Microchip Technology AT25640A-10TU-1.8

Overview

AT25640A-10TU-1.8 from Microchip Technology (formerly Atmel) is a 64 Kbit SPI serial EEPROM organized as 8192 × 8 bits, supporting 1.8 V to 5.5 V supply, 20 MHz clock rate at 5 V, 32-byte page write, and hardware/software write protection. It serves as nonvolatile configuration storage in industrial control modules requiring low-voltage operation and long data retention.

For engineers reviewing the AT25640A-10TU-1.8 datasheet, AT25640A-10TU-1.8 pinout, AT25640A-10TU-1.8 application, or AT25640A-10TU-1.8 equivalent, key selection criteria include 1.8 V minimum operating voltage, TSSOP-8 package compatibility, SPI Mode 0/3 support, block write protection granularity, and 1 million endurance cycles.

Technical Context

The AT25640A-10TU-1.8 operates as an SPI slave device with dedicated SI/SO pins, CS-controlled selection, and HOLD pin for serial communication suspension without reset. Its status register implements nonvolatile BP0/BP1 bits for 0%, 25%, 50%, or 100% array protection and WPEN bit enabling hardware write protection via the WP pin.

Internal self-timed write cycles complete in ≤5 ms; no external erase command is required. The device supports both standard (2.7–5.5 V) and low-voltage (1.8–5.5 V) operation modes, with distinct DC/AC timing specifications per voltage range - including tWH/tWL of 20 ns (4.5–5.5 V), 40 ns (2.7–5.5 V), or 80 ns (1.8–5.5 V).

Key Specifications

Pinout & Package

AT25640A-10TU-1.8 is supplied in an 8-lead TSSOP package (JEDEC MO-153, 4.4 mm body width), RoHS-compliant and lead-free, with 0.65 mm pitch and exposed pad not present.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95640-DW and BR24G64FJ-3GE2, AT25640A-10TU-1.8 uniquely combines HOLD pin support, hardware WP, and 1M-cycle endurance at 1.8 V - making it optimal for real-time industrial controllers requiring deterministic SPI behavior and long-term field reliability.

Availability

AT25640A-10TU-1.8 is available at Aetrix Electronics and suitable for industrial automation, medical diagnostics, and automotive body electronics requiring stable component supply, extended temperature operation, and long-lifecycle support.

Supply support for AT25640A-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 nonvolatile memory solutions, with broad industrial and automotive qualifications.

The AT25640A-10TU-1.8 belongs to Microchip's legacy Atmel serial EEPROM family, designed specifically for robust, low-power, SPI-based configuration and parameter storage in space-constrained embedded systems.

FAQ

What is the minimum supply voltage supported by the AT25640A-10TU-1.8?

The AT25640A-10TU-1.8 supports a minimum supply voltage of 1.8 V across its full operating temperature range (–40 °C to +85 °C). This is confirmed in the DC Characteristics table (VCC1 parameter), enabling direct interface with 1.8 V logic families without level shifting. Operation below 1.8 V is not guaranteed and may result in undefined behavior or failure to execute write cycles. The AT25640A-10TU-1.8 maintains full AC timing compliance and 20 MHz clock capability only at 5 V; at 1.8 V, maximum clock rate is 5 MHz.

Does the AT25640A-10TU-1.8 support SPI Mode 0 and Mode 3 simultaneously?

The AT25640A-10TU-1.8 is compatible with both SPI Mode 0 (CPOL = 0, CPHA = 0) and Mode 3 (CPOL = 1, CPHA = 1), but it does not auto-detect or switch between them. The host controller must configure its SPI peripheral to match the selected mode before initiating communication. Mode 0 is the default and most widely tested configuration per the datasheet. Using Mode 3 requires verifying timing margins (especially tWH/tWL) at the target VCC and temperature, as some AC parameters differ slightly between modes. The AT25640A-10TU-1.8 itself contains no internal mode-selection logic.

How is block write protection configured on the AT25640A-10TU-1.8?

Block write protection on the AT25640A-10TU-1.8 is configured by writing to Bits BP0 and BP1 in the nonvolatile status register using the WRSR instruction. These bits define four protection levels: 0% (BP1=0, BP0=0), 25% (BP1=0, BP0=1), 50% (BP1=1, BP0=0), or 100% (BP1=1, BP0=1) of the 8192-word array. Protection applies only to write operations; reads remain unrestricted. The WPEN bit (Bit 7) must be set to "1" to enable hardware protection via the WP pin. The AT25640A-10TU-1.8 retains these settings through power cycles.

What is the function of the HOLD pin on the AT25640A-10TU-1.8?

The HOLD pin on the AT25640A-10TU-1.8 suspends ongoing SPI communication without resetting the internal address counter or command state. When asserted low (while SCK is low), it places SO in high-impedance and ignores SI inputs, preserving the exact point in a multi-byte read or write sequence. This allows the host microcontroller to service higher-priority interrupts and resume the exact same transaction upon deassertion. Unlike CS, HOLD does not terminate the command - the AT25640A-10TU-1.8 remains selected and ready to continue immediately after HOLD returns high.

Is the AT25640A-10TU-1.8 pin-compatible with other variants in the AT25xxxA family?

Yes, the AT25640A-10TU-1.8 shares identical pinout, package dimensions, and electrical characteristics with other AT25xxxA variants offered in the TSSOP-8 (8A2) package, including AT25080A-10TU-1.8, AT25160A-10TU-1.8, and AT25320A-10TU-1.8. All use the same 8-pin mapping (CS, SO, WP, GND, VCC, HOLD, SCK, SI) and mechanical footprint. This allows board-level scalability - designers can select memory density based on application needs without modifying PCB layout or firmware pin assignments. Voltage and timing specs are consistent across the family in the –1.8 suffix variants.