Stereo Class D Audio Subsystem with DirectDrive Headphone Amplifier

 

Part Number	Replacement	Explanation

Description

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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.

MAX9879: Simplified Block Diagram Enlarge+

Key Features

• 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 (R_L = 8Ω, V_DD = 3.7V)
• Stereo 58mW Headphone Output (16Ω, V_DD = 3.7V)
• Low 0.04% THD+N at 1kHz (Class D Power Amplifier)
• Low 0.018% THD+N at 1kHz (Headphone Amplifier)
• 88% Efficiency (R_L = 8Ω, P_OUT = 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)

Applications/Uses

• Cell Phones
• Portable Multimedia Players