DP7110, DP7118, DP7119, DP7123, DP7124, DP7125

5

Functional Description

The DP7110/7118/7119/7123/7124/7125 consist of a

fixed resistor and a wiper contact with 32 tap points that are

digitally controlled through a 2 wire up/down serial

interface. Three end to end resistance values are available:

10 k , 50 k

and 100 k .

The DP7110/7125 is designed to operate as a

potentiometer. In this configuration, the low terminal of the

resistor array is connected to ground (pin 2).

The DP7118/7123 performs as a variable resistor. In this

device, the wiper terminal and high terminal of the resistor

array are connected at pin 5. The DP7119/7124 is a similar

variable resistor, except the low terminal is connected to

pin 5.

Digital Interface Operation

The devices have two modes of operation when the

serial interface is active: increment and decrement mode.

The serial interface is only active when CS is low.

The CS and U/D inputs control the position of the wiper

along the resistor array. When CS transitions from high to

low, the part will go into increment mode if U/D input is

high, and into decrement mode when U/D input is low. Once

the mode is set, the device will remain in that mode until CS

goes high again. A low to high transition at the U/D pin

will increment or decrement the wiper position depending

on the current mode (Figures 7 and 8).

When the CS input transitions to high (serial interface

inactive), the value of the counter is stored and the wiper

position is maintained.

Note that when the wiper reaches the maximum (or

minimum) tap position, the wiper will not wrap around to the

minimum (or maximum) position.

Power On Reset

All parts in this family feature power on reset (POR)

circuitry that sets the wiper position to midscale at

power up. By default, the chip is in the increment mode.

Figure 7. Serial Interface Timing Diagram, Increment Mode

W

U/D

CS

Note: “W” is not a digital signal. It represents wiper transitions.

Figure 8. Serial Interface Timing Diagram, Decrement Mode

W

Note: “W” is not a digital signal. It represents wiper transitions.

U/D

CS