25LC256 256 Kbit SPI EEPROM

Microchip 25LC256 256 Kbit (32 KB) SPI serial EEPROM in PDIP-8 package, operating from 2.5–5.5V. SPI modes 0,0 and 1,1; 64-byte page write buffer; 1 million write cycle endurance. 25AA256 is the lower-voltage variant (1.8V).

Logical pinout · physical placement not verified

VCC
Supply voltage 2.5–5.5 V; connect to 3.3 V rail
Type · PowerVoltage · 3.3
VSS
Ground
Type · Ground
CS
Chip Select (active LOW); connect to dedicated GPIO CS pin
Type · SPI
SCK
SPI clock from Pico SPI peripheral
Type · SPI
MOSI
SPI data in (SI on device); connect to Pico MOSI
Type · SPI
MISO
SPI data out (SO on device); connect to Pico MISO
Type · SPI
WP
Write Protect (active LOW); tie HIGH to VCC to allow writes
Type · GPIOVoltage · 3.3
HOLD
Hold (active LOW); tie HIGH to VCC for normal operation
Type · GPIOVoltage · 3.3

Pin	Type	Function	Voltage
VCC	Power	Supply voltage 2.5–5.5 V; connect to 3.3 V rail	3.3
VSS	Ground	Ground
CS	SPI	Chip Select (active LOW); connect to dedicated GPIO CS pin
SCK	SPI	SPI clock from Pico SPI peripheral
MOSI	SPI	SPI data in (SI on device); connect to Pico MOSI
MISO	SPI	SPI data out (SO on device); connect to Pico MISO
WP	GPIO	Write Protect (active LOW); tie HIGH to VCC to allow writes	3.3
HOLD	GPIO	Hold (active LOW); tie HIGH to VCC for normal operation	3.3

Logical pinout · physical placement not verified

Pin details

8 connections

VCC
Supply voltage 2.5–5.5 V; connect to 3.3 V rail
PowerVoltage · 3.3
VSS
Ground
Ground
CS
Chip Select (active LOW); connect to dedicated GPIO CS pin
SPI
SCK
SPI clock from Pico SPI peripheral
SPI
MOSI
SPI data in (SI on device); connect to Pico MOSI
SPI
MISO
SPI data out (SO on device); connect to Pico MISO
SPI
WP
Write Protect (active LOW); tie HIGH to VCC to allow writes
GPIOVoltage · 3.3
HOLD
Hold (active LOW); tie HIGH to VCC for normal operation
GPIOVoltage · 3.3

Memory

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