Microchip 93C46BT/SN 16-bit 1K Serial EEPROM: Features and Application Design Guide

The Microchip 93C46BT/SN is a 1K-bit Microwire serial Electrically Erasable Programmable Read-Only Memory (EEPROM) organized as 64 words of 16 bits each. This non-volatile memory solution is renowned for its reliability, low power consumption, and simple serial interface, making it an ideal choice for storing critical calibration data, configuration settings, and identification parameters in a vast array of embedded systems.

Key Features and Specifications

The 93C46BT/SN stands out due to a robust set of features designed for ease of integration and dependable long-term operation.

Microwire Serial Interface: This simple, 3-wire (CS, SK, DI) serial protocol facilitates communication with a wide range of microcontrollers (MCUs) and processors with minimal I/O pin requirements. A fourth pin (DO) is used for data output.

Wide Voltage Operation: It supports a broad operating voltage range from 2.5V to 5.5V, enabling its use in both 3.3V and 5V systems without the need for level shifters.

Low Power Consumption: The device is optimized for power-sensitive applications, featuring low active current and a standby current of just 1 µA (typical), which is crucial for battery-powered devices.

High Reliability: It offers an endurance of 1 million erase/write cycles per word and data retention of over 200 years, ensuring data integrity throughout the product's lifespan.

Software and Hardware Compatibility: This device is a direct second-source compatible replacement for other industry-standard 93C46 EEPROMs, simplifying design-in and mitigating supply chain risks.

Sequential Read Operation: This feature allows for faster data transfer when reading consecutive memory addresses.

Self-Timed Write Cycle: The internal timer automates the write pulse duration, simplifying software management and ensuring correct programming timing.

Application Design Guide

Successfully integrating the 93C46BT/SN into a design requires attention to several key areas:

1. Interface and Connection:

The primary connections between the MCU and the EEPROM are straightforward:

Chip Select (CS): Driven by an MCU I/O pin to initiate and terminate a command sequence.

Serial Clock (SK): Generated by the MCU to synchronize data shifting in and out.

Data Input (DI): The line for the MCU to send opcodes, addresses, and data to the EEPROM.

Data Output (DO): The line for the EEPROM to send data back to the MCU.

It is critical to include pull-up resistors on the DI, DO, and CS lines (typically 10 kΩ) to ensure stable logic-high levels. For environments with high electrical noise, decoupling capacitors (100 nF) placed close to the VCC and GND pins of the EEPROM are essential.

2. Command Sequencing:

All operations are initiated by a start bit (a high logic level on DI with CS high and a rising edge on SK). This is followed by a specific opcode and a memory address. For write operations, this is followed by the 16-bit data word. Designers must strictly adhere to the timing diagrams provided in the datasheet for each command (READ, WRITE, WREN, ERASE, etc.).

3. Write Protection and Control:

The Write Enable (WREN) command must be issued before any programming (Write or Erase) operation to prevent accidental data corruption. The device will power up in a write-disable state. Furthermore, the ORG pin (or its software equivalent) must be correctly configured to match the desired organization mode (16-bit or optional 8-bit).

4. Handling Busy Status:

After initiating a write cycle, the EEPROM becomes busy. The MCU can poll the DO pin; while busy, DO is low. The MCU must wait until DO goes high before issuing any new commands to avoid communication errors.

5. PCB Layout Considerations:

Keep the traces between the MCU and the EEPROM as short as possible to minimize noise coupling and signal integrity issues. A solid ground plane is highly recommended.

Conclusion

The Microchip 93C46BT/SN provides a perfect blend of simplicity, endurance, and non-volatile storage for modern electronic designs. Its Microwire interface ensures broad compatibility, while its impressive specifications for power, reliability, and data retention make it a trusted component in automotive, industrial, consumer, and medical applications. By following the essential design practices outlined above, engineers can seamlessly integrate this EEPROM to achieve robust and reliable data storage.

ICGOODFIND: The Microchip 93C46BT/SN is a highly reliable and industry-standard 16-bit serial EEPROM. Its wide voltage range, ultra-low standby current, and simple 3-wire interface make it an excellent choice for storing configuration data in space-constrained and power-sensitive designs across numerous markets.

Keywords: Serial EEPROM, Microwire Interface, Non-volatile Memory, Low Power Consumption, Data Retention.