x9440 Intersil Corporation, x9440 Datasheet - Page 3

• Manufacturer Part Number: x9440
• Description: Mixed Signal With Spi Interface
• Manufacturer: Intersil Corporation

PIN CONFIGURATION
PIN NAMES
V
OUT0,
V
V
V
Symbol
V
S1, SO
NI0
W0
A0-A1
H0
V+,V-
L0
SCK
V
V
WP
NC
-V
–V
, V
CC
SS
-V
V
H1
L1
OUT1
W1
NI1
V
HOLD
,
OUT1
V
V
V
SCK
V
V
V
V
V
V
WP
V
V
V
V
CS
CC
W0
A1
W1
NC
NI1
H0
H1
SS
W1
A1
L0
SI
L1
SS
H1
SI
L1
V-
Serial Clock
Serial Data
Device Address
Potentiometers (terminal equivalent)
Potentiometers (wiper equivalent)
Comparator Input Voltages
Buffered Comparator Outputs
Hardware Write Protection
Analog and Voltage Comparator
Supplies
System Supply Voltage
System Ground
No Connection
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
X9440
X9440
TSSOP
SOIC
3
Description
24
23
22
21
20
19
18
17
16
15
14
13
24
23
22
21
20
19
18
17
16
15
14
13
V+
V
V
NC
A0
SO
HOLD
SCK
NC
V
V
V-
V+
V
V
S0
WP
V
V
V
V
NC
A0
CS
OUT0
NI0
NI1
OUT1
OUT0
NI0
W0
H0
L0
CC
X9440
PRINCIPLES OF OPERATION
The X9440 is a highly integrated microcircuit incorpo-
rating two resistor arrays, two voltage comparators
and their associated registers and counters; and the
serial interface logic providing direct communication
between the host and the digitally-controlled potenti-
ometers and voltage comparators.
Serial Interface
The X9440 supports the SPI interface hardware con-
ventions. The device is accessed via the SI input with
data clocked in 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 X9440 is comprised of two resistor arrays and two
voltage comparators. Each array contains 63 discrete
resistive segments that are connected in series. The
physical ends of each array are equivalent to the fixed
terminals of a mechanical potentiometer (V
inputs).
At both ends of each array and between each resistor
segment is a CMOS switch connected to the wiper
(V
switch may be turned on at a time. These switches are
controlled by a volatile wiper counter register (WCR).
The six bits of the WCR are decoded to select, and
enable, one of sixty-four switches.
The WCR may be written directly, or it can be changed
by transferring the contents of one of four associated
data registers into the WCR. These data registers and
the WCR can be read and written by the host system.
Voltage Comparator
The comparator compares the wiper voltage V
the external input voltage V
logic level output are controlled by the shutdown,
latch, and enable bits of the analog control register
(ACR). Enable connects the comparator output to the
V
shutdown removes the analog section supply voltages
to save power. The analog control register (ACR) is
programmed using the SPI serial interface.
The ACR may be written directly, or it can be changed
by transferring the contents of one of four associated
data registers into the ACR. These data registers and
the ACR may be read and written by the host system.
OUT
W
) output. Within each individual array only one
pin, Latch memorizes the output logic state, and
NI
. The comparator and its
March 28, 2005
H
and V
W
FN8200.0
with
L