7

CAT5269

Document No. 2123, Rev. B

ACKNOWLEDGE

1

START

SCL FROM

MASTER

89

DATA OUTPUT

FROM TRANSMITTER

DATA OUTPUT

FROM RECEIVER

Figure 4. Acknowledge Condition

Acknowledge Polling

The disabling of the inputs can be used to take advantage

of the typical write cycle time. Once the stop condition is

issued to indicate the end of the host's write operation,

the CAT5269 initiates the internal write cycle. ACK

polling can be initiated immediately. This involves issuing

the start condition followed by the slave address. If the

CAT5269 is still busy with the write operation, no ACK

will be returned. If the CAT5269 has completed the write

operation, an ACK will be returned and the host can then

proceed with the next instruction operation.

WRITE PROTECTION

The Write Protection feature allows the user to protect

against inadvertent programming of the non-volatile

data registers. If the

WP pin is tied to LOW, the data

registers are protected and become read only. Similarly,

the

WP pin going low after start will interrupt a non-

volatile write to data registers, while the

WP pin going

low after an internal write cycle has stated will have no

effect on any write operation (see also CAT5409 or

CAT5259). The CAT5269 will accept both slave

addresses and instructions, but the data registers are

protected from programming by the device’s failure to

send an acknowledge after data is received.

Figure 5. Slave Address Bits

0

1

0

1

A3A2A1

A0

CAT5269

*

A0, A1, A2 and A3 correspond to pin A0, A1, A2 and A3 of the device.

**

A0, A1, A2 and A3 must compare to its corresponding hard wired input pins.

Figure 3. Start/Stop Condition

START CONDITION

SDA

STOP CONDITION

SCL