CAT5269 Datasheet, PDF (7/15 Pages) Catalyst Semiconductor – Dual Digitally Programmable Potentiometers (DPP) with 256 Taps and 2-wire Interface

CAT5269
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 3. Start/Stop Condition
SDA
SCL
START CONDITION
Figure 4. Acknowledge Condition
SCL FROM
1
MASTER
STOP CONDITION
8
9
DATA OUTPUT
FROM TRANSMITTER
DATA OUTPUT
FROM RECEIVER
START
Figure 5. Slave Address Bits
ACKNOWLEDGE
CAT5269 0 1 0 1 A3 A2 A1 A0
* 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.
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Document No. 2123, Rev. B