DS1866
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)
000
001
010
011
100
101
110
111
Wiper
Position
0
1
2
3
4
5
6
7
Attenuation
(dB)
35 dB
30 dB
25 dB
20 dB
15 dB
10 dB
5 dB
0 dB
PIN DESCRIPTIONS
V
CC
- Power Supply Terminal.
The DS1866 will support supply voltages ranging from +2.7 to +5.5
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
not exceed the power supply voltage, V
CC
, or go below ground.
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
exceed the power-supply voltage, V
CC
, or go below ground.
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
exceed the power supply voltage, V
CC
, or go below ground.
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.
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DALLAS [ DALLAS SEMICONDUCTOR ]
