Overview

The AT24C32 (commonly AT24C32D or AT24C32N in SOIC-8 or DIP-8) is a 32 Kbit32\text{ Kbit} (4,096 Bytes4,096\text{ Bytes}) I2C serial EEPROM IC manufactured by Microchip Technology (originally Atmel). Organised as 4,096 8-bit bytes with a 32-byte page write buffer, it operates across a wide voltage supply range of 1.7 V1.7\text{ V} to 5.5 V5.5\text{ V}.

Extremely popular in maker projects, the AT24C32 is standard equipment on ubiquitous DS3231 RTC breakout boards, providing dedicated non-volatile memory for data logging, timestamp storage, and persistent system configuration without consuming microcontroller internal EEPROM.

Quick reference

Memory Type32-Kbit Serial I2C Non-Volatile EEPROM
Package8-Pin DIP (Through-Hole) / SOIC-8 / DS3231 RTC Board Component
Supply Voltage Range (VCCV_{CC})1.7 V1.7\text{ V} to 5.5 V5.5\text{ V} DC
Memory Capacity32 Kbits32\text{ Kbits} (4 Kbytes4\text{ Kbytes} / 4,096 Bytes4,096\text{ Bytes})
Page Write Buffer32 Bytes32\text{ Bytes} page write buffer
I2C Clock Speed400 kHz400\text{ kHz} Fast Mode at VCC≥2.5VV_{CC} \ge 2.5\text{V}
Default RTC Board I2C Address0x57 (Address pins A0,A1,A2A_0, A_1, A_2 usually pulled HIGH via solder jumpers)
Endurance & Retention1,000,000 write cycles / >100 years>100\text{ years} data retention

Pinout (8-Pin DIP / SOIC Package)

text
        ┌──────────┐
     A0 ─│ 1      8 │─ VCC
     A1 ─│ 2      7 │─ WP
     A2 ─│ 3      6 │─ SCL
    VSS ─│ 4      5 │─ SDA
        └──────────┘
PinNameDescription
1A0Hardware I2C Chip Address bit 0 input
2A1Hardware I2C Chip Address bit 1 input
3A2Hardware I2C Chip Address bit 2 input
4GND / VSSGround reference (0 V)
5SDAI2C Serial Data bidirectional line
6SCLI2C Serial Clock input line
7WPHardware Write Protect pin (High = Write Protect ON, Low/GND = Write Enable)
8VCCPositive power supply (+1.7V to +5.5V DC)

DS3231 RTC Module Address Conflict Resolution

On standard ZS-042 / DS3231 RTC breakout modules:

  • The DS3231 RTC IC uses fixed I2C address 0x68.
  • The onboard AT24C32 EEPROM IC has A0,A1,A2A_0, A_1, A_2 pulled HIGH by default, giving base I2C address 0x57 (1010111).
  • Bridging solder pads A0,A1,A2A_0, A_1, A_2 to GND changes the EEPROM address down to 0x50 (1010000), allowing multi-EEPROM bus designs.

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply Voltage RangeVCCV_{CC}1.73.3 / 5.05.5VOperational range
Read CurrentICC_READI_{CC\_READ}—4001000μA\mu\text{A}VCC=5.0V,fSCL=400kHzV_{CC} = 5.0\text{V}, f_{SCL} = 400\text{kHz}
Write CurrentICC_WRITEI_{CC\_WRITE}—1.03.0mAVCC=5.0VV_{CC} = 5.0\text{V}
Standby CurrentISBI_{SB}—1.06.0μA\mu\text{A}VCC=5.0V,I2C idleV_{CC} = 5.0\text{V}, I2C\text{ idle}
Write Cycle TimeTWRT_{WR}—2.05.0msSelf-timed page write

Common mistakes

  • Confusing 32-byte page size with 64-byte page size: The AT24C32 has a 32-byte page buffer (unlike 24LC256 which has a 64-byte page buffer). Writing more than 32 consecutive bytes without updating the page address wraps around within the 32-byte page window!
  • Forgetting 16-bit internal address bytes: EEPROMs with capacity >2048>2048 bytes (like AT24C32) require a 2-byte (16-bit) memory address to be transmitted over I2C before data bytes.

Notes

  • DS3231 Companion: Paired with the DS3231 RTC, the AT24C32 allows microcontrollers to log hourly timestamped temperature/event logs without relying on external SD card modules.

Assets & downloads