CAT5133 Datasheet, PDF (2/9 Pages) Catalyst Semiconductor – 16 Volt Digitally Programmable Potentiometer (DPP TM) with 128 Taps and an Increment Decrement Interface

CAT5133
V_CC
V+
UP/DOWN
(U/D)
Increment
(INC)
Control Logic and
Address Decode
127
R_H
Device Select
(CS)
128 Tap Position
Decode Control
7−Bit
Nonvolatile
7−Bit Wiper
Memory
Control
Register
Register
(DR)
(WCR)
0
R_L
Figure 1. Block Diagram
R_W
Table 1. PIN DESCRIPTIONS
Pin
Name
Function
1
U/D
Up/Down Data Input – Determines the direction of movement of the wiper
2
GND
Ground
3
V_CC
Logic Supply Voltage (2.7 V to 5.5 V)
4
CS
Chip Select − The chip is selected when the input is low.
5
N/C
No Connect
6
R_H
High Reference Terminal for the Potentiometer
7
R_W
Wiper Terminal for the Potentiometer
8
R_L
Low Reference Terminal for the Potentiometer
9
V₊
Analog Bias Voltage Input (+8.0 V to +16.0 V)
10
INC
Increment Input – Moves the wiper in the direction determined by the Up/Down input on each negative edge
Device Operation
The CAT5133 operates like a digitally controlled
potentiometer with R_H and R_L equivalent to the high and low
terminals and R_W equivalent to the mechanical
potentiometer’s wiper. There are 128 available tap positions
including the resistor end points, R_H and R_L. There are 127
resistor elements connected in series between the R_H and R_L
terminals. The wiper terminal is connected to one of the 128
taps and controlled by three inputs, INC, U/D and CS. These
inputs control a 7-bit up/down counter whose output is
decoded to select the wiper position. The selected wiper
position can be stored in nonvolatile memory using the INC
and CS inputs.
With CS set LOW the CAT5133 is selected and will
respond to the U/D and INC inputs. HIGH to LOW
transitions on INC will increment or decrement the wiper
(depending on the state of the U/D input and 7-bit counter).
The wiper, when at either fixed terminal, acts like its
mechanical equivalent and does not move beyond the last
position. The value of the counter is stored in nonvolatile
memory whenever CS transitions HIGH while the INC input
is also HIGH. When the CAT5133 is powered-down; the last
stored wiper counter position is maintained in the
nonvolatile memory. When power is restored, the contents
of the memory are recalled and the counter is set to the value
stored.
With INC set low, the CAT5133 may be de-selected and
powered down without storing the current wiper position in
nonvolatile memory. This allows the system to always
power up to a preset value stored in nonvolatile memory.
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