x9455wp24i Intersil Corporation, x9455wp24i Datasheet - Page 12

• Manufacturer Part Number: x9455wp24i
• Description: Dual Two-wiper Digitally-controlled Xdcp? Potentiometer
• Manufacturer: Intersil Corporation

Slave Address Byte
Following a START condition, the master must output a
Slave Address Byte (Refer to figure 4.). This byte includes
three parts:
• The four MSBs (SA7-SA4) are the Device Type Identifier,
• The next three bits (SA3-SA1) are the Device Address bits
• The LSB (SA0) is the R/W bit. This bit defines the
Nonvolatile Write Acknowledge Polling
After a nonvolatile write command sequence is correctly
issued (including the final STOP condition), the X9455
initiates an internal high voltage write cycle. This cycle
typically requires 5 ms. During this time, any Read or Write
command is ignored by the X9455. Write Acknowledge
Polling is used to determine whether a high voltage write
cycle is completed.
During acknowledge polling, the master first issues a START
condition followed by a Slave Address Byte. The Slave
Address Byte contains the X9455’s Device Type Identifier
and Device Address. The LSB of the Slave Address (R/W)
can be set to either 1 or 0 in this case. If the device is busy
within the high voltage cycle, then no ACK is returned. If the
high voltage cycle is completed, an ACK is returned and the
master can then proceed with a new Read or Write
operation. (Refer to figure 5.)
which must always be set to 0101 in order to select the
X9455.
(AS2-AS0). To access any part of the X9455’s memory,
the value of bits AS2, AS1, and AS0 must correspond to
the logic levels at pins A2, A1, and A0 respectively.
operation to be performed on the device being addressed.
When the R/W bit is “1”, then a Read operation is
selected. A “0” selects a Write operation
SLAVE ADDRESS
SA7
0
SA7-SA4
SA3-SA1
BIT(S)
FIGURE 4. SLAVE ADDRESS (SA) FORMAT
Device Type
SA0
SA6
Identifier
1
SA5
0
Device Type Identifier
Device Address
Read or Write Operation Select
SA4
1
12
AS2
SA3
DESCRIPTION
Address
Device
SA2
AS1
AS0
SA1
.
Read or
Write
R/W
SA0
X9455
2-Wire Serial Interface Operation
X9455 Digital Potentiometer Register Organization
Refer to the Functional Diagram on page 1. There are 2
Digital Potentiometers, referred to as DCP0, and DCP1.
Each potentiometer has two volatile Wiper Control Registers
(WCRs). Each wiper has four non-volatile registers to store
wiper position or general data. See Table 2 for register
numbering.
FIGURE 5. ACKNOWLEDGE POLLING SEQUENCE
complete. Continue command
Continue normal Read or Write
Issue Slave Address
Byte (Read or Write)
Issue START
ACK returned?
Byte load completed by issuing
command sequence
High Voltage
sequence.
STOP. Enter ACK Polling
PROCEED
YES
YES
NO
Issue STOP
NO
Issue STOP
July 28, 2006
FN8202.1