X9522_06 Datasheet, PDF (5/27 Pages) Intersil Corporation – Triple DCP, Dual Voltage Monitors

X9522
SCL
from
1
Master
Data Output
from
Transmitter
8
9
Data Output
from
Receiver
Start
Acknowledge
Figure 3. Acknowledge Response From Receiver
DEVICE INTERNAL ADDRESSING
Addressing Protocol Overview
The user addressable internal components of the X9522
can be split up into two main parts:
—Three Digitally Controlled Potentiometers (DCPs)
—Control and Status (CONSTAT) Register
Depending upon the operation to be performed on
each of these individual parts, a 1, 2 or 3 Byte proto-
col is used. All operations however must begin with
the Slave Address Byte being issued on the SDA pin.
The Slave address selects the part of the X9522 to
be addressed, and specifies if a Read or Write opera-
tion is to be performed.
It should be noted that in order to perform a write opera-
tion to a DCP, the Write Enable Latch (WEL) bit must first
be set.
Slave Address Byte
Following a START condition, the master must output a
Slave Address Byte (Refer to Figure 4.). This byte con-
sists of three parts:
—The Device Type Identifier which consists of the most
significant four bits of the Slave Address (SA7 - SA4).
The Device Type Identifier must always be set to 1010
in order to select the X9522.
—The next three bits (SA3 - SA1) are the Internal Device
Address bits. Setting these bits to 111 internally
selects the DCP structures in the X9522. The CON-
STAT Register may be selected using the Internal
Device Address 010.All other bit combinations are
RESERVED.
—The Least Significant Bit of the Slave Address (SA0)
Byte is the R/W bit. This bit defines the operation to be
performed on the device being addressed (as defined
in the bits SA3 - SA1). When the R/W bit is “1”, then a
READ operation is selected. A “0” selects a WRITE
operation (Refer to Figure 4.)
SA7 SA6 SA5 SA4 SA3 SA2 _{SA1 SA0}
101 0
R/W
DEVICE TYPE
IDENTIFIER
INTERNAL
DEVICE
ADDRESS
READ /
WRITE
Internal Address
(SA3 - SA1)
010
111
Others
Internally Addressed
Device
CONSTAT Register
DCP
RESERVED
Bit SA0
0
1
Operation
WRITE
READ
Figure 4. Slave Address Format
5
FN8208.1
January 3, 2006