Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier

The MAX9879 combines a high-efficiency stereo Class D audio power amplifier with a stereo capacitor-less DirectDrive® headphone amplifier. Maxim's filterless class D amplifiers with active emissions limiting technology provide Class AB performance with Class D efficiency.

The Class D power amplifier delivers up to 715mW from a 3.7V supply into an 8Ω load with 88% efficiency to extend battery life. The filterless modulation scheme combined with active emission limiting circuitry and spread-spectrum modulation greatly reduces EMI while eliminating the need for output filtering used in traditional Class D devices.

The headphone amplifier delivers up to 58mW from a 3.7V supply into a 16Ω load. Maxim's DirectDrive architecture produces a ground-referenced output from a single supply, eliminating the need for large DC-blocking capacitors, saving cost, space, and component height.

The device utilizes a user-defined input architecture, three preamplifier gain settings, an input mixer, volume control, comprehensive click-and-pop suppression, and I²C control. A bypass mode feature disables the integrated Class D amplifier and utilizes an internal DPST switch to allow an external amplifier to drive the speaker that is connected at the outputs of the MAX9879.

The MAX9879 is available in a thermally efficient, space-saving 30-bump UCSP™ package.

Applications

* Cell Phones * Portable Multimedia Players

* Better than 9dB Margin Under EN 55022 Class B Limits with No Filter Components

* Low RF Susceptibility Design Rejects TDMA Noise from GSM Radios

* Input Mixer with User Defined Input Mode

* Stereo 715mW Speaker Output (RL = 8Ω, VDD = 3.7V)

* Stereo 58mW Headphone Output (16Ω, VDD = 3.7V)

* Low 0.04% THD+N at 1kHz (Class D Power Amplifier)

* Low 0.018% THD+N at 1kHz (Headphone Amplifier)

* 88% Efficiency (RL = 8Ω, POUT = 750mW)

* 1.6Ω Analog Switch for Speaker Amplifier Bypass

* High Speaker Amplifier PSRR (72dB at 217Hz)

* High Headphone Amplifier PSRR (84dB at 217Hz)

* I²C Control

* Hardware and Software Shutdown Mode

* Ultra-Low Click and Pop

* Robust Design with Current and Thermal Protection

* Available in Space-Saving Package

* 5x6 UCSP (2.5mm x 3mm)