Microchip Technology AT25256A-10TU-1.8

Overview

AT25256A-10TU-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 20 MHz clock rate at 5 V, and packaged in an 8-lead TSSOP. It features hardware write protection via WP pin, HOLD pin for communication suspension, and block write protection covering 1/4, 1/2, or entire memory array. It is used in industrial control modules for nonvolatile parameter storage with low-voltage operation.

For engineers reviewing the AT25256A-10TU-1.8 datasheet, AT25256A-10TU-1.8 pinout, AT25256A-10TU-1.8 application, or AT25256A-10TU-1.8 equivalent, key selection criteria include 1.8 V minimum supply voltage, TSSOP-8 package compatibility, SPI Mode 0/3 support, 64-byte page write capability, and hardware/software dual write protection architecture.

Technical Context

The AT25256A-10TU-1.8 implements a synchronous SPI slave interface with separate SI (input) and SO (output) pins, requiring CS assertion and MSB-first data framing. Its instruction set includes WREN, WRDI, RDSR, WRSR, READ, and WRITE op-codes, all initiated by CS falling edge.

Internal architecture includes a nonvolatile status register with BP0/BP1 for block protection and WPEN for hardware write protect enable/disable, plus a self-timed 5 ms max write cycle with no external erase required. The device supports industrial temperature range (−40°C to +85°C) and is RoHS-compliant with halogen-free packaging.

Key Specifications

Pinout & Package

AT25256A-10TU-1.8 is housed in an 8-lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153 compliant, with 0.65 mm lead pitch and 4.4 mm × 3.0 mm body dimensions. Pin 1 is marked by a beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95256-DW and BR25H256FJ-WE2, AT25256A-10TU-1.8 uniquely combines HOLD pin suspend capability, hardware WP pin with configurable WPEN, and full SPI Mode 0/3 interoperability - making it optimal for designs requiring robust, low-latency, interruptible configuration storage in space-constrained industrial layouts.

Availability

AT25256A-10TU-1.8 is available at Aetrix Electronics and suitable for industrial control systems, medical sensor calibration modules, smart energy metering, and automotive body electronics requiring stable component supply across extended product lifecycles.

Supply support for AT25256A-10TU-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 a focus on embedded control and connectivity.

The AT25256A-10TU-1.8 belongs to Microchip's legacy Atmel SPI EEPROM family, designed specifically for reliable, low-power nonvolatile data storage in industrial, medical, and infrastructure applications where voltage flexibility and hardware-based data protection are essential.

FAQ

What is the minimum supply voltage required for reliable operation of the AT25256A-10TU-1.8?

The AT25256A-10TU-1.8 operates reliably down to 1.8 V, as confirmed by DC characteristics Table 1-2 (VCC1 min = 1.8 V). This enables direct integration with 1.8 V logic families and ultra-low-power microcontrollers without voltage translation. Operation below 1.8 V is not guaranteed and may result in undefined behavior or failed write cycles. The AT25256A-10TU-1.8 maintains full functionality-including 20 MHz clock support at 5 V and 5 ms write timing-across its entire 1.8 V to 5.5 V range.

Does the AT25256A-10TU-1.8 support both SPI Mode 0 and Mode 3, and how is this selected?

Yes, the AT25256A-10TU-1.8 supports both SPI Mode 0 (CPOL = 0, CPHA = 0) and Mode 3 (CPOL = 1, CPHA = 1), as explicitly stated in the Features section. No configuration or pin setting is required-the device automatically adapts to the master's clock polarity and phase. Mode selection is determined solely by the host controller's SPI peripheral configuration; the AT25256A-10TU-1.8 functions as a passive slave with no internal mode register. This dual-mode support ensures compatibility with a broad range of MCUs without firmware adaptation.

How does the HOLD pin function during an active SPI transaction on the AT25256A-10TU-1.8?

The HOLD pin on the AT25256A-10TU-1.8 suspends serial communication without resetting the internal address counter or command state. To activate HOLD, the pin must be driven low while SCK is low; the SO pin enters high-impedance, and SI inputs are ignored. Communication resumes when HOLD is returned high while SCK remains low. This allows the host to pause reads/writes-for example, to service a higher-priority interrupt-then continue seamlessly from the exact bit position where paused. The AT25256A-10TU-1.8 retains full context throughout the HOLD period.

Can the AT25256A-10TU-1.8 be used in automotive applications, and what qualifications does it hold?

The AT25256A-10TU-1.8 is rated for industrial temperature (−40°C to +85°C) and is not qualified to AEC-Q100 or automotive-grade reliability standards. While its operating range overlaps with some automotive cabin environments, Microchip's official documentation states "Atmel's products are not intended, authorized, or warranted for use as components in applications intended to support or sustain life." For automotive body control units or infotainment systems, designers should select automotive-qualified alternatives such as the AT25256AN-10SU-1.8 (AEC-Q100 Grade 3) or equivalent. The AT25256A-10TU-1.8 is intended for industrial and commercial use only.

What is the purpose of the WPEN bit in the status register of the AT25256A-10TU-1.8?

The WPEN (Write Protect Enable) bit (Bit 7) in the AT25256A-10TU-1.8 status register controls whether the hardware WP pin affects write protection. When WPEN = 0, the WP pin is disabled and has no effect-even if pulled low, status register and memory writes remain enabled. When WPEN = 1, the WP pin becomes active: pulling it low blocks all status register writes (including BP0/BP1 and WPEN itself) and protects block-locked memory regions. This allows flexible system design-e.g., grounding WP during manufacturing while retaining software configurability via WRSR-without permanent hardware lockout. The AT25256A-10TU-1.8 preserves this behavior across power cycles since WPEN is nonvolatile.