DS1666, DS1666S

022698 2/7

GRAPH OF AUDIO TAPER Figure 1

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5

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LOW TERMINAL

HIGH TERMINAL

% OF ACTIVE DIGITAL TAPS

1

3

2

1

OPERATION

The CS, U/D and INC inputs control the position of the

wiper along the resistor array (Figure 1). When CS is ac-

tive (low), a high to low transition on the INC will incre-

ment or decrement an internal counter depending on the

level of the U/D pin. When the U/D pin is low, the counter

will decrement. When the U/D pin is high, the counter will

increment. The state of the U/D pin can be changed while

CS is active allowing for precise adjustment during cali-

bration. The output of the counter is decoded to set the

position of the wiper. When the CS input transitions to the

high (inactive) level, the value of the counter is stored and

When power is restored, the DS1666 returns to the de-

fault setting and positions the wiper to 10 percent. The

value of the end–to–end and end–to–wiper position is in-

The DS1666 has a resistor array that resembles an au-

dio taper potentiometer as shown in Figure 1 1. Since

the taper is not linear, exact resistance values for each

of the 128 positions of the resistor is not specified. How-

ever, the end-to-end resistance is specified to be within

±20 percent of the stated resistor value over an indus-

trial temperature range of –40

°C to +85°C.

ANALOG CHARACTERISTICS

End–to–End Resistance Tolerance =

±20 percent

Typical Noise = <120 dB/Hz REF:IV

Temperature Coefficient =

±800 PPM/°C typical

Resistance at tap #74=18%

± 2% of total resistance.

PIN DESCRIPTIONS

The high end of the potentiometer. This

terminal is capable of handling input volt-

ages between

±5 volts.

The Low end of the potentiometer. This

terminal is capable of handling input volt-

ages between

±5 volts.

The wiper terminal of the potentiometer.

The value of the wiper is controlled by the

U/D and the INC pins.

Up/Down

The

U/D

input

controls

the

direc-

(U/D)

tion of the wiper movement when setting

the potentiometer.

Increment

Toggling INC will move the potentiome-

(INC)

ter wiper by either incrementing or decre-

menting the counter.

Chip Select The device is selected when CS input is

(CS)

low. The current counter value is stored

when CS is returned high.