3-Channel, 2.3W, Filterless Class D Amplifiers with Active Crossover

The MAX9706/MAX9707 combine three high-efficiency Class D amplifiers with an active crossover to provide stereo highpass outputs, and a mono lowpass output. All three channels deliver up to 2.3W at 1% THD+N per channel into 4Ω when operating from a 5V supply.

An internal active filter processes the stereo inputs (left and right) into stereo highpass and mono lowpass outputs. The crossover frequency is pin-selectable to four different frequencies to accommodate a variety of speaker configurations. The internal Class D amplifiers feature low-EMI, spread-spectrum outputs. No output filters are required.

The MAX9706 features Maxim's DirectDrive® headphone amplifier, providing ground-referenced headphone outputs without the need for bulky DC-coupling capacitors. The headphone outputs are capable of delivering 95mW per channel into 16Ω from a 3.3V supply, and are protected against ESD up to ±8kV.

The MAX9706/MAX9707 feature pin-programmable gain, synchronization inputs and outputs, and a shutdown mode that reduces supply current to less than 1µA. All amplifiers feature click-and-pop suppression circuitry. Both devices are fully specified over the -40°C to +85°C extended temperature range and are available in the thermally enhanced 36-pin (6mm x 6mm x 0.8mm) thin QFN package.

Applications

* 2.1 Speaker Solutions * Desktop PCs * Multimedia Monitors * Notebook Audio Solutions * Portable DVD Players * Table-Top LCD TVs

* Triple Class D Amplifiers Deliver 3 x 2.3W into 4Ω

* Internal Active Crossover Filter with Adjustable Crossover Frequency

* Low-EMI, Spread-Spectrum Modulation

* Low 0.02% THD+N

* High PSRR (71dB)

* DirectDrive Headphone Amplifier (MAX9706)

* Enhanced Click-and-Pop Suppression

* Input and Output Modulator Synchronization

* Low-Power Shutdown Mode

* Up To 90% Efficiency

* Space-Saving (6mm x 6mm x 0.8mm) 36-Pin Thin QFN Package