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Audio controller features pushbutton interface

Posted: 21 Nov 2006 ?? ?Print Version ?Bookmark and Share

Keywords:Maxim? MAX5486? audio controller? pushbutton interface? SmartWiper?

Maxim Integrated Products has introduced a dual, 32-tap audio controller with a debounced pushbutton interface for volume and balance control. The MAX5486 audio controller does not require an external MCU, GPIO or any debounce circuitry for the control interface.

An integrated algorithm separately controls volume and balance. The integrated buffered wiper outputs allow the new device to connect directly to the power amplifier of the audio circuit and an integrated bias generator provides the necessary voltage [(Vdd - Vss)/2] for unipolar input signals. This design eliminates the need for costly external bias circuitry, the company said, ultimately saving design time, costs and board space.

The controller's three-wire pushbutton interface features the company's proprietary enhanced SmartWiper rapid-advance wiper-control system. SmartWiper control advances the wiper at a rate of 4Hz when the switch is closed between 250ms and 500ms, 8Hz when the switch is closed between 500ms and 1s, and 11Hz when the switch is closed for more than 1s. A mute function can be activated to set all wipers to maximum attenuation; when deactivated, it returns the wipers to their previous position. A shutdown feature can set the wipers to maximum attenuation and disconnect a potentiometer high terminal from the signal path. Deactivating shutdown returns the wipers to their previous position.

Each channel includes integrated suppression circuitry that ensures "click-less" switching between wiper transitions, power-up, power-down and mode transitions.

The MAX5486 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.

Two 40-kiloohm resistor strings offer ratiometric and end-to-end temperature coefficients as low as 5ppm/C and 35ppm/C, respectively. This controller saves power by operating from a 2.7-5.25V single supply or a dual 2.7V supply. Moreover, it requires less than 0.5?A in standby. Available in a 6-by-5mm, 24-pin TSSOP package, the MAX5486 offers significant size reduction compared to mechanical potentiometers. Prices start at $1.57 (1,000-up, FOB USA).

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