Microchip Technology AT25256AN-10SI-1.8-T

Overview

AT25256AN-10SI-1.8-T from Microchip Technology (formerly Atmel) is a 256 Kbit SPI serial EEPROM organized as 32,768 × 8 bits, operating from 1.8 V to 5.5 V, supporting 5 MHz clock rate at 1.8 V, featuring hardware write protection via WP pin and HOLD suspend functionality, and housed in an 8-lead JEDEC SOIC package for industrial temperature range (−40°C to +85°C).

For engineers reviewing the AT25256AN-10SI-1.8-T datasheet, AT25256AN-10SI-1.8-T pinout, AT25256AN-10SI-1.8-T application, or AT25256AN-10SI-1.8-T equivalent, this page delivers verified electrical specs, validated pin functions, confirmed low-voltage timing behavior, and real-world use cases in automotive control modules, industrial sensor nodes, and embedded configuration storage where 1.8 V compatibility and block-level write protection are required.

Technical Context

The AT25256AN-10SI-1.8-T implements a synchronous SPI slave interface compliant with Modes 0 (CPOL=0, CPHA=0) and 3 (CPOL=1, CPHA=1), with separate SI (input) and SO (output) pins enabling full-duplex-capable half-duplex operation. It uses an 8-bit instruction register with MSB-first data transfer and requires WREN before WRITE or WRSR commands.

Internal architecture includes a nonvolatile status register (WPEN, BP1/BP0, WEN, RDY) controlling block write protection across four memory segments (0–7FFFh), hardware/software write enable/disable, and READY/BUSY flag reporting. All write cycles are self-timed (≤5 ms max), with no external erase needed and automatic return to write-disable state post-write.

Key Specifications

Pinout & Package

AT25256AN-10SI-1.8-T is packaged in an 8-lead JEDEC SOIC (8S1), 0.150" wide body, surface-mount package with standard gull-wing leads and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95256-DW MN6TP and BR25V256FJ-WE2, the AT25256AN-10SI-1.8-T offers native HOLD support and Atmel/Microchip's long-standing automotive qualification pedigree, making it preferable for safety-critical suspend/resume operations and legacy design continuity-though BR25V256FJ-WE2 provides superior 1.8 V speed and lower standby current where HOLD is nonessential.

Availability

AT25256AN-10SI-1.8-T is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor nodes, and medical handheld diagnostics requiring stable component supply across extended product lifecycles.

Supply support for AT25256AN-10SI-1.8-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 and manufacturing continuity for the AT25xxx family of SPI EEPROMs.

The AT25256AN-10SI-1.8-T belongs to Microchip's serial EEPROM product line, designed specifically for robust, low-voltage, nonvolatile data storage in resource-constrained embedded systems where reliability, small footprint, and SPI simplicity are paramount.

FAQ

What is the maximum clock frequency supported by AT25256AN-10SI-1.8-T at 1.8 V?

The AT25256AN-10SI-1.8-T supports up to 5 MHz SCK frequency when operated at 1.8 V, as specified in the AC Characteristics table under "1.8–5.5 V" voltage column. This ensures compatibility with low-power microcontrollers running from 1.8 V rails without requiring clock dividers or timing margin compromises. The AT25256AN-10SI-1.8-T maintains full read/write functionality at this rate across its full industrial temperature range.

Does AT25256AN-10SI-1.8-T support hardware write protection independent of software commands?

Yes, AT25256AN-10SI-1.8-T supports independent hardware write protection via the WP pin. When WP is driven low and the WPEN bit in the status register is set to "1", writes to the status register and block-protected memory regions are disabled-even if WREN has been issued. This protection persists across power cycles and does not require active firmware intervention, making AT25256AN-10SI-1.8-T suitable for safety-critical storage where accidental overwrites must be physically prevented.

Can AT25256AN-10SI-1.8-T be used in place of AT25256AN-10SI-2.7-T?

AT25256AN-10SI-1.8-T and AT25256AN-10SI-2.7-T share identical pinout, package, and memory organization but differ in minimum supply voltage: the -1.8-T version operates down to 1.8 V, while the -2.7-T requires ≥2.7 V. Substitution is safe only if the target system's VCC remains ≥2.7 V; using the -1.8-T in a 2.7 V system introduces no risk, but the reverse risks functional failure. Both versions maintain identical timing and endurance specs above their respective VCC minima.

What memory addressing scheme does AT25256AN-10SI-1.8-T use for READ and WRITE operations?

AT25256AN-10SI-1.8-T uses a 15-bit address space (A14–A0) to access its 32,768 bytes, transmitted MSB-first after the READ or WRITE op-code. Address bits A14–A0 are sent sequentially on SI; the internal address counter auto-increments during multi-byte reads/writes. For PAGE WRITE, only the lower 6 bits roll over, limiting burst writes to 64 bytes per CS assertion-ensuring AT25256AN-10SI-1.8-T avoids unintended wraparound in configuration block updates.

How does the HOLD pin function during an active SPI transaction on AT25256AN-10SI-1.8-T?

During an active SPI transaction, asserting HOLD low (while SCK is low) suspends communication without resetting the internal address or instruction state; SO enters high-impedance and SI inputs are ignored. Resuming requires bringing HOLD high while SCK remains low-then normal clocking resumes from the exact bit position where it paused. This behavior allows AT25256AN-10SI-1.8-T to coexist with time-sensitive peripherals in interrupt-driven systems without data loss or reinitialization overhead.