X9C102, X9C103, X9C104, X9C503

FN8222 Rev 3.00

Page 7 of 10

July 20, 2009

Instructions and Programming

The INC, U/D and CS inputs control the movement of the wiper

along the resistor array. With CS set LOW, the device is selected

and enabled to respond to the U/D and INC inputs. HIGH to

LOW transitions on INC will increment or decrement (depending

on the state of the U/D input) a 7-bit counter. The output of this

counter is decoded to select one of one-hundred wiper positions

along the resistive array.

The value of the counter is stored in non-volatile memory

whenever CS transitions HIGH while the INC input is also

HIGH.

The system may select the X9Cxxx, move the wiper and

deselect the device without having to store the latest wiper

position in non-volatile 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-down/up cycle recalled the

previously stored data.

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

set value stored in non-volatile memory; then during system

operation, minor adjustments could be made. The adjustments

might be based on user preference, i.e.: system parameter

changes due to temperature drift, etc.

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

Performance Characteristics

Contact the factory for more information.

Applications Information

Electronic digitally controlled (XCDP) 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 non-volatile 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