Windows Vista-Compliant Class D Speaker Amplifiers with DirectDrive Headphone Amplifiers

Active: In Production.

The MAX9791 combines a stereo 2W Class D power amplifier, a stereo 180mW DirectDrive® headphone amplifier, and a 120mA low-dropout (LDO) linear regulator in a single device. The MAX9792 combines a mono 3W Class D power amplifier, a stereo 180mW DirectDrive headphone amplifier, and a 120mA LDO linear regulator in a single device.

The MAX9791/MAX9792 feature Maxim's DirectDrive headphone amplifier architecture that produces a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, saving cost, board space, and component height. High 107dB DC PSRR and low 0.006% THD+N ensure clean, low-distortion amplification of the audio signal.

The ground sense feature senses and corrects for the voltage difference between the output jack ground and device signal ground. This feature minimizes headphone amplifier crosstalk by sensing the impedance in the ground return trace and correcting for it at the output jack. This feature also minimizes ground-loop noise when the output socket is used as a line out connection to other grounded equipment (for example, a PC connected to a home hi-fi system).

The MAX9791/MAX9792 feature low RF susceptibility, allowing the amplifiers to successfully operate in close proximity to wireless applications. The MAX9791/MAX9792 Class D amplifiers feature Maxim's spread-spectrum modulation and active emissions limiting circuitry. Industry-leading click-and-pop suppression eliminates audible transients during power-up and shutdown cycles.

The MAX9791/MAX9792 wake-on-beep feature wakes up the speaker and headphone amplifiers when a qualified beep signal is detected at the BEEP input.

For maximum flexibility, separate speaker and headphone amplifier control inputs provide independent shutdown of the speaker and headphone amplifiers. Additionally the LDO can be enabled independently of the audio amplifiers.

The MAX9791/MAX9792 feature thermal-overload and output short-circuit protection. The devices are available in 28-pin TQFN packages and are specified over the -40°C to +85°C extended temperature range.

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