MAX9712

500mW, Low EMI, Filterless, Class D Audio Amplifier

500mW, Low-EMI, Filterless, Class D Audio Amplifier Ideal for Portable Applications

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Overview

Filterless Amplifier Passes FCC Radiated Emissions Standards with 100mm of Cable
Unique Spread-Spectrum Mode Offers 5dB Emissions Improvement Over Conventional Methods
Optional External SYNC Input
Simple Master-Slave Setup for Stereo Operation
85% Efficiency
Up to 500mW into 8Ω
Low 0.01% THD+N
High PSRR (72dB at 217Hz)
Integrated Click-and-Pop Suppression
Low Quiescent Current (4mA)
Low-Power Shutdown Mode (0.1µA)
Short-Circuit and Thermal-Overload Protection
Available in Thermally Efficient, Space-Saving Packages
- 10-Pin TDFN (3mm x 3mm x 0.8mm)
- 10-Pin µMAX
- 12-Bump UCSP (1.5mm x 2mm x 0.6mm)

The MAX9712 mono class D audio power amplifier provides class AB amplifier performance with class D efficiency, conserving board space, and extending battery life. Using a class D architecture, the MAX9712 delivers up to 500mW into an 8Ω load while offering efficiencies above 85%. A low EMI modulation scheme renders the traditional class D output filter unnecessary.

The MAX9712 offers two modulation schemes: a fixed-frequency (FFM) mode, and a spread-spectrum (SSM) mode that reduces EMI-radiated emissions due to the modulation frequency. Furthermore, the MAX9712 oscillator can be synchronized to an external clock through the SYNC input, allowing the switching frequency to be user defined. The SYNC input also allows multiple MAX9712s to be cascaded and frequency locked, minimizing interference due to clock intermodulation. The device utilizes a fully differential architecture, a fullbridged output, and comprehensive click-and-pop suppression. The gain is internally set to +4V/V, further reducing external component count.

The MAX9712 features high 72dB PSRR, a low 0.01% THD+N, and SNR in excess of 90dB. Short-circuit and thermal-overload protection prevent the device from damage during a fault condition. The MAX9712 is available in 10-pin TDFN (3mm x 3mm x 0.8mm), 10-pin µMAX®, and 12-bump UCSP™ (1.5mm x 2mm x 0.6mm) packages. The MAX9712 is specified over the extended -40°C to +85°C temperature range.

Applications

Cell Phones
MP3 Players
PDAs
Portable Audio

Documentation

Data Sheet 1

MAX9712: 500mW, Low EMI, Filterless, Class D Audio Amplifier Data Sheet (Rev.1) 02/24/2004

Design Note 1

Thermal Considerations for a UCSP Package 10/15/2007

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Evaluation Kits

Evaluation Kit for the MAX9700A, MAX9700B, MAX9700C, MAX9700D, and MAX9712

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Features and Benefits

Filterless Operation Passes FCC Radiated Emissions
Evaluates the MAX9700A/B/C/D or MAX9712 (with IC Replacement)
2.5V to 5.5V Single-Supply Operation
Up to 94% Efficiency
Drives 1.2W into 8Ω Speaker at 1% THD+N
Differential or Single-Ended Inputs
Selectable Switching Frequency
0.1µA Shutdown Current
Small 10-Pin TDFN Package
Also Available in 10-Pin µMAX® and 12-Bump UCSP™ Packages
Fully Assembled and Tested

Product Details

The MAX9700B evaluation kit (EV kit) is a fully assembled and tested circuit board that uses the MAX9700B filterless class D amplifier to drive a mono bridge-tied-load (BTL) speaker in portable audio applications. Designed to operate from a 2.5V to 5.5V DC power supply, the EV kit is capable of delivering 1.2W into an 8Ω load.

The EV kit accepts differential or single-ended input signals. The EV kit provides an option to select between different switching frequency modes of operation. The MAX9700B EV kit also evaluates the MAX9700A/MAX9700C/MAX9700D and the MAX9712.