cat5132 Catalyst Semiconductor, cat5132 Datasheet - Page 11

• Manufacturer Part Number: cat5132
• Description: 16 Volt Digitally Programmable Potentiometer Dpp? With 128 Taps And I?c Interface
• Manufacturer: Catalyst Semiconductor

POTENTIOMETER OPERATION
Power-On
The CAT5132 is a 128-position, digital controlled
potentiometer. When applying power to the CAT5132,
V
At the sametime, the signals on R
should not exceed V+. If V+ is applied before V
electronic switches of the DPP are powered in the
absence of the switch control signals, that could result in
multiple switches being turned on. This causes
unexpected wiper settings and possible current overload
of the potentiometer. When V
turns on at the mid-point wiper location (64) until the
wiper register can be loaded with the nonvolatile memory
location previously stored in the device. After the
nonvolatile memory data is loaded into the wiper register
the wiper location will change to the previously stored
wiper position.
At power-down, it is recommended to turn-off first the
signals on R
V
wipper and uncontrolled current overload of the
potentiometer.
The end-to-end nominal resistance of the potentiometer
has 128 contact points linearly distributed across the
total resistor. Each of these contact points is addressed
by the 7 bit wiper register which is decoded to select one
of these 128 contact points.
Each contact point generates a linear resistive value
between the 0 position and the 127 position. These
values can be determined by dividing the end-to-end
value of the potentiometer by 127. In the case of the
© Catalyst Semiconductor, Inc.
Characteristics subject to change without notice
CC
CC
, in order to avoid unexpected transmistions of the
must be suplied prior to or simultaneously with V+.
H
, R
W
and R
L
, followed by V+ and, after that,
CC
H
is applied the device
, R
W
and R
L
terminals
CC
, The
11
10k
each wiper position. However in addition to the ~79 for
each resistive segment of the potentiometer, a wiper
resistance offset must be considered. Table 8 shows the
effect of this value and how it would appear on the wiper
terminal.
This offset will appear in each of the CAT5132 end-to-
end resistance values in the same way as the 10k
example. However resistance between each wiper
position for the 50k version will be ~395 and for the
100k version will be ~790 .
Table 8. Potentiometer Resistance and Wiper
Resistance Offset Effects
P
P
o
o
1
1
1
s
s
0
0
6
6
0
2
2
2
t i
t i
0
3
0
4
1
potentiometer ~79
7
6
7
o i
o i
n
n
T
T
y
y
1
1
p
p
5
0
0
5
c i
c i
0 ,
0 ,
0 ,
0 ,
1
1
l a
l a
7
4
4
7
7
4
4
7
0
9
7
0
0
7
9
0
R
R
W
W
1
1
r o
r o
r o
r o
r o
r o
r o
r o
is the resistance between
o t
o t
0
0
k
k
R
R
H
L
D
D
R
R
P
P
e
e
s
P
s
P
1
1
s i
s i
Doc No. MD-2124, Rev. E
4
0
0
4
a t
a t
9 ,
0 ,
0 ,
9 ,
CAT5132
n
n
7
7
0
0
7
7
c
0
9
7
0
c
0
7
9
0
e
e
f
f
r o
+
+
+
+
+
+
+
+
r o
7
7
7
7
7
7
7
7
0
0
0
0
0
0
0
0