Stereo Audio Taper Potentiometers

with Pushbutton Interface

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7

Detailed Description

The MAX5456/MAX5457 dual, logarithmic taper digital

potentiometers feature a simple pushbutton interface that

controls volume and balance in audio applications. Each

potentiometer has 32 tap points and replaces mechanical

potentiometers (see the Functional Diagrams).

Up and Down Interface

The MAX5456/MAX5457 interface with momentary con-

tact SPST switches. All switch inputs are internally

Ω

resistors. The wiper setting advances once per button

press up to 1s. Maxim’s SmartWiper control circuitry

allows the wiper to advance at a rate of 4Hz when an

input is held low from 1s up to 4s, and at a rate of 16Hz

if the contact is maintained for greater than 4s (see

Table 2). The SmartWiper control eliminates the need for

a microcomputer to increase the wiper transition rate.

The MAX5456 features independent control inputs for

volume and balance control while the MAX5457 MODE

input toggles between volume and balance control.

Each transition of MODE from high to low toggles the

MAX5457 between volume-control and balance-control

modes. MODE is internally pulled high with a 50k

Ω

Volume Control

In volume-control mode, the MAX5456/MAX5457s’

wipers move simultaneously, maintaining the balance

separation between each wiper (Figure 3a).

When either wiper reaches the maximum tap position

(position closest to H_), further commands to increase

the volume are ignored. Balance separation is main-

tained in the maximum volume configuration (Figure 3b).

When either wiper reaches the minimum tap position

(position closest to L_), further commands to decrease

the volume adjust the other wiper until it also reaches

the minimum tap position (Figure 3c).

Increasing the volume from this minimum position

restores the original balance separation of the wipers

(Figure 3d).

When both wipers are in the 31st tap position (-62dB

attenuation), further commands to VOLDN place the

wipers in the mute position (see Table 1). VOLUP or

MUTE pulses return wipers to position 31.

MAX5456

MAX5457

W_

H_

L_

R

Figure 1. Potentiometer Model (Active)

MAX5456

MAX5457

W_

H_

L_

R

Figure 2. Potentiometer Model (Shutdown)