DS1866

2 of 5

102199

OPERATION

The DS1866 is a single volatile potentiometer. The device has a total of eight positions providing a

resolution of 5 dB per step and giving a total attenuation range of 0 dB to -35 dB. These tap points are

accessible to the W-terminal whose position is controlled via a 3-terminal parallel port consisting of input

signals P0, P1, and P2. A block diagram of the DS1866 is shown in Figure 1.

Wiper position setting of the DS1866 is determined by the states of the P0, P1, and P2 input terminals.

Table 1 below outlines position setting versus value of the parallel port inputs. A Position-0 setting places

the wiper position at the L-terminal of the potentiometer and provides 35 dB of attenuation. As wiper

position increases, attenuation decreases with Position-7 giving 0 dB of attenuation.

On power-up, the wiper position of the DS1866 will be set to the P0, P1, and P2 values.

P2 P1 P0

(binary)

Wiper

Position

Attenuation

(dB)

000

0

35 dB

001

1

30 dB

010

2

25 dB

011

3

20 dB

100

4

15 dB

101

5

10 dB

110

6

5 dB

111

7

0 dB

PIN DESCRIPTIONS

volts.

GND - Ground Terminal.

H - High-end Resistor. This is the high-end terminal of the potentiometer. It is not required that this

terminal be connected to a potential greater than the L-terminal. Maximum voltage on the H-terminal can

L - Low-end Resistor. This is the low-end terminal of the potentiometer. It is not required that this

terminal be connected to a potential less than the H-terminal. Maximum voltage on the L-terminal can not

W - Wiper of the Potentiometer. This pin is the wiper terminal of the potentiometer. Its position on the

resistor array is controlled by the 3-terminal parallel port. Maximum voltage on the W-terminal can not

P0 - Bit 0. P0 is the bit 0 data input to the parallel port.

P1 - Bit 1. P1 is the bit 1 data input to the parallel port.

P2 - Bit 2. P2 is the bit 2 data input to the parallel port.