Microchip Technology 24LC64F-E/ST

Overview

24LC64F-E/ST from Microchip Technology Inc. is a 64 Kbit I²C-compatible serial EEPROM organized as 8K × 8-bit memory with hardware write-protect for the upper 1/4 array (1800h–1FFFh), 400 kHz max clock frequency, and operation over -40°C to +125°C. It supports page writes up to 32 bytes, features Schmitt-trigger inputs for noise immunity, and draws ≤1 µA standby current in automotive temperature range.

For engineers reviewing the 24LC64F-E/ST datasheet, 24LC64F-E/ST pinout, 24LC64F-E/ST application, or 24LC64F-E/ST equivalent, key selection considerations include its 2.5–5.5 V supply range, automotive-grade temperature rating, quarter-array hardware write-protection, and compatibility with standard I²C bus timing at 400 kHz under V_CC ≥ 2.5 V.

Technical Context

The 24LC64F-E/ST implements a standard two-wire I²C interface with slave addressing via three hardware-configurable address pins (A0–A2), enabling up to eight devices on a single bus. Its internal architecture includes an 8K × 8-bit nonvolatile memory array, a 32-byte page write buffer, and dedicated control logic for self-timed erase/write cycles.

Write protection is implemented via the WP pin: when tied to V_CC, it inhibits writes to addresses 1800h–1FFFh while permitting full read access. The device uses Schmitt-trigger inputs on SDA and SCL with 50 ns spike suppression and hysteresis of 0.05 V_CC, ensuring robust operation in electrically noisy environments.

Key Specifications

Pinout & Package

24LC64F-E/ST is supplied in an 8-lead TSSOP package (3.0 mm × 4.4 mm, 0.65 mm pitch), RoHS-compliant and Pb-free. Pin 1 is marked with a dot or bevel; orientation follows standard TSSOP conventions with pin 1 at top-left when marking side faces up.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC64F-E/ST, the 24AA64F-I/ST trades automotive temperature capability for sub-2.5 V operation, while the AT24C64D-SSHL-T sacrifices hardware write-protection and AEC-Q100 qualification for faster 1 MHz I²C and wider voltage range-making 24LC64F-E/ST uniquely suited for safety-critical automotive storage where hardware-enforced data integrity is mandatory.

Availability

24LC64F-E/ST is available at Aetrix Electronics and suitable for automotive control units, ADAS subsystems, and industrial PLC modules requiring stable component supply with guaranteed long-term availability and full AEC-Q100 compliance documentation.

Supply support for 24LC64F-E/ST 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 Inc. is a leading provider of microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24LC64F belongs to Microchip's 24XX64F family of I²C serial EEPROMs engineered specifically for automotive and industrial applications demanding extended temperature operation, high endurance, and hardware-level data protection.

FAQ

What is the minimum supply voltage required for reliable operation of the 24LC64F-E/ST?

The 24LC64F-E/ST requires a minimum supply voltage of 2.5 V for guaranteed operation across its full automotive temperature range (-40°C to +125°C). Unlike the 24AA64F variant, it is not specified for operation below 2.5 V. Attempting to power the 24LC64F-E/ST at 1.8 V may result in undefined behavior or failure to respond on the I²C bus. Always verify V_CC remains within 2.5–5.5 V during all operational modes, including transient conditions.

Does the 24LC64F-E/ST support 1 MHz I²C clock frequency?

No, the 24LC64F-E/ST does not support 1 MHz I²C operation. Its maximum clock frequency is 400 kHz when V_CC ≥ 2.5 V. The 1 MHz capability is exclusive to the 24FC64F variant. Using a 1 MHz clock with the 24LC64F-E/ST will violate AC timing specifications-including THIGH, TLOW, and TSU:DAT-and likely cause communication failures or corrupted writes. For 1 MHz applications, select the 24FC64F-E/ST instead.

How does the hardware write-protect feature work on the 24LC64F-E/ST?

The WP pin on the 24LC64F-E/ST enables hardware write-protection for the upper 1/4 memory array (addresses 1800h–1FFFh). When WP is tied to V_CC, write commands to this region are ignored-though the device still acknowledges the command-and no data is altered. Reads remain fully functional. Protection is sampled only at the Stop condition of each write command; toggling WP mid-cycle has no effect. This allows secure storage of calibration constants or security keys independent of firmware logic.

Can multiple 24LC64F-E/ST devices share the same I²C bus?

Yes, up to eight 24LC64F-E/ST devices can operate on the same I²C bus using hardwired A0, A1, and A2 pins to configure unique 7-bit slave addresses (1010xxx0 for writes, 1010xxx1 for reads). Each device must have a distinct combination of A0–A2 logic levels (VSS or VCC). The TSSOP package includes all three address pins; ensure proper termination and bus capacitance (<400 pF) is maintained when expanding beyond four devices to preserve signal integrity at 400 kHz.

What is the typical write cycle time for a full 32-byte page on the 24LC64F-E/ST?

The typical write cycle time for a full 32-byte page on the 24LC64F-E/ST is 5 ms, as specified in the datasheet (parameter TWC). This is a self-timed internal operation-no external delay is required beyond issuing the Stop condition. During this period, the device does not acknowledge I²C start conditions (ACK polling is used to detect completion). Page write time remains constant regardless of byte count (1–32 bytes), making it more efficient than sequential byte writes for bulk updates.