AT24C128_07 Datasheet, PDF (6/17 Pages) ATMEL Corporation – Two-wire Automotive Temperature Serial EEPROMs

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 4 on
page 7). 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 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 Fig-
ure 5 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 during the ninth clock cycle to acknowl-
edge that it has received each word.
STANDBY MODE: The AT24C128/256 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.
MEMORY RESET: After an interruption in protocol, power loss or system reset, any two-wire
part can be reset by following these steps: (a) Clock up to 9 cycles, (b) look for SDA high in
each cycle while SCL is high and then (c) create a start condition as SDA is high.
6 AT24C128/256
5121B–SEEPR–2/07