CAT1021LI-25-G(2009) データシートの表示（PDF） - ON Semiconductor

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CAT1021LI-25-G
(Rev.:2009)

Supervisory Circuits with I2C Serial 2k-bit CMOS EEPROM, Manual Reset and Watchdog Timer

ON Semiconductor 

CAT1021, CAT1022, CAT1023

ACKNOWLEDGE

After a successful data transfer, each receiving

device is required to generate an acknowledge. The

acknowledging device pulls down the SDA line

during the ninth clock cycle, signaling that it received

the 8 bits of data.

All devices respond with an acknowledge after

receiving a START condition and its slave address.

If the device has been selected along with a write

operation, it responds with an acknowledge after

receiving each 8-bit byte.

When a device begins a READ mode it transmits 8

bits of data, releases the SDA line and monitors the

line for an acknowledge. Once it receives this

acknowledge, the device will continue to transmit

data. If no acknowledge is sent by the Master, the

device terminates data transmission and waits for a

STOP condition.

WRITE OPERATIONS

Byte Write

In the Byte Write mode, the Master device sends the

START condition and the slave address information

(with the R/¯W¯ bit set to zero) to the Slave device. After

the Slave generates an acknowledge, the Master sends

a 8-bit address that is to be written into the address

pointers of the device. After receiving another acknow-

ledge from the Slave, the Master device transmits the

data to be written into the addressed memory location.

The device acknowledges once more and the Master

generates the STOP condition. At this time, the device

begins an internal programming cycle to non-volatile

memory. While the cycle is in progress, the device will

not respond to any request from the Master device.

Figure 5. Start/Stop Timing

SDA

SCL

START BIT

Figure 6. Acknowledge Timing

STOP BIT

SCL FROM

1

MASTER

8

9

DATA OUTPUT

FROM TRANSMITTER

DATA OUTPUT

FROM RECEIVER

START

ACKNOWLEDGE

Figure 7: Slave Address Bits

Default Configuration 1

0

1

0

0

0

0 R/W

Doc. No. MD-3009 Rev. P

10

© 2009 SCILLC. All rights reserved.

Characteristics subject to change without notice

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