8

Atmel AT24MAC402/602 [DATASHEET]

8807A–SEEPR–6/12

4.

Device Operation

Clock and Data Transitions: The SDA pin is normally pulled high with an external component such as a pull-up resistor.

Data on the SDA pin may change only during SCL low time periods (see Figure 4-4 on page 9). 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 4-5 on page 9).

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 4-5 on page 9).

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 AT24MAC402/602 features a low-power standby mode which is enabled upon



Power-up or



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:

1.

Create a start bit condition.

2.

Clock nine cycles.

3.

Create another start bit followed by Stop bit condition as shown below.

Figure 4-1. Software Reset

Figure 4-2. Bus Timing

SCL Serial Clock, SDA: Serial Data I/O

SCL

9

Start

Bit

Start

Bit

Stop

Bit

8

3

2

1

SDA

Dummy Clock Cycles

SCL

SDA IN

SDA OUT