at24c64b ATMEL Corporation, at24c64b Datasheet - Page 5

• Manufacturer Part Number: at24c64b
• Description: 2-wire Serial Eeprom 64k 8192 X 8
• Manufacturer: ATMEL Corporation

5. Device Operation
3350E–SEEPR–9/07
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 (refer to Data Valid-
ity timing diagram). 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 (refer to Start and Stop Definition timing diagram).
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 (refer to
Start and Stop Definition timing diagram).
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 AT24C64B 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 2-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.
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