ISL95310

FN8083 Rev 1.00

Page 6 of 9

August 27, 2015

A.C. Timing

Power Up and Down Requirements

In order to prevent unwanted tap position changes, or an

inadvertent store, bring the CS and INC high before or

potentiometer voltages must be applied after this sequence

is completed. During power-up, the data sheet parameters

Pin Descriptions

equivalent to the fixed terminals of a mechanical

relative position of the terminal in relation to wiper movement

direction selected by the U/D input and not the voltage

potential on the terminal.

R

W

terminal of a mechanical potentiometer. The position of the

wiper within the array is determined by the control inputs.

Up/Down (U/D)

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

and whether the counter is decremented.

Increment (INC)

The INC input is negative-edge triggered. Toggling INC will

move the wiper and either increment or decrement the

counter in the direction indicated by the logic level on the

U/D input.

Chip Select (CS)

The device is selected when the CS input is LOW. The

current counter value is stored in nonvolatile memory when

CS is returned HIGH while the INC input is also HIGH. After

the store operation is complete the ISL95310 will be placed

in the low power standby mode until the device is selected

once again.

Principles of Operation

There are three sections of the ISL95310: the input control,

counter and decode section; the nonvolatile memory; and

the resistor array. The input control section operates just like

an up/down counter. The output of this counter is decoded to

turn on a single electronic switch connecting a point on the

resistor array to the wiper output. Under the proper

conditions the contents of the counter can be stored in

nonvolatile memory and retained for future use. The resistor

array is comprised of 127 individual resistors connected in

series. At either end of the array and between each resistor

is an electronic switch that transfers the potential at that

point to the wiper.

The wiper, when at either fixed terminal, acts like its

mechanical equivalent and does not move beyond the last

position. That is, the counter does not wrap around when

clocked to either extreme.

The electronic switches on the device operate in a “make

before break” mode when the wiper changes tap positions. If

the wiper is moved several positions, multiple taps are

a significant amount if the wiper is moved several positions.

When the device is powered-down, the last wiper position

stored will be maintained in the nonvolatile memory. When

power is restored, the contents of the memory are recalled

and the wiper is set to the value last stored.

CS

INC

U/D

MI

(3)

10%

90%

90%