OMO ElectronicOMO Electronic
Expand menu
Hello, Sign inMy Account
0 Cart

CAT5120SDI-50GT3

P1-P3P4-P6P7-P9P10-P11
CAT5120, CAT5121, CAT5122
http://onsemi.com
4
TYPICAL OPERATING CHARACTERISTICS
(T
A
= 25C, unless otherwise noted.)
Figure 2. Wiper Resistance vs. Tap Position Figure 3. Change in End-to-End Resistance vs.
Temperature
WIPER POSITION TEMPERATURE (C)
28 32201612840
0
50
100
150
200
250
150100500−50
−2.0
−1.5
−1.0
−0.5
0
0.5
1.0
1.5
Figure 4. W-to-L Resistance vs. Tap Position Figure 5. Supply Current vs. Temperature
TAP POSITION TEMPERATURE (C)
317531
0
20
60
80
100
120
Figure 6. Tap-to-Tap Switching Transient
WIPER RESISTANCE (W)
END−TO−END RESISTANCE
CHANGE (%)
RESISTANCE (kW)
24
V
DD
= 2.7 V
V
DD
= 5.5 V
50 K
40
150100500−50
0
0.05
0.10
0.20
0.25
0.30
0.40
0.45
CURRENT (mA)
0.15
0.35
V
DD
= 2.7 V
V
DD
= 5.5 V
13119191715 252321 2927
100 k
50 k
10 k
200 ns/div
U/D
2 V/div
Wiper
Output
100 mV/div
CAT5120, CAT5121, CAT5122
http://onsemi.com
5
FUNCTIONAL DESCRIPTION
The CAT5120/5121/5122 consist of a fixed resistor and a
wiper contact with 16-tap points that are digitally controlled
through a 2-wire up/down serial interface. Two end-to-end
resistance values are available: 10 kW and 50 kW.
The CAT5120 is designed to operate as a potentiometer.
In this configuration, the low terminal of the resistor array
is connected to ground (pin 2).
The CAT5122 performs as a variable resistor. In this
device, the wiper terminal and high terminal of the resistor
array is connected at pin 5. The CAT5121 is a similar
variable resistor, except the low terminal is connected to
pin 5.
Digital Interface Operation
The devices have two modes of operation when the serial
interface is active: increment and decrement mode. The
serial interface is only active when CS
is low.
The CS
and U/D inputs control the position of the wiper
along the resistor array. When CS
transitions from high to
low, the part will go into increment mode if U/D
input is
high, and into decrement mode when U/D
input is low. Once
the mode is set, the device will remain in that mode until CS
goes high again. A low-to-high transition at the U/D pin will
increment or decrement the wiper position depending on the
current mode (Figures 7 and 8).
When the CS
input transitions to high (serial interface
inactive), the value of the counter is stored and the wiper
position is maintained.
Note that when the wiper reaches the maximum (or
minimum) tap position, the wiper will not wrap around to the
minimum (or maximum) position.
Power-on Reset
All parts in this family feature power-on reset (POR)
circuitry that sets the wiper position to midscale at
power-up. By default, the chip is in the increment mode.
Figure 7. Serial Interface Timing Diagram, Increment Mode
W
t
CU
U/D
CS
t
CI
t
IL
t
IH
t
SETTLE
t
SETTLE
t
IC
Note: “W” is not a digital signal. It represents wiper transitions.
Figure 8. Serial Interface Timing Diagram, Decrement Mode
W
Note: “W” is not a digital signal. It represents wiper transitions.
U/D
CS
t
CU
t
CI
t
SETTLE
t
IH
t
IL
t
IC
t
SETTLE
CAT5120, CAT5121, CAT5122
http://onsemi.com
6
APPLICATIONS INFORMATION
The devices are intended for circuits requiring digitally
controlled adjustable resistance, such as LCD contrast
control, where voltage biasing adjusts the display contrast.
Alternative Positive LCD Bias Control
Use an op amp to provide buffering and gain on the output
of the CAT5120. Connect the mechanical potentiometer to
the positive input of a noninverting op amp (Figure 9) to
select a portion of the input signal by digitally controlling the
wiper terminal. Figure 10 shows a similar circuit for the
CAT5121.
Adjustable Gain
Figures 11 and 12 show how to use the variable resistor to
digitally adjust the gain of a noninverting op amp
configuration. Connect the CAT5121 in series with a resistor
to ground to form the adjustable gain control of a
noninverting amplifier. The devices have a low 5 ppm/C
ratiometric tempco that allows for a very stable adjustable
gain configuration over temperature.
30 V
W
L
H
+5 V
30 V
L
H
+5 V
L
H
L
H
W
CAT5120
CAT5121
CAT5121
CAT5120
Figure 9. Positive LCD Bias Control Figure 10. Positive LCD Bias Control
Figure 11. Adjustable Gain Circuit Figure 12. Adjustable Gain Circuit
V
OUT
V
OUT
V
IN
V
CC
V
OUT
V
IN
V
OUT
V
CC
P1-P3P4-P6P7-P9P10-P11

CAT5120SDI-50GT3

Mfr. #:
Buy CAT5120SDI-50GT3
Manufacturer:
ON Semiconductor
Description:
Digital Potentiometer ICs DPP MINIPOT 16 TAPS U/D
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union

Products related to this Datasheet