Low RF Susceptibility Mono Audio Subsystem with DirectDrive Headphone Amplifier

The MAX9877 combines a high-efficiency Class D audio power amplifier with a stereo Class AB capacitor-less DirectDrive® headphone amplifier. Maxim's 3rd generation, filterless Class D amplifier with active emissions limiting technology provides Class AB performance with Class D efficiency.

The MAX9877 delivers up to 725mW from a 3.7V supply into an 8Ω load with 87% efficiency to extend battery life. The filterless modulation scheme combined with active emissions limiting circuitry and spread-spectrum modulation greatly reduces EMI while eliminating the need for output filtering used in traditional Class D devices.

The stereo Class AB headphone amplifier in the MAX9877 uses Maxim's DirectDrive architecture, that 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 MAX9877.

The MAX9877 is available in a thermally efficient, space-saving 20-bump WLP package.

Applications

* Cell Phones * Portable Multimedia Players

* Low Emissions, Filterless Class D Amplifier Achieves Better than 10dB Margin Under EN55022 Class B Limits

* Low RF Susceptibility Design Rejects TDMA Noise from GSM Radios

* Input Mixer with User-Defined Input Mode

* 725mW Speaker Output (RSPK = 8Ω, PVDD = 3.7V)

* 53mW Headphone Output (RHP = 16Ω, VDD = 3.7V)

* Low 0.05% THD+N at 1kHz (Class D Power Amplifier)

* Low 0.016% THD+N at 1kHz (Headphone Amplifier)

* 87% Efficiency (RSPK = 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

* Click-and-Pop Suppression

* Current-Limit and Thermal Protection

* Available in a Space-Saving, 2.5mm x 2.0mm WLP Package