DS1804

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OPERATION

The DS1804 is a single nonvolatile potentiometer. The device has a total of 100 tap-points including the

L- and H- terminals. A total of 99 resistive segments exist between the L- and H- terminals. These tap-

points are accessible to the W-terminal, whose position is controlled via a three-terminal control port. A

block diagram of the DS1804 is shown in Figure 1.

The three-terminal port of the DS1804 provides an increment/decrement interface which is activated via a

control a 7-bit up/down counter. The output of the 7-bit up/down counter controls a 1 of 100 decoder to

INC

input control pins. The timing diagram for the three-terminal interface control is shown in Figure 2.

PIN DESCRIPTIONS

GND - Ground.

H - High-Terminal Potentiometer. This is the high terminal of the potentiometer. It is not required that

this terminal be connected to a potential greater than the L-terminal. Voltage applied to the H-terminal

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

terminal be connected to a potential less than the H-terminal. Voltage applied to the L-terminal cannot

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

array is controlled by the three-terminal control port. Voltage applied to the wiper cannot exceed the

CS

position.

INC

Wiper position changes of the W-terminal will occur one position per high-to-low transition of this input

position of the wiper to move towards the L-terminal.