DP7112 datasheet(3/10 Pages) COPAL

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DP7112

Pin Description

INC: Increment Control Input

The INC input (on the falling edge) moves the wiper in the

up or down direction determined by the condition of the U/D

input.

U/D: Up/Down Control Input

The U/D input controls the direction of the wiper movement.

When in a high state and CS is low, any high to low

transition on INC will cause the wiper to move one

increment toward the RH terminal. When in a low state and

CS is low, any high to low transition on INC will cause the

wiper to move one increment towards the RL terminal.

RH: High End Potentiometer Terminal

RH is the high end terminal of the potentiometer. It is not

required that this terminal be connected to a potential greater

than the RL terminal. Voltage applied to the RH terminal

cannot exceed the supply voltage, VCC or go below ground,

GND.

RWB: Wiper Potentiometer Terminal (Buffered)

RWB is the buffered wiper terminal of the potentiometer. Its

position on the resistor array is controlled by the control

inputs, INC, U/D and CS.

RL: Low End Potentiometer Terminal

RL is the low end terminal of the potentiometer. It is not

required that this terminal be connected to a potential less

than the RH terminal. Voltage applied to the RL terminal

cannot exceed the supply voltage, VCC or go below ground,

GND. RL and RH are electrically interchangeable.

CS: Chip Select

The chip select input is used to activate the control input of

the DP7112 and is active low. When in a high state, activity

on the INC and U/D inputs will not affect or change the

position of the wiper.

Device Operation

The DP7112 operates like a digital potentiometer

with RH and RL equivalent to the high and low

terminals

and

RWB equivalent to the mechanical

potentiometer s wiper. There are 32 available tap positions

including the resistor end points, RH and RL. There are 31

resistor elements connected in series between the RH and RL

terminals. The wiper terminal is connected to one of the 32

taps and controlled by three inputs, INC,U/D and CS. These

inputs control a five bit up/down counter whose output is

decoded to select the wiper position. The selected wiper

position can be stored in nonvolatile memory using the INC

and CS inputs.

With CS set LOW the DP7112 is selected and will

respond to the U/D and INC inputs. HIGH to LOW

transitions on INC will increment or decrement the wiper

(depending on the state of the U/D input and five bit

counter). The wiper, when at either fixed terminal, acts like

its mechanical equivalent and does not move beyond the last

position. The value of the counter is stored in nonvolatile

memory whenever CS transitions HIGH while the INC input

stored wiper counter position is maintained in the

nonvolatile memory. When power is restored, the contents

of the memory are recalled and the counter is set to the value

stored.

With INC set low, the DP7112 may be deselected and

powered down without storing the current wiper position in

nonvolatile memory. This allows the system to always

power up to a preset value stored in nonvolatile memory.

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