CAT5409WI25 ONSEMI [ON Semiconductor], CAT5409WI25 Datasheet - Page 7

• Manufacturer Part Number: CAT5409WI25
• Manufacturer: ONSEMI [ON Semiconductor]

WRITE OPERATIONS
In the
START condition and the slave address information to
the Slave device. After the Slave generates an
acknowledge, the Master sends the instruction byte
that defines the requested operation of CAT5409. The
instruction byte consist of a four-bit opcode followed
by two register selection bits and two pot selection
bits. After receiving another acknowledge from the
Slave, the Master device transmits the data to be
written into the selected register. The CAT5409
acknowledges once more and the Master generates
the STOP condition, at which time if a non-volatile
data register is being selected, the device begins an
internal programming cycle to non-volatile memory.
While this internal cycle is in progress, the device will
not respond to any request from the Master device.
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
Figure 5. Slave Address Bits
*
**
Figure 6. Write Timing
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Characteristics subject to change without notice
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.
Write mode, the Master device sends the
BUS ACTIVITY:
SDA LINE
MASTER
CAT5409
S
A
R
T
T
S
Fixed
SLAVE/DPP
ADDRESS
0
Variable
1
A
C
K
0
op code
INSTRUCTION
7
1
host's write operation, the CAT5409 initiates the
internal write cycle. ACK polling can be initiated
immediately. This involves issuing the start condition
followed by the slave address. If the CAT5409 is still
busy with the write operation, no ACK will be returned.
If the CAT5409 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
registers are protected and become read only.
Similarly, the WP
start will interrupt non-volatile write to data registers,
while the WP
has started, will have no effect on any write operation.
The CAT5409 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.
BYTE
A3
Register
Address
Pot/WCR
Address
A2
A
C
K
¯¯¯ pin going low after internal write cycle
DR1 WCRDATA
A1
¯¯¯ pin going low after start but after
A0
¯¯¯ pin is tied to LOW, the data
A
C
K
P
O
S
T
P
Doc. No. MD-2010 Rev. M
CAT5409