ISL95310

FN8083 Rev 1.00

Page 7 of 9

August 27, 2015

have a monotonic ramp to the specified operating voltage. It

least 2.5V in less than 7.5ms (0.2V/ms). The ramp rate

before and after these thresholds is not important.

not affect the proper recall of the wiper position, applying V+

before the electronic switch control signals are applied. This

can result in multiple electronic switches being turned on,

which could load the power supply and cause brief,

unexpected potentiometer wiper settings.

To prevent unknown wiper positions on the ISL95310 on

power down, it is recommended that V+ turn off before or

off, the wiper position can remain unchanged from its

previous setting or it can go to an undefined state.

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 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 memory

whenever CS transitions HIGH while the INC input is also

HIGH.

The system may select the ISL95310, 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 power-up/down cycle

recalled the previously stored data.

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, 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.

During initial power-up CS must go high along with or before

TABLE 1. 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

H

H

X

Standby

L

H

Wiper up one position

(not recommended)

L

L

Wiper down one position

(not recommended)