the AT25256AW-10SI-2.7-T explicitly supports only SPI Modes 0 (CPOL=0, CPHA=0) and 3 (CPOL=1, CPHA=1), as stated in its Features section. Attempting Mode 1 will result in misaligned sampling of SI/SO relative to SCK edges, causing command corruption or read failures. The AT25256AW-10SI-2.7-T's timing diagrams and functional description confirm data is latched on SCK rising edge (Mode 0) or falling edge (Mode 3), not the opposite phase.

What happens if the WP pin is held low while the WPEN bit is '0' in the AT25256AW-10SI-2.7-T status register?

When WPEN = 0, the WP pin is disabled regardless of its logic level - the AT25256AW-10SI-2.7-T allows full write access to the status register and unprotected memory. This configuration enables safe initial programming in systems where WP is hardwired to GND. The AT25256AW-10SI-2.7-T datasheet Table 5 confirms WPEN=0 overrides WP state, permitting writes even with WP low, provided WREN is executed first.