X9110_08 INTERSIL [Intersil Corporation], X9110_08 Datasheet - Page 4
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X9110_08
Manufacturer Part Number
X9110_08
Description
Dual Supply/Low Power/1024-Tap/SPI Bus
Manufacturer
INTERSIL [Intersil Corporation]
Datasheet
1.X9110_08.pdf
(18 pages)
Potentiometer Pins
R
The R
connections on a mechanical potentiometer.
R
The wiper pin are equivalent to the wiper terminal of a
mechanical potentiometer.
Bias Supply Pins
SYSTEM SUPPLY VOLTAGE (V
GROUND (V
The V
the system ground.
ANALOG SUPPLY VOLTAGES (V+ AND V
These supplies are the analog voltage supplies for the
potentiometer. The V+ supply is tied to the wiper switches
while the V- supply is used to bias the switches and the
internal P+ substrate of the integrated circuit. Both of these
supplies set the voltage limits of the potentiometer.
Principles Of Operation
Device Description
SERIAL INTERFACE
The X9110 supports the SPI interface hardware conventions.
The device is accessed via the SI input with data clocked-in
H
W
If WCR = 000[HEX] then R
If WCR = 3FF[HEX] then R
, R
L
CC
H
FROM INTERFACE
SERIAL DATA PATH
and R
CIRCUITRY
pin is the system supply voltage. The V
SS
L
)
pins are equivalent to the terminal
W
W
= R
= R
4
L
REGISTER 0
REGISTER 2
H
CC
(DR0)
(DR2)
) AND SUPPLY
FIGURE 1. DETAILED POTENTIOMETER BLOCK DIAGRAM
-
)
10
SS
pin is
REGISTER 1
REGISTER 3
(DR1)
(DR3)
X9110
10
on the rising SCK. CS must be LOW and the HOLD and WP
pins must be HIGH during the entire operation.
The SO and SI pins can be connected together, since they
have three state outputs. This can help to reduce system pin
count.
ARRAY DESCRIPTION
The X9110 is comprised of a resistor array (Figure 1). The
array contains the equivalent of 1023 discrete resistive
segments that are connected in series. The physical ends of
each array are equivalent to the fixed terminals of a
mechanical potentiometer (R
At both ends of each array and between each resistor
segment is a CMOS switch connected to the wiper (R
output. Within the individual array only one switch may be
turned on at a time.
These switches are controlled by a Wiper Counter Register
(WCR). The 10-bits of the WCR (WCR[9:0]) are decoded to
select, and enable, one of 1024 switches.
WIPER COUNTER REGISTER (WCR)
The X9110 contains a Wiper Counter Register (see Table 1)
for the XDCP potentiometer. The WCR is equivalent to a
serial-in, parallel-out register/counter with its outputs
decoded to select one of 1024 switches along its resistor
array. The contents of the WCR can be altered in one of
three ways: (1) it may be written directly by the host via the
write Wiper Counter Register instruction (serial load); (2) it
BUS
INPUT
SERIAL
BUS
INPUT
PARALLEL
REGISTER
COUNTER
WIPER
(WCR)
C
O
U
N
T
E
R
D
E
C
O
D
E
H
and R
L
inputs).
R H
R L
R
W
February 13, 2008
W
FN8158.3
)