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Audio controller adjusts volume, balance with rotary encoder interface

Posted: 08 May 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Maxim Integrated Products? Maxim? MAX5440? volume? balance?

Maxim Integrated Products Inc. has introduced the MAX5440 controller featuring a debounced encoder IC provides 12-bit resolution at low rotational speeds" target=_blank>rotary encoder interface that directly controls volume and balance without using a microcontroller or GPIO.

This new product has an integrated algorithm that separately controls volume and balance. Buffered wiper outputs allow the device to connect directly to the audio circuit's power amplifier. An integrated bias generator provides the necessary [(VDD+VSS)/2] voltage for unipolar input signals, eliminating the need for costly external bias circuitry and saving board space.

The MAX5440's rotary-encoder interface uses grayscale coding to move the wiper up and down the 40 kilohms resistor string. A mute function sets all wipers to maximum attenuation when activated, and returns the wipers to their previous position when deactivated.

A shutdown feature sets the wipers to maximum attenuation and disconnects H_ from the signal path when activated. Deactivating shutdown returns the wipers to their previous position. In addition, an integrated glitch suppression circuitry ensures "clickless" switching between wiper transitions.

The MAX5440 also provides an open-drain LED mode indicator that specifies volume or balance-control mode. Separate LED inputs indicate volume level or balance shift, depending on the operating mode.

The device provides temperature coefficient of 5ppm/Celsius end-to-end and 35ppm/Celsius ratiometrically. This audio controller saves power by operating from a 2.7V to 5.5V single supply or 2.7V dual supply, and by consuming less than 0.5?A in standby.

Available in a 24-pin SSOP package, the device is touted to be smaller than mechanical potentiometers and associated external circuitry able to perform the same tasks. Prices start at $1.47 (1000-up, FOB USA).

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