Microchip Technology AT25640B-MAHL-T

Overview

AT25640B-MAHL-T from Microchip Technology (formerly Atmel) is a 64-kbit SPI serial EEPROM organized as 8,192 words × 8 bits, operating from 1.8V to 5.5V with 20MHz max clock rate at 5V, 32-byte page write capability, and hardware/software write protection via WP pin and status register. It serves in industrial control systems for storing calibration data, configuration parameters, and firmware boot flags.

For engineers reviewing the AT25640B-MAHL-T datasheet, AT25640B-MAHL-T pinout, AT25640B-MAHL-T application, or AT25640B-MAHL-T equivalent, key selection criteria include its 8-pad UDFN (2.0 × 3.0 mm) package, -40°C to +85°C industrial temperature range, 1,000,000 write endurance, 100-year data retention, and support for SPI Modes 0 and 3.

Technical Context

The AT25640B-MAHL-T implements a synchronous slave SPI interface with dedicated SI (input), SO (output), SCK (clock), CS (chip select), WP (write protect), and HOLD (communication suspend) pins. Its internal architecture includes an 8-bit instruction register, status register with BP0/BP1/WE/WPEN bits, and automatic address incrementing during sequential reads/writes.

Block write protection is configurable via status register to lock 0%, 25%, 50%, or 100% of the 64Kb memory array (0000h–1FFFh). All write cycles are self-timed (≤5ms), require prior WREN instruction, and permit only RDSR during active programming - enabling deterministic timing in real-time embedded systems.

Key Specifications

Pinout & Package

AT25640B-MAHL-T uses an 8-pad, 2.0 mm × 3.0 mm, 0.50 mm pitch Ultra Thin Dual Flat No-Lead (UDFN) package (JEDEC MO-229 compliant), optimized for space-constrained PCB layouts in portable and IoT edge devices.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M95640-DRMN6TP/K and BR24G64FJ-3GE2, AT25640B-MAHL-T delivers optimal balance of SPI-native performance, compact UDFN footprint, and industrial reliability - making it preferred for space-constrained, SPI-centric embedded systems where deterministic timing and low-power standby are essential.

Availability

AT25640B-MAHL-T is available at Aetrix Electronics and suitable for industrial sensor calibration, smart meter configuration storage, medical device settings backup, and PLC I/O module parameterization requiring stable component supply across multi-year production cycles.

Supply support for AT25640B-MAHL-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 product support, documentation, and manufacturing continuity for the AT25xxxB EEPROM family.

The AT25640B-MAHL-T belongs to Microchip's legacy SPI serial EEPROM product line, designed specifically for reliable, low-voltage, high-endurance nonvolatile storage in industrial and commercial embedded systems where SPI interface simplicity and small footprint are critical.

FAQ

What is the maximum clock frequency supported by the AT25640B-MAHL-T at 3.3V operation?

The AT25640B-MAHL-T supports up to 10 MHz SCK frequency at VCC = 2.5–5.5V (per Table 4-3 AC Characteristics), and 5 MHz at VCC = 1.8–3.6V. At 3.3V, the guaranteed maximum is 10 MHz - sufficient for sub-100 µs byte reads and efficient page writes in most microcontroller implementations.

Does the AT25640B-MAHL-T require an external pull-up resistor on the SO pin?

No, the AT25640B-MAHL-T SO pin has an internal active pull-up and operates in true tri-state mode. When CS is high or HOLD is asserted, SO enters high-impedance state - eliminating need for external pull-up and preventing bus contention in multi-slave SPI configurations.

How is block write protection configured on the AT25640B-MAHL-T?

Block write protection on the AT25640B-MAHL-T is set by writing to the status register using the WRSR instruction. Bits BP1 and BP0 determine protected memory ranges: 00 = none, 01 = lower 1/4 (1800h–1FFFh), 10 = lower 1/2 (1000h–1FFFh), 11 = full array (0000h–1FFFh). WPEN bit must be 1 for hardware WP pin to take effect.

What is the purpose of the HOLD pin on the AT25640B-MAHL-T, and how is it used?

The HOLD pin on the AT25640B-MAHL-T suspends ongoing SPI communication without resetting the internal state. To pause, drive HOLD low while SCK is low; to resume, drive HOLD high while SCK remains low. This allows the host MCU to service higher-priority interrupts mid-transfer - preserving data integrity and timing predictability.

Is the AT25640B-MAHL-T RoHS compliant and halogen-free?

Yes, the AT25640B-MAHL-T is RoHS compliant and halogen-free, as confirmed by its "H" suffix (NiPdAu lead finish) and "L" voltage designation in the ordering code. It meets EU Directive 2011/65/EU and JEDEC J-STD-609A Class 1 moisture sensitivity level (MSL-1) for unlimited floor life at <30°C/85% RH.