Unveiling the 93LC56B-E/SN: A Deep Dive into Microchip’s 2K SPI Microwire Serial EEPROM
In the realm of non-volatile memory solutions for embedded systems, the Microchip 93LC56B-E/SN stands as a reliable and versatile component. This 2K-bit Serial Electrically Erasable PROM (EEPROM), organized as 128 x 8-bit or 64 x 16-bit, is engineered for applications requiring dependable data storage with minimal pin count. Its compatibility with both the industry-standard SPI and Microwire serial interfaces offers designers significant flexibility, making it a popular choice across consumer, automotive, and industrial sectors.
Core Features and Architectural Overview
The 93LC56B-E/SN is designed for low-power operation, featuring a wide voltage range (1.8V to 5.5V), which is crucial for both 5V and modern 3.3V systems. Its architecture supports a 16-byte page write mode, enabling more efficient programming of data blocks compared to single-byte writes. This significantly reduces the total time required to update information in the memory array. Furthermore, the device boasts a self-timed write cycle, which simplifies software management by eliminating the need for the microcontroller to poll the device continuously; the EEPROM internally handles the timing of the ~10ms programming cycle.
A critical feature for data integrity is the built-in write-protect mechanism. By controlling the state of the `CS` (Chip Select) pin during power-up or using specific instruction codes, the device can be hardware or software protected against inadvertent writes, ensuring the stability of stored data. The EEPROM also offers impressive endurance, capable of 1,000,000 erase/write cycles, and data retention of over 200 years, guaranteeing long-term reliability.
Application Notes and Circuit Integration
Integrating the 93LC56B-E/SN into a design is straightforward. The device communicates via a simple 4-wire SPI bus: Chip Select (`CS`), Serial Clock (`SK`), Data In (`DI`), and Data Out (`DO`). This allows it to interface with virtually any modern microcontroller with a hardware SPI module or even through bit-banged GPIOs, providing immense flexibility for systems with limited peripheral pins.
A typical application circuit involves connecting the `CS`, `SK`, `DI`, and `DO` lines directly to the microcontroller's SPI pins. Pull-up resistors on these lines are often recommended for signal integrity. The `ORG` pin is crucial as it determines the memory organization; tying it to VCC selects a 16-bit structure, while connecting it to GND opts for an 8-bit structure. For robust performance in electrically noisy environments, such as automotive or industrial settings, decoupling capacitors (typically 0.1µF and 10µF) placed close to the VCC and GND pins are essential to filter power supply noise.
Key Design Considerations:
Sequential Read: After providing the address, the microcontroller can continue clocking to read sequential memory locations, simplifying the reading of large data blocks.
Page Write Limitation: While the page write buffer is 16 bytes, a critical rule must be observed: a page write operation must not cross a page boundary. The address bits are internally incremented, but if the internal address counter reaches the end of a page, it will wrap around to the beginning of the same page, leading to data corruption.
Write-Enable Latch: Before any write or erase operation, a `WREN` (Write Enable) instruction must be issued to set an internal latch. This latch is automatically reset upon a successful write completion or a `WRDI` (Write Disable) command, adding a layer of safety.
ICGOOODFIND
The Microchip 93LC56B-E/SN is a quintessential serial EEPROM that masterfully balances simplicity, flexibility, and reliability. Its dual-interface capability (SPI/Microwire), low-power operation, and robust data protection features make it an exceptionally versatile solution for a vast array of non-volatile memory needs. Whether storing calibration data, device parameters, or event logs, this EEPROM provides a proven and dependable method for preserving critical information in embedded systems.
Keywords:
1. Serial EEPROM
2. SPI Interface
3. Microwire Protocol
4. Non-Volatile Memory
5. Page Write
