Microchip Technology AT25256A-10TI-1.8

Overview

AT25256A-10TI-1.8 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 TSSOP package for space-constrained industrial control and sensor node applications.

For engineers reviewing the AT25256A-10TI-1.8 datasheet, AT25256A-10TI-1.8 pinout, AT25256A-10TI-1.8 application, or AT25256A-10TI-1.8 equivalent, this page delivers verified electrical parameters, validated SOIC/TSSOP pin mapping, confirmed 1.8 V low-voltage operation limits, and real-world use cases in automotive body electronics and IoT edge devices requiring >100-year data retention and 100,000 write cycles.

Technical Context

The AT25256A-10TI-1.8 implements a synchronous SPI slave interface with separate SI/SO lines, supports SPI modes 0 and 3, and uses MSB-first transmission with op-code–driven command execution (WREN, WRITE, RDSR, WRSR). It features a nonvolatile status register with BP0/BP1 for 1/4-, 1/2-, or full-array block write protection and WPEN bit enabling hardware write protect via the WP pin.

Internal self-timed write cycles complete in ≤5 ms; no external erase step is required. The HOLD pin suspends ongoing serial communication without resetting the sequence when asserted low during SCK low time, preserving address and state integrity across master-initiated pauses.

Key Specifications

Pinout & Package

AT25256A-10TI-1.8 is packaged in an 8-lead Thin Shrink Small Outline Package (TSSOP), 0.170" wide, with 0.65 mm lead pitch, JEDEC MO-153 compliant, optimized for automated PCB assembly and thermal performance in compact layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25256A-10TI-1.8, M95256-DWDW3TP/K offers faster 5 V operation but omits HOLD-limiting real-time system responsiveness-while BR25H256FJ-WE2 adds ECC and lower voltage headroom at the cost of higher unit price and no HOLD pin; AT25256A-10TI-1.8 remains optimal for cost-sensitive industrial designs needing suspend and proven 100K-cycle endurance.

Availability

AT25256A-10TI-1.8 is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and smart metering applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for AT25256A-10TI-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 acquired Atmel in 2016 and maintains full product continuity, quality assurance, and technical documentation for the AT25xxx family of serial EEPROMs.

The AT25256A-10TI-1.8 belongs to Microchip's legacy SPI EEPROM product line, engineered for robust nonvolatile data storage in resource-constrained embedded systems where low-voltage operation, hardware write security, and extended temperature reliability are mandatory.

FAQ

What is the maximum clock frequency supported by AT25256A-10TI-1.8 at 1.8 V?

The AT25256A-10TI-1.8 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 limit ensures reliable setup/hold timing margins for SI sampling and SO valid output, especially critical in low-voltage noise-sensitive environments like battery-powered IoT nodes. Exceeding 5 MHz at 1.8 V may cause read/write failures due to insufficient internal timing margin.

Does AT25256A-10TI-1.8 support SPI Mode 1 or Mode 2?

No, AT25256A-10TI-1.8 supports only SPI Modes 0 (CPOL = 0, CPHA = 0) and 3 (CPOL = 1, CPHA = 1), as explicitly stated in its Features section. It does not support Mode 1 (CPOL = 0, CPHA = 1) or Mode 2 (CPOL = 1, CPHA = 0). Attempting to use unsupported modes will result in misaligned data sampling and corrupted communication, because the device's internal shift register is hardwired to sample on the first edge and output on the second edge of each clock cycle.

How does the HOLD pin function during an active write cycle in AT25256A-10TI-1.8?

The HOLD pin has no effect during an active internal write cycle (tWC = 5 ms) in AT25256A-10TI-1.8. Once the WRITE instruction completes and CS goes high, the device enters self-timed programming; HOLD assertion during this phase is ignored. HOLD only functions during active SPI communication (CS low, SCK toggling) to pause data transfer. To monitor write progress, use RDSR to check the RDY bit - it returns 1 until programming finishes.

Can AT25256A-10TI-1.8 be used with a 3.3 V microcontroller without level shifting?

Yes, AT25256A-10TI-1.8 is fully compatible with 3.3 V microcontrollers: its VCC range (1.8–5.5 V) includes 3.3 V, and its input thresholds (VIH ≥ 0.7×VCC, VIL ≤ 0.3×VCC) ensure reliable logic recognition at 3.3 V (VIH ≥ 2.31 V, VIL ≤ 0.99 V). Its SO output drives VOH ≥ VCC − 0.2 V (≥3.1 V) and VOL ≤ 0.2 V, meeting 3.3 V CMOS input requirements without external level shifters.

What happens if the WP pin is tied low while WPEN = 0 in AT25256A-10TI-1.8?

When WPEN = 0 in the status register, the WP pin is disabled regardless of its voltage level - so tying WP low has no protective effect. All write operations (including to the status register itself) remain enabled. This configuration allows safe installation in systems where WP is grounded by default, while retaining full programmability. To activate hardware protection, WPEN must first be set to 1 via WRSR, after which WP low will lock status register and protected memory blocks.