Microchip 25LC160BT-E/SN 16Kb SPI Bus Serial EEPROM: Features and Application Design Guide
The Microchip 25LC160BT-E/SN is a 16-kilobit (2K x 8) Serial EEPROM memory device utilizing the industry-standard SPI serial communications interface. It serves as a reliable non-volatile storage solution for a vast array of applications, from consumer electronics to industrial systems. This design guide explores its key features and provides essential considerations for integrating it into new designs.
Key Features and Specifications
This device stands out due to its combination of performance, flexibility, and reliability:
SPI Bus Compatibility: It supports clock speeds up to 10 MHz, enabling high-speed data transfer. It is compatible with both Mode 0 (0,0) and Mode 3 (1,1) SPI operations.
Advanced Hardware Protection: Features hardware write-protection via a dedicated `WP` pin. When asserted, this pin prevents writes to the status register and the upper quarter of the memory array (180h-1FFh), safeguarding critical data from corruption.
Software Data Protection (SDP): An additional layer of security that prevents accidental writes by requiring a specific write enable sequence before any write command is accepted.
Low-Power Operation: Ideal for battery-powered and portable devices, it boasts a low standby current (1 µA typical) and an active read current of just 3 mA at 10 MHz.
Wide Voltage Range: Operates from 1.8V to 5.5V, making it versatile for use in both 3.3V and 5V systems without needing a level translator.
High Endurance and Retention: Guarantees 1,000,000 erase/write cycles per sector and data retention of over 200 years.
Temperature Range: The 25LC160BT-E/SN is specified for the extended industrial temperature range (-40°C to +85°C), ensuring stable operation in harsh environments.
Compact Package: Offered in an 8-lead SOIC (150-mil) package (SN), it is suitable for space-constrained PCB designs.
Application Design Guide
Successfully integrating the 25LC160BT-E/SN requires attention to several hardware and software aspects.
1. Hardware Interface:
The SPI interface consists of four essential signals:
`CS` (Chip Select): Driven low by the host microcontroller to select and initiate communication with the EEPROM.
`SCK` (Serial Clock): Provides the timing for the serial data transfer. Data is shifted out on the rising or falling edge, depending on the SPI mode.
`SI` (Serial Input)/`MOSI` (Master Out Slave In): The line for transferring data from the microcontroller to the EEPROM.
`SO` (Serial Output)/`MISO` (Master In Slave Out): The line for transferring data from the EEPROM to the microcontroller.
Best Practice: Include pull-up resistors on the `CS` and `WP` lines (typically 10 kΩ) to ensure they are in a known high state during microcontroller reset or power-up. Route all SPI signals to minimize trace length and avoid noise coupling.
2. `WP` and `HOLD` Pin Management:
The `WP` pin must be tied high for normal write operations. It can be driven by a microcontroller GPIO to dynamically enable or disable the hardware protection sector.
The `HOLD` pin allows the host to pause an ongoing serial transmission without resetting the communication sequence. If this feature is unused, it should be tied directly to VCC.
3. Software Implementation:
The core of communication is a set of instruction codes:
`WREN` (Write Enable Latch): Must be issued before every write operation (`WRITE`, `WRSR`).
`READ` (Read Data): Reads data starting from a specified 16-bit address.
`WRITE` (Write Data): Writes data starting from a specified 16-bit address.
`RDSR` (Read Status Register): Crucial for checking the `RDY`/`BUSY` bit before initiating a new write command. The microcontroller must poll this bit until it reads 0, indicating the internal write cycle is complete and the device is ready.
Critical Timing: Always observe the `t_WC` (Write Cycle Time) of 5 ms maximum. The software routine must wait this duration after a write command before checking the status register again to avoid a false `BUSY` reading.
4. Power Supply Decoupling:
Place a 0.1 µF ceramic decoupling capacitor as close as possible to the VCC and GND pins of the EEPROM. This is critical for stabilizing the power supply and minimizing noise during write cycles, which is essential for data integrity.
Conclusion
The Microchip 25LC160BT-E/SN provides a robust, simple, and efficient method for adding non-volatile memory to any embedded design. Its high-speed SPI interface, comprehensive data protection mechanisms, and wide operating voltage make it an excellent choice for designers. By following the hardware layout and software sequencing guidelines outlined above, engineers can ensure reliable and error-free operation in their applications.
ICGOODFIND: The 25LC160BT-E/SN is a top-tier choice for a 16Kb SPI EEPROM, offering an optimal blend of speed, hardware security, and design flexibility for professional embedded systems.
Keywords: SPI EEPROM, Hardware Write-Protection, Non-volatile Memory, Serial Communication, Low-Power Operation.
