6

FN8181.2

February 19, 2008

position in nonvolatile memory. After the wiper movement is

performed as previously described and once the new

position is reached, the system must keep INC LOW while

taking CS HIGH. The new wiper position will be maintained

until changed by the system or until a power-up/down cycle

recalled the previously stored data. In order to recall the

stored position of the wiper on power-up, the CS pin must be

held HIGH.

This procedure allows the system to always power-up to a

preset value stored in nonvolatile memory; then during

system operation, minor adjustments could be made. The

adjustments might be based on user preference, system

parameter changes due to temperature drift, or other system

trim requirements.

The state of U/D may be changed while CS remains LOW.

This allows the host system to enable the device and then

move the wiper up and down until the proper trim is attained.

Symbol Table

Applications Information

Electronic digitally controlled (XDCP) potentiometers provide

three powerful application advantages:

1. The variability and reliability of a solid-state potentiometer

2. The flexibility of computer-based digital controls

3. The retentivity of nonvolatile memory used for the storage

of multiple potentiometer settings or data

Mode Selection

CS

INC

U/D

MODE

L

H

Wiper Up

L

L

Wiper Down

H

X

Store Wiper Position

H

X

X

Standby Current

L

X

No Store, Return to Standby

L

H

Wiper Up (not recommended)

L

L

Wiper Down (not recommended)

WAVEFORM

INPUTS

OUTPUTS

Must be

steady

Will be

steady

May change

from Low to

High

Will change

from Low to

High

May change

from High to

Low

Will change

from High to

Low

Don’t Care:

Changes

Allowed

Changing:

State Not

Known

N/A

Center Line

is High

Impedance

Two terminal variable resistor.

I

X93155