Microchip 25LC256T-E/SN16KVAO 256K SPI Bus Serial EEPROM: Datasheet, Pinout, and Application Circuit Guide

The Microchip 25LC256T-E/SN16KVAO is a 256-Kbit serial Electrically Erasable Programmable Read-Only Memory (EEPROM) that utilizes the widely adopted Serial Peripheral Interface (SPI) bus for communication. This device is renowned for its high reliability, low power consumption, and simple interface, making it a cornerstone for data storage in countless embedded systems, from consumer electronics to industrial automation.

This guide provides a concise overview of its key specifications, pinout configuration, and a fundamental application circuit to facilitate easy integration into your designs.

Datasheet Highlights and Key Features

The datasheet for the 25LC256T-E/SN delineates a robust and versatile memory solution. Its core characteristics include:

Capacity: Organized as 32,768 x 8 bits, it provides 256 Kbits of secure, non-volatile data storage.

SPI Interface: Supports all four modes of SPI operation (Mode 0,0 and Mode 1,1) and features a clock frequency of up to 10 MHz, enabling high-speed data transfers.

Low-Power Operation: Ideal for battery-powered devices, it boasts a low standby current (1 µA typical) and an active current of 3 mA during a write operation.

Hardware Write Protection: The WP (Write Protect) pin allows the user to disable all write operations to the status register and memory array, safeguarding critical data.

Software Data Protection: An optional feature that can be enabled via the status register to prevent inadvertent writes.

High Endurance: Guaranteed for 1,000,000 erase/write cycles per sector and a data retention period of over 200 years.

Wide Voltage Range: Operates from 1.8V to 5.5V, ensuring compatibility with both 3.3V and 5V microcontroller systems.

Temperature Range: The -E suffix denotes an extended industrial temperature range of -40°C to +125°C, suitable for harsh environments.

Pinout Configuration (SOIC-8 Package)

The 25LC256T-E/SN is offered in an 8-lead SOIC package. The pin functions are as follows:

1. CS (Chip Select): Active-low input used to select the device when pulled low, enabling communication.

2. SO (Serial Data Output): The data output pin. Data is clocked out on the falling edge of the SCK signal.

3. WP (Write Protect): Active-low input. When driven low, it disables write operations to the status register and memory array.

4. VSS (Ground): Circuit ground reference (0V).

5. SI (Serial Data Input): The data input pin. Instructions, addresses, and data are clocked in on the rising edge of SCK.

6. SCK (Serial Clock Input): Provides the timing for all data input and output operations.

7. HOLD: Active-low input. Pausing the serial communication without deselecting the device is possible by pulling this pin low.

8. VCC: Positive supply voltage input (1.8V to 5.5V).

Basic Application Circuit Guide

A typical connection circuit between the 25LC256T-E/SN and an MCU is straightforward, highlighting the simplicity of the SPI bus.

VCC and VSS are connected to the MCU's power supply (e.g., 3.3V) and ground, respectively. A 0.1µF decoupling capacitor should be placed close to the VCC pin to filter noise.

The four primary SPI signals (CS, SCK, SI, SO) are connected directly to the corresponding SPI pins on the MCU.

To utilize hardware write protection, the WP pin can be connected to a general-purpose I/O (GPIO) pin of the MCU. To disable protection, this pin can be left disconnected or tied high to VCC.

The HOLD pin, if used, can also be controlled by a MCU GPIO. For basic operation, it can be tied directly to VCC to disable the hold function.

This simple 4-wire interface (plus power) allows the MCU to perform byte-level and page-level read/write operations, read from the status register, and execute other commands as specified in the datasheet.

ICGOODFIND Summary:

The Microchip 25LC256T-E/SN16KVAO stands out as an industry-standard SPI EEPROM, offering a perfect blend of density, speed, and reliability. Its straightforward interface, comprehensive protection features, and wide operating voltage make it an exceptionally versatile choice for designers needing robust non-volatile memory in a small form factor.

Keywords:

SPI EEPROM

Non-volatile Memory

Serial Peripheral Interface

Hardware Write Protection

Embedded Systems