at24c04c-xhm-t ATMEL Corporation, at24c04c-xhm-t Datasheet - Page 6

• Manufacturer Part Number: at24c04c-xhm-t
• Description: I 2 C-compatible 2-wire Serial Eeprom
• Manufacturer: ATMEL Corporation

3.
Device Operation
CLOCK and DATA TRANSITIONS: The SDA pin is normally pulled high with an external device. Data on the SDA
pin may change only during SCL low time periods (see
Figure 5-2 on page
8). Data changes during SCL high
periods will indicate a start or stop condition as defined below.
START CONDITION: A high-to-low transition of SDA with SCL high is a start condition which must precede any
other command (see
Figure 5-3 on page
8).
STOP CONDITION: A low-to-high transition of SDA with SCL high is a stop condition. After a read sequence, the
stop command will place the EEPROM in a standby power mode (see
Figure 5-3 on page
8).
ACKNOWLEDGE: All addresses and data words are serially transmitted to and from the EEPROM in 8-bit words.
The EEPROM sends a zero to acknowledge that it has received each word. This happens during the ninth clock
cycle.
STANDBY MODE: The Atmel AT24C04/08C features a low-power standby mode which is enabled: (a) upon
power-up and (b) after the receipt of the STOP bit and the completion of any internal operations.
2-WIRE SOFTWARE RESET: After an interruption in protocol, power loss or system reset, any 2-wire part can be
reset by following these steps: (a) Create a start bit condition, (b) clock nine cycles, (c) create another start bit
followed by stop bit condition as shown below. The device is ready for next communication after above steps have
been completed.
Figure 3-1.
Software reset
Dummy Clock Cycles
SCL
1
2
3
8
9
Start
Stop
Start
Bit
Bit
Bit
SDA
Atmel AT24C04C/08C [PRELIMINARY]
6
8787A–SEEPR–10/11