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FN8241.3

September 5, 2006

Principles of Operation

The ISL95711 is an integrated circuit incorporating one DCP

with it’s associated register, non-volatile memory, and the

a host and the potentiometer and memory. The resistor array

is comprised of 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.

When the device is powered-down, the last value stored in

the IVR will be maintained in the nonvolatile memory. When

power is restored, the contents of the IVR are recalled and

the wiper is set to that value.

operation of the chip, it is recommended both power

supplies ramp up simultaneously to their final values within

20ms. The chip design gives priority to the V- supply

value (this is referred as power on recall).

DCP Description

The DCP is implemented with a combination of resistor

elements and CMOS switches. The physical ends of the

DCP are equivalent to the fixed terminals of a mechanical

intermediate nodes, and is equivalent to the wiper terminal

of a mechanical potentiometer. The position of the wiper

terminal is controlled by a 7-bit volatile Wiper Register (WR).

When the WR contains all zeroes (00h), the wiper terminal

from all zeroes (00h) to all ones (7Fh), the wiper moves

While the ISL95711 is being powered up, the WR is reset to

becomes large enough for reliable non-volatile memory

reading (~ ±2.5V), the ISL95711 reads the value stored on a

non-volatile Initial Value Register (IVR) and loads it into the

WR.

The WR and IVR can be read or written directly using the

Memory Description

The ISL95711 contains 1 non-volatile byte know as the Initial

operations with Address 00h. The IVR contains the value

which is loaded into the Volatile Wiper Register (WR) at

power-up.

The volatile WR, and the non-volatile IVR of a DCP are

accessed with the same address.

FIGURE 13. WIPER MOVEMENT

FIGURE 14. LARGE SIGNAL SETTLING TIME

ISL95711