24LC256 Pinout
24LC256 I²C EEPROM · 256-kbit (32KB) I²C serial EEPROM. Up to 8 devices on one bus via the address pins.
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | A0 | Input | I²C address bit 0 |
| 2 | A1 | Input | I²C address bit 1 |
| 3 | A2 | Input | I²C address bit 2 |
| 4 | VSS · GND | GND | Ground |
| 5 | SDA | I/O | I²C serial data (needs pull-up) |
| 6 | SCL | Input | I²C serial clock (needs pull-up) |
| 7 | WP | Control | Write protect (high = read-only; tie low to write) |
| 8 | VCC | Power | Supply + (2.5–5.5V) |
How to read the 24LC256 pinout
- 01
Find pin 1
One end of the chip has a half-circle notch or a dot; with the notch facing up, the top-left pin is pin 1.
- 02
Count counter-clockwise
Count counter-clockwise from pin 1: go down the left side first, then up the right side from the bottom.
- 03
Check the table below
Look up each pin's function by number in the table below; power/ground are color-coded, and alternate-function signals are in parentheses.
Frequently asked questions
What I²C address does the 24LC256 use?
Base 0x50, with A2:A1:A0 setting the low three bits — so 0x50 to 0x57. This lets up to 8 chips coexist on one bus.
How do I make it read-only?
Tie WP (pin 7) high. To allow writes, tie WP to GND. Leaving WP floating is not allowed.
Why are my writes failing without resistors on SDA/SCL?
I²C is open-drain — both SDA and SCL need pull-up resistors (typically 4.7kΩ) to VCC. Without them the bus cannot return high.
Pinout data comes from Microchip 24LC256 datasheet (standard DIP-8 numbering). Refer to the actual device datasheet as authoritative for the pinout.