Maxim 公司的MAX98304是單聲道3.2W D類(lèi)音頻放大器，提供AB類(lèi)音頻性能和D類(lèi)效率，提供五種引腳選擇的增益（0dB,3dB,6dB,9dB和12dB），3.7V的靜態(tài)電流0.95mA，超低噪音19μVRMS，PSRR為90dB，開(kāi)關(guān)噪音抑制，熱和過(guò)流保護，低電流關(guān)斷模式。主要應用在筆記本和上網(wǎng)本電腦，手機，平板電腦，MP3播放器，手持音頻播放器，VoIP電話(huà)。本文介紹了MAX98304主要特性，功能方框圖，典型應用電路圖，MAX98304評估板主要特性，電路圖，材料清單和PCB元件布局圖。
The MAX98304 mono 3.2W Class D amplifier provides Class AB audio performance with Class D efficiency. This device offers five selectable gain settings (0dB, 3dB, 6dB, 9dB, and 12dB) set by a single gain-select input (GAIN).
Active emissions-limiting, edge-rate, and overshoot control circuitry greatly reduces EMI. A filterless spreadspectrum modulation scheme eliminates the need for output filtering found in traditional Class D devices. These features reduce application component count.
The IC’s 0.95mA at 3.7V (1.2mA at 5V) quiescent current extends battery life in portable applications.
The IC is available in a 9-bump (1.0mm x 1.0mm) WLP with 0.3mm pitch that is specified over the extended -40NC to +85NC temperature range.

MAX98304主要特性：
Low Quiescent Current: 0.95mA at 3.7V
Spread Spectrum and Active Emissions Limiting
Five Pin-Selectable Gains
19μVRMS Ultra-Low Noise
90dB PSRR
Click-and-Pop Suppression
Thermal and Overcurrent Protection
Low-Current Shutdown Mode
1.0mm x 1.0mm, 9-Bump WLP (0.3mm Pitch) Space-Saving Package

MAX98304應用：
Notebook and Netbook Computers
Cellular Phones
Tablets
MP3 Players
Portable Audio Players
VoIP Phones

圖1。MAX98304功能方框圖

圖2。MAX98304典型應用電路圖

MAX98304評估板
The MAX98304 evaluation kit (EV kit) is a fully assembled and tested circuit board that uses the MAX98304 filterless Class D amplifier to drive a speaker in portable audio applications. The EV kit comes with a MAX98304EWL+ in a 9-bump, 0.3mm pitch wafer-level package (WLP). Designed to operate from a 2.5V to 5.5V DC power supply, the EV kit is capable of delivering 3.2W into a 4Ω load. The EV kit accepts differential or single-ended input signals.

MAX98304評估板主要特性:
Filterless Operation Passes Radiated Emissions with 60cm of Speaker Cable
2.5V to 5.5V Single-Supply Operation
3.2W Mono Class D Output
Selectable Gain Control
Differential or Single-Ended Input
Low-Power Shutdown Input
Fully Assembled and Tested

圖3。MAX98304評估板電路圖
MAX98304評估板材料清單（BOM）：


圖4。MAX98304評估板元件布局圖