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).

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 · digitalVoltage · 3.3
HOLD
Hold (active LOW); tie HIGH to VCC for normal operation
Type · digitalVoltage · 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	digital	Write Protect (active LOW); tie HIGH to VCC to allow writes	3.3
HOLD	digital	Hold (active LOW); tie HIGH to VCC for normal operation	3.3

Memory

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