UM10155Discrete Class D High Power Audio AmplifierUM10155：分立元件D类大功率音频功放Keywords ：Class D Audio Amplifier, Universal Class D, UcD, PWM Audio Amplifier,High Power Audio.关键词：D类音频放大器，全D类（UcD）, PWM功放，大功率功放Abstract ：This user manual describes the operating instructions and the most important background information of the Philips Semiconductor Discrete Class D High Power Audio Amplifier Demonstrator Board. With proper heatsinking of the Power MOSFETs and a well dimensioned power supply, the PWM amplifier is capable of supplying 200 W of high quality audio power into a 4 Ω loudspeaker.内容摘要：本用户手册描述了飞利浦半导体分立D类高功率音频放大器演示板的操作方法和最重要的背景资料。

在适当的功率管散热器的和很好的供电情况下，这台PWM放大器能提供200 W 高质量音频输出给一个4 Ω的扬声器。

1. Introduction简介The Universal Class D (UcD) version 1.00 demonstrator board implements a 200 W true RMS (into a 4 Ω load) high quality audio power amplifier on a very compact printed-circuit board. The amplifier is built-up of discrete components only, and makes use of Philips patent WO 03/090343.这个1.0版本的全D类功放(UcD)示范板是一个在非常紧凑的PCB板上输出200 W真有效功率(4 Ω负载)的高质量音频功放。

Fig 1. General view001aaf148 2. Circuit diagram电路原理图The demonstrator board is intended to illustrate the capability of Philips Power MOSFETs in discrete high-end PWM audio amplifier applications. The board is self-contained and only requires a simple (non-stabilized) dual power supply, an audio source (e.g. function generator, CD player) and a loudspeaker to demonstrate its capabilities. For evaluation at high output power a provision is made to attach an appropriate heatsink to the MOSFETs on the board.本演示板意欲图解说明飞利浦功率MOSFET在分立高档PWM音频放大器上的应用能力。

本板自我包含了齐全的功能，只需要简单的正负电源（非稳压），加上音源和扬声器即可示范其性能。

为评价在大功率下的性能，需要附上一个适当的散热片到MOSFET上。

Table 1. Connections 表一：连接器ConnectorFunction Remarks J1audio in - signal use together with J2 J2audio in - ground use together with J1 J3amplifier enable the amplifier is enabled when connected to ground (J4) J4ground use together with J3 J5 positive supply voltage 30 V to 45 V (no need for astabilized power supply)J6 positive current sense can optionally be used in anovercurrent protection schemeJ7 power supply ground 0 VJ8 negative current sense can optionally be used in anovercurrent protection schemeJ9 negative supply voltage −30 V to −45 V (no need for astabilized power supply)J10 loudspeaker output use together with J11J11 loudspeaker ground use together with J10J1 和J2用于音频输入；J3 和J4用于控制功放是否启用；J5 和J9是30 V 至45 V 正负供电，不需稳压； J6 和J8是电流感应端，用于设计功放保护；J7是电源的地；J10 和J11是输出端，用于接扬声器。

译者为了说明电路工作原理，作了一个示意原理图，参见左图：运放输出的信号经28uH 电感和680nF 电容后有延迟，对某些频率来讲，延迟的时间正好使信号反相，这个信号反馈到运放的负输入端，与其它元件配合，即形成一个400kHz 的方波振荡器，且运放正输入端的音频能调制这个振荡器，从运放输出输出一个PWM 信号，经28uH 电感和680nF 电容滤波后送给扬声器放大了的模拟音频功率信号。

译者认为，原作者的这个电路的确非常巧妙。

001aaf150 001aaf151Fig 3. Top copper layout Fig 4. Bottom copper layout001aaf152 001aaf153Fig 5. Component layout Fig 6. Top silk-screenTable 2. SpecificationsSymbol Parameter Conditions ValueV P supply voltage equal positive and negativesupply voltages±30 V to ±45 V P Loutput power V P = ±45 V; R L = 4 Ω;appropriate heatsink needed200 W (RMS) η efficiency P L = 100 W; R L = 4 Ω > 92 %THD+N total harmonicdistortion-plus-noise P L = 10 W; frequency rangefrom 20 Hz to 20 kHz< 0.03 %S/N signal-to-noise ratio > 120 dBf PWM PWM frequency idle ~ 400 kHzV offset offset voltage DC value < 50 mV4.1 Pop-less/click-less startup and shutdown功放上电和关机时防止“噗、噗”声和“喀、喀”声A provision has been added to the circuit to provide pop-less/click-less startup and shutdown. To make use of the startup facility, make sure that the supply power (pins J5 and J9) is applied prior to enabling the amplifier (connecting J3 to J4). To benefit from the pop-less shutdown feature, disable the amplifier (disconnect J3 and J4) prior to removing the supply power.电路预备了一个在功放上电和关机时防止出现“噗、噗”声和“喀、喀”声的功能。

开机上电时，令电源（J5和J9）提前于功放控制信号（J3和J4）；关机时则先断开J3、J4，后切断电源J5和J9。

4.2 Overcurrent protection 过流保护A provision has been added to the circuit to monitor the current flowing through the Power MOSFETs (Q13 and Q14). The voltage appearing between pins J5 and J6 is proportional to the current in MOSFET Q14 (ratio: 50 mV/A) and the voltage between J8 and J9 is proportional to the current in MOSFET Q13 (ratio: 50 mV/A). With the use of an external circuit these two signals may be used to disable the amplifier (disconnect J3 and J4) in case of an overcurrent situation. Similarly the J3-J4 pin combination can be used to disable the amplifier in case of other fault conditions.电路预备了一个监视功率管(Q13和Q14)电流的功能。