10

FN6912.1

April 15, 2010

Pin Description

Potentiometers Pins

RH AND RL

The high (RH) and low (RL) terminals of the ISL22317 are

equivalent to the fixed terminals of a mechanical

potentiometer. RH and RL are referenced to the relative

position of the wiper and the voltage potential on the

terminals. With WR set to 127 decimal, the wiper will be

closest to RH. With the WR set to 0, the wiper is closest to

RL. The voltage potential on the RH terminal must be higher

than voltage potential on RL terminal.

RW

RW is the wiper terminal and is equivalent to the movable

terminal of a mechanical potentiometer. The position of the

wiper within the array is determined by the WR register.

REF_A, REF_B

REF_A and REF_B are pins to connect an external resistor.

If application is required to connect RL terminal to GND, then

the REF_B pin should also be connected to GND.

Warning! Do not connect REF_A to GND under any

circumstances. That may damage the ISL22317.

Bus Interface Pins

SERIAL DATA INPUT/OUTPUT (SDA)

interface. It receives device address, operation code, wiper

rising edge of the serial clock SCL, and it shifts out data after

each falling edge of the serial clock.

SDA requires an external pull-up resistor, since it is an open

drain input/output.

SERIAL CLOCK (SCL)

DEVICE ADDRESS (A1)

interface slave address, see Table 4. A match in the slave

address serial data stream must match with the Address

input pins in order to initiate communication with the

FIGURE 17. TC FOR RHEOSTAT MODE (10k/50k/100k) IN ppm

FIGURE 18. TC FOR VOLTAGE DIVIDER MODE (10k/50k/100k)

FIGURE 20. WIPER RESISTANCE vs TAP POSITION WHEN

PRECISION IS OFF

0

10

20

30

40

15

35

55

75

95

115

TAP POSITION (DECIMAL)

0

10

20

30

40

15

35

55

75

95

115

TAP POSITION (DECIMAL)

0

200

400

600

800

-40

0

40

80

120

TEMPERATURE (°C)

0

20

40

60

80

100

0

20406080

100

120

TAP POSITION (DECIMAL)

T = +125°C

T = +25°C

T = -40°C

ISL22317