X9400 Datasheet, PDF (4/22 Pages) Xicor Inc. – Quad Digitally Controlled Potentiometers (XDCP)

X9400
Figure 1. Detailed Potentiometer Block Diagram
(One of Four Arrays)
Serial Data Path
From Interface
Circuitry
Register 0
8
Register 2
If WCR = 00[H] then V_W/R_W = V_L/R_L
If WCR = 3F[H] then V_W/R_W = V_H/R_H
Serial
Bus
Input
C
Register 1
o
u
6
Parallel
Bus
Input
n
t
e
r
Register 3
Wiper
Counter
D
Register
e
(WCR)
c
o
d
e
UP/DN
INC/DEC
Logic
UP/DN
Modified SCL
CLK
V_H/R_H
V_L/R_L
V_W/R_W
Write in Process
The contents of the Data Registers are saved to
nonvolatile memory when the CS pin goes from LOW
to HIGH after a complete write sequence is received by
the device. The progress of this internal write operation
can be monitored by a write in process bit (WIP). The
WIP bit is read with a read status command.
INSTRUCTIONS
required for the X9400 to successfully continue the
command sequence. The A₀–A₁ inputs can be actively
driven by CMOS input signals or tied to V_CC or V_SS.
The remaining two bits in the slave byte must be set to 0.
Figure 2. Identification Byte Format
Device Type
Identifier
Identification (ID) Byte
The first byte sent to the X9400 from the host, following
a CS going HIGH to LOW, is called the Identification
byte. The most significant four bits of the slave address
are a device type identifier, for the X9400 this is fixed
as 0101[B] (refer to Figure 2).
The two least significant bits in the ID byte select one of
four devices on the bus. The physical device address is
defined by the state of the A₀-A₁ input pins. The X9400
compares the serial data stream with the address input
state; a successful compare of both address bits is
0 1 0 1 0 0 A1 A0
Device Address
Instruction Byte
The next byte sent to the X9400 contains the
instruction and register pointer information. The four
most significant bits are the instruction. The next four
bits point to one of the four pots and, when applicable,
they point to one of four associated registers. The
format is shown below in Figure 3.
REV 1.1.4 10/11/02
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Characteristics subject to change without notice. 4 of 22