Maxim公司的MAX98380是集成容性升压转换器的小型单声道数字输入D类音频放大器.器件具有基于三倍电荷泵升压转换器,能向8Ω负载提供高达1% THD+N的4.85W功率.容性升压替代所需的大和贵的电感,以降低总PCB解决方案.此外由于电池寿命降低而引起电源电压变化,片上限制器(DHT)自动优化D类放大器的可用净空高度,以维持一致性失真和听觉水平.当器件的热限制达到时热折返保护保证了鲁棒性能,而当温度超过用户指定的阈值时器件能自动降低输出功率.这就使得在高环境温度时不间断的音乐播放.除了稳健的过电流保护,传统的热保护也可提供.器件提供用于音频数据的PCM接口和用于控制数据通信的I2C接口.PCM接口支持采用I2S,左对准和TDM音频数据格式的音频播放.独特的时钟结构消除了用于PCM通信的外接主时钟.除了降低尺寸和引脚数量,还降低EMI和可能的板耦合问题. VBAT = 3.7V时6Ω负载的输出功率为3.6W,总静态功耗为10mW,80%效率(RL = 8Ω时1.0W, VBAT = 3.7V).工作温度-40°C 到+85°C.主要用在智能手机,智能扬声器,IoT设备和平板电脑.本文介绍了MAX98380主要优势和特性,简单框图和详细框图, 典型应用电路图和评估系统MAX98380 EVS主要特性,电路图,材料清单和PCB设计图.

The MAX98380 is a small, mono Class-D audio amplifier featuring an integrated capacitive boost converter. The device implements a tripler charge pump-based boost converter that efficiently delivers up to 4.85W at 1% THD+N into an 8Ω load. The capacitive boost replaces the large and expensive inductor required for an inductive boost with smaller, lower-profile capacitors that reduce the total PCB solution.

Additionally, as the power-supply voltage varies due to declining battery life, an on-chip limiter (DHT) automatically optimizes the headroom available to the Class-D amplifier to maintain consistent distortion and listening levels.

Thermal-foldback protection ensures robust behavior when the thermal limits of the device are reached. When enabled, it automatically reduces the output power when the temperature exceeds a user-specified threshold. This allows for uninterrupted music playback even at high ambient temperatures. Traditional thermal protection is also available in addition to robust overcurrent protection.

The device provides a PCM interface for audio data and a standard I2C interface for control data communication. The PCM interface supports audio playback using I2S, left-justified, and TDM audio data formats. A unique clocking structure eliminates the need for an external master clock for PCM communication. This reduces EMI and possible board coupling issues in addition to reducing the size and pin count.

Active emissions-limiting and edge-rate limiting circuitry greatly reduce EMI. A filterless spread-spectrum modulation scheme eliminates the need for output filtering found in traditional Class-D devices and reduces the component count of the solution.

The IC is available in a 0.35mm pitch 24-bump wafer-level package (WLP). It is specified over the extended, -40°C to +85°C temperature range.

MAX98380主要优势和特性:

● Integrated Capacitive Boost Converter—No Bulky Inductors

● 3.6W Output Power into 6Ω at VBAT = 3.7V

● 10mW Total Quiescent Power

● 3ms Turn-On Time

● 80% Efficiency (1.0W into RL = 8Ω, VBAT = 3.7V)

● 19.8μVRMS Speaker Mode Output Noise

● 16.5μVRMS Receiver Mode Output Noise

● Low 0.005% THD+N at 1kHz

● No MCLK Required

● Sample Rates of 8kHz to 192kHz

● Supports Left, Right, or (Left/2 + Right/2) Output in I2S and Left-Justified Modes

● Sophisticated Edge Rate Control Enables Filterless Class-D Outputs

● Low RF Susceptibility Rejects TDMA Noise from GSM Radios

● Class-D Switching Frequency Trimmed to 10% for Better EMI Planning

● Extensive Click-and-Pop Reduction Circuitry

● Dynamic Headroom Tracking (DHT)

● Robust Short-Circuit and Thermal Protection

● Available in Space-Saving Package: 1.468mm x 2.138mm, 24-Bump WLP (0.35mm Pitch)

MAX98380应用:

● Smartphones

● Smart Speakers

● IoT Devices

● Tablets

图1. MAX98380简化框图

图2. MAX98380详细框图

图3. MAX98380典型应用电路图

评估系统MAX98380 EVS

 The MAX98380 evaluation system (EV system) is a fully assembled and tested system that evaluates the MAX98380 boosted Class-D audio amplifier. The EV system consists of the MAX98380 Development Board (DEV board), Analog Devices Audio Interface Board III (AUDINT3), and a USB cable.

It is recommended that the DEV board be evaluated with the AUDINT3 board, as an EV system. The MAX98380 supports standard I2S, left-justified, and TDM digital audio interfaces.

The AUDINT3 board provides a USB-to-PCM interface in addition to a 1.8V VDD supply needed to evaluate the DEV board. The MAX98380 DEV board requires one additional supply input, 2.5V to 5.5V (VBAT) when evalu­ating using the AUDINT3 board. Figure 1 details the DEV board and the AUDINT3 board.

评估系统MAX98380 EVS主要特性:

2.5V to 5V Single-Supply Operation

USB Audio Streaming (EV System)

I2S, Left-Justified, or TDM Input

Capacitive Charge Pump Boost Circuitry

Fully Assembled and Tested

评估系统MAX98380 EVS包括:

MAX98380 Development Board

Audio Interface Board III

Micro-USB Cable

图4. 评估系统MAX98380 EVS外形图

图5. 评估系统MAX98380 EVS电路图

评估系统MAX98380 EVS材料清单:

图6. 评估系统MAX98380 EVS PCB设计图:左:顶层丝印;右:层2

图7. 评估系统MAX98380 EVS PCB设计图:左:顶层布局;右:层3

图8. 评估系统MAX98380 EVS PCB设计图:左:层4;右:底层

图9. 评估系统MAX98380 EVS PCB设计图:左:层5;右:底层丝印