DS1802 Datasheet, PDF (6/17 Pages) Dallas Semiconductor – Dual Audio Taper Potentiometer With Pushbutton Control

DS1802
Pulse inputs lasting longer than 1 second will cause the wiper to move one position every 100 ms
following the initial 1 second hold time. The total time to transcend the entire potentiometer using a
continuous input pulse is given by the formula below:
1 (second) + 63 X 100 ms =7.3 (seconds)
Single Contact Closure
Single contact closure operation allows the user to control wiper movement in either direction from a
single pushbutton input. Figure 2(a), as mentioned, presents a typical single pushbutton configuration.
In independent mode control, the UC0 and UC1 inputs are used to increment and decrement each
respective wiper position for single pushbutton mode of operation. The DC0 and DC1 inputs provide no
functionality in the single pushbutton configuration but must be connected to the positive supply voltage
(V_CC). In stereo mode control, the VU and B0 inputs are used to control volume and balance. The VD and
B1 inputs provide no functionality in the single pushbutton configuration but must be connected to the
positive supply voltage (V_CC). The 3-wire serial port inputs ( RST , CLK, and D) must be grounded when
not used.
On device power-up, the configuration shown in Figure 2(a) must exist in order to enter the single contact
closure mode of operation; especially and specifically, the (DC0, DC1, VD, and B1) input’s connection to
the positive supply voltage (V_CC).
The direction of wiper movement in single pushbutton operation is determined by prior activity; with the
direction of wiper movement being opposite to that of the previous activity.
Changing the direction of wiper movement in single pushbutton configuration is accomplish by a period
of inactivity on the controlling input of a (minimum) 1 second or greater. For example, when operating
from independent mode control, an inactivity of 1 second or greater on the UC0 input will cause the
direction of the potentiometer-0 wiper to reverse. The same is true for the UC1 input. Also, in
independent mode control and single pushbutton configuration, as the wiper reaches the end of the
potentiometer range its direction of movement reverses. This will occur regardless of whether the input is
a continuous pulse, a sequence of repetitive pulses or a single pulse.
In stereo mode control, the VU input is responsible for both directions of wiper movement. Again, a
period of inactivity will allow the direction of volume to be reversed. Additionally, if either wiper
reaches a peak position, the direction of movement will automatically reverse.
For balance mode control, the B0 input will be responsible for wiper movement. A period of inactivity
lasting 1 second or more will cause a switch in balance movement (i.e., balance-0 to balance-1).
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