CAT5113

http://onsemi.com

3

Functional Diagram

Figure 1. General

Control

and

Memory

Power On

GND

Decoder

31

30

29

28

2

1

0

Transfer

Gates

Resistor

Array

5−Bit

Nonvolatile

Memory

Store and

Recall

Control

Circuitry

5−Bit

Up/Down

Counter

GND

Figure 2. Detailed

Figure 3. Electronic

Potentiometer

Implementation

CS

INC

U/D

Recall

CS

INC

U/D

1 of 32

Pin Description

INC: Increment Control Input

The INC input moves the wiper in the up or down direction

determined by the condition of the U/D input.

U/D: Up/Down Control Input

The U/D input controls the direction of the wiper movement.

When in a high state and CS is low, any high−to−low

transition on INC will cause the wiper to move one

CS is low, any high-to-low transition on INC will cause the

required that this terminal be connected to a potential greater

GND.

the resistor array is controlled by the control inputs, INC,

required that this terminal be connected to a potential less

CS: Chip Select

The chip select input is used to activate the control input of

the CAT5113 and is active low. When in a high state, activity

on the INC and U/D inputs will not affect or change the

position of the wiper.

Device Operation

The CAT5113 operates like a digitally controlled

potentiometer’s wiper. There are 100 available tap positions

terminals. The wiper terminal is connected to one of the 100

taps and controlled by three inputs, INC, U/D and CS. These

inputs control a seven−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 CAT5113 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 seven-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 CAT5113 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 CAT5113 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.