7 of 10

REV 1.7 7/10/03

www.xicor.com

X9319

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) the seven 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 nonvolatile mem-

ory whenever CS transitions HIGH while the INC input

is also HIGH.

The system may select the X9319, move the wiper and

deselect the device without having to store the latest

wiper position in nonvolatile memory. After the wiper

movement is performed as described above 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 powerup/down cycle recalled the previously stored

data. This procedure allows the system to always

power-up to a preset value stored in nonvolatile mem-

ory; then during system operation minor adjustments

could be made. The adjustments might be based on

user preference, 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.

MODE SELECTION

CS

INC

U/D

Mode

L

H

Wiper up

L

L

Wiper down

HX

Store wiper position to

nonvolatile memory

H

X

X

Standby

L

X

No store, return to standby

L

H

Wiper Up (not recommended)

LL

Wiper Down

(not recommended)