Microchip 93LC56BT-E/OT: A Comprehensive Guide to the 2K SPI Microwire Serial EEPROM

Introduction to the 93LC56BT-E/OT

The Microchip 93LC56BT-E/OT is a 2K-bit Microwire Serial Electrically Erasable PROM (EEPROM) organized as 128 x 8-bit or 64 x 16-bit. Housed in a space-saving SOT-23-6 package, this non-volatile memory device is designed for applications requiring reliable and compact data storage. It operates over a broad voltage range (1.8V to 5.5V), making it suitable for a wide array of consumer, industrial, and automotive electronics.

Key Features and Electrical Characteristics

This EEPROM stands out due to its low-power consumption, featuring a standby current of just 1 µA (max) and an active read current of 150 µA at 2.5V. Its endurance of 1,000,000 erase/write cycles and data retention of over 200 years ensure long-term reliability. The device supports both the SPI and the Microwire serial interfaces, providing flexibility for system design. It also includes essential hardware and software data protection mechanisms to prevent inadvertent writes.

Interface and Communication Protocol

The 93LC56BT-E/OT utilizes a simple 3-wire serial interface (CS, SK, DI/DO), making it easy to interface with a host microcontroller (MCU). Communication is initiated by taking the Chip Select (CS) pin high. Instructions, addresses, and data are then clocked in via the Serial Input (DI) pin on the rising edge of the Serial Clock (SK). The protocol supports a set of instructions including READ, WRITE, WREN (Write Enable), WRDI (Write Disable), ERASE, and ERAL (Erase All).

Application Overview

This EEPROM is ideal for storing calibration data, configuration settings, and small datasets in systems where board space is at a premium. Common applications include:

Automotive Systems: Storing VIN numbers, sensor calibration data, and user settings.

Consumer Electronics: Used in smart meters, printers, set-top boxes, and remote controls for parameter storage.

Industrial Control: Maintaining device configuration and operational logs in PLCs and sensors.

Medical Devices: Safely storing critical device identifiers and calibration constants.

A typical application circuit involves direct connection to an MCU's GPIO pins. For example, the CS pin is controlled by the MCU to select the device, the SK pin is driven by the MCU's SPI clock, and the DI/DO line is used for bidirectional data transfer. Proper decoupling capacitors near the VCC pin are critical for stable operation.

Programming Considerations

Before any write or erase operation, the Write Enable Latch must be set by issuing the WREN instruction. The device features a ready/busy polling feature; after initiating a write cycle, the MCU can check the state of the data output (DO) pin to determine when the internal cycle is complete and the device is ready for the next command. This eliminates the need for fixed software delay loops.

Conclusion and Advantages

The Microchip 93LC56BT-E/OT provides a robust, compact, and highly reliable solution for non-volatile memory needs in constrained environments. Its wide voltage range, low power consumption, and simple interface make it a versatile choice for designers across numerous industries.

ICGOODFIND: The Microchip 93LC56BT-E/OT is an excellent choice for designers seeking a miniature, low-power, and highly reliable EEPROM with a simple serial interface for storing critical data in space-constrained applications.

Keywords: EEPROM, Microwire, Serial Interface, Non-volatile Memory, Low-power