Microchip 93C46B-I/SN 4K Microwire Serial EEPROM: Datasheet, Pinout, and Application Circuit Guide
The Microchip 93C46B-I/SN is a 4K-bit Microwire serial Electrically Erasable Programmable Read-Only Memory (EEPROM) housed in an 8-lead SOIC package. This non-volatile memory solution is renowned for its reliability, low power consumption, and simple 3-wire interface, making it a popular choice for storing configuration data, calibration constants, and other critical information in a vast array of industrial, automotive, and consumer applications.
Datasheet Overview and Key Features
The device's datasheet details its robust characteristics. Organized as 512 x 8 or 256 x 16, it offers flexibility in data organization. It supports a wide voltage range from 2.5V to 5.5V, enabling operation in both 3.3V and 5.0V systems. Its low power consumption is highlighted by a standby current of just 1 µA (max) and an active current of 1 mA (max) during read operations. Key features include:
Microwire Serial Interface: A simple, synchronous 3-wire (CS, SK, DI) protocol for communication.
Sequential Read Operation: Allows for efficient reading of consecutive memory addresses.
Self-Timed Write Cycle: The internal circuitry automatically controls the write pulse timing, simplifying microcontroller (MCU) management.
High Reliability: Features 1,000,000 erase/write cycles and 100 years of data retention.
Built-in Write Protection: Enabled via a specific instruction and controlled by the `ORG` pin to prevent accidental data corruption.
Pinout Configuration
Understanding the pinout is crucial for circuit design. The 93C46B-I/SN is an 8-pin IC with the following pin functions:
1. CS (Chip Select): Active-high input that initiates and terminates a command sequence. All operations require this pin to be held high.
2. SK (Serial Clock): Input pin that clocks data in and out of the device. Data is shifted on the rising edge of SK.
3. DI (Data In): The command and data input pin. Instructions and data to be written are serially fed into this pin.
4. DO (Data Out): The data output pin. During read operations, data is shifted out serially on this pin.
5. GND (Ground): Circuit ground reference (0V).
6. ORG (Memory Organization): This pin sets the internal organization. Tied to VCC for 16-bit organization or to GND for 8-bit organization.
7. NC (No Connect): This pin is not internally connected and can be left floating.
8. VCC (Power Supply): The positive power supply input (2.5V to 5.5V).
Application Circuit Guide
Integrating the 93C46B-I/SN into a design is straightforward. A typical application circuit connecting it to a microcontroller (MCU) is shown below.
A basic connection diagram for the 93C46B-I/SN.
Key Design Considerations:
1. Power Supply Decoupling: A 0.1 µF ceramic capacitor should be placed as close as possible between the VCC (pin 8) and GND (pin 5) pins to filter high-frequency noise and ensure stable operation.
2. Pull-Up Resistor: The DO (pin 4) output is open-drain. An external 10 kΩ pull-up resistor to VCC is required for proper operation.
3. Organization Selection: The ORG (pin 6) must be tied firmly to either VCC (for 16-bit mode) or GND (for 8-bit mode). This decision must match the software command protocol.
4. Unused Pin: The NC (pin 7) can be left unconnected.
5. Signal Lines: The CS, SK, and DI lines are driven directly from the MCU's GPIO pins. While not always necessary for short traces, series resistors (e.g., 100Ω) can be added to limit current and reduce EMI.
Software Communication (Instruction Set)
Communication is performed by sending 16-bit instructions (in 8-bit mode, instructions are sent as two 8-bit bytes). Key instructions include:
READ (Address): Reads data from a specified memory address.
EWEN (Erase/Write Enable): Must be sent before any write or erase operation to disable the software write protection.
WRITE (Address, Data): Writes data to a specified address.
ERASE (Address): Erases (sets to all 1's) a specified address.
ERAL (Erase All): Erases the entire memory array.
WRAL (Write All): Writes the same data to all memory locations.
The Microchip 93C46B-I/SN stands as a quintessential serial EEPROM solution, prized for its proven reliability, straightforward Microwire interface, and exceptional low-power performance. Its flexibility in data organization and robust built-in protection features make it an ideal choice for designers seeking a dependable non-volatile memory component for data logging, system configuration, and parameter storage across diverse electronic applications.
Keywords:
1. Microwire Interface
2. Serial EEPROM
3. Non-Volatile Memory
4. Low-Power Consumption
5. Data Retention
