Maxim MAX98400 MP3坞站D类放大器参考设计

电子工程师 2019-03-20 1072

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关键词： D类放大器 , MAX98400 , Maxim , MP3 , 坞站

Maxim公司的MAX98400A/MAX98400B是高性能热效率高的D类音频放大器, MAX98400A能向8欧姆负载提供2x20W或向4欧姆负载提供1x40W, MAX98400B则向8欧姆负载提供2x8W功率.单电源8V 到28V工作,提供67dB PSRR,12V时的效率高达90%,主要用在LCD/PDP TV,LCD监视器,MP3坞站和笔记本PC.本文介绍了MAX98400A/MAX98400B主要特性, MAX98400A/B功能方框图,以及MAX98400A立体声和单声道配置图, MAX98400 D类音频放大器参考设计主要特性,电路图,材料清单和PCB布局图.

The MAX98400A/MAX98400B Class D amplifiers provide high-performance, thermally efficient amplifier solutions. The MAX98400A delivers 2x20W into 8I loads or 1x40W into a 4I load. The MAX98400B delivers 2x12W into 8I loads.

An integrated limiting circuit prevents output clipping distortion, protects small speakers from transient voltages, and reduces power dissipation.

A thermal-foldback feature can be enabled to automatically reduce the output power at above a junction temperature of +120NC. Traditional thermal protection is also available in addition to robust overcurrent protection.

The ICs operate from a single 8V to 28V supply and provide a high 67dB PSRR, eliminating the need for a regulated power supply. They offer up to 90% efficiency from a 12V supply.

Filterless modulation allows the ICs to pass EN55022B EMI limits with 1m cables using only a low-cost ferrite bead and small-value capacitor on each output. Both devices feature eight digitally controlled gain settings.

Comprehensive click-and-pop reduction circuitry minimizes noise coming into and out of shutdown.

The MAX98400A/MAX98400B are available in 36-pin and 24-pin TQFN packages, respectively, and are specified over the -40NC to +85NC temperature range.

MAX98400A/MAX98400B主要特性:

Wide 8V to 28V Supply Voltage Range

Single-Supply Operation

Low EMI: Active Emissions Limiting

Clipping Limiter

Low Quiescent Current

Thermal Foldback

Thermal and Overcurrent Protection

MAX98400A/MAX98400B应用:

LCD/PDP Televisions

LCD Monitors

MP3 Docking Stations

Notebook PCs

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图1.MAX98400A功能方框图

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图2.MAX98400B功能方框图

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图3.MAX98400A立体声配置图

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图4.MAX98400A单声道配置图

MAX98400 D类音频放大器参考设计

This reference design demonstrates the use of the MAX98400 Class D audio amplifier in a stereo audio docking station application. The MAX98400 2.1 demo box is a complete powered speaker dock that uses two MAX98400 ICs to drive a 3-channel speaker system consisting of two 2in satellite speakers and one 5in subwoofer. The reference design is intended to be used with a portable audio player as its main music source. The overall solution size is very compact and features active equalization, powersupply monitoring, and dynamic equalization for the subwoofer.

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图5. MAX98400 D类音频放大器参考设计外形图

MAX98400 D类音频放大器主要设计特性:

Compact all-in-one design

Operates from a single 12V to 20V DC power supply

High SPL output from a small box

High-efficiency Class-D design

Active EQ, including dynamic bass equalization

Excellent sound quality from cost-effective drivers