ST TS4961T带专用模拟开关D类放大方案

ST公司的TS4961T是带有专用模拟SPST开关的D类音频功率放大器,工作电压2.4V到4.3V, 在THD+N为1%时能向4欧姆负载提供1.6W,向8欧姆负载提供0.95W功率,效率可高达88%,信噪比为85dB. 20 Hz 到20 kHz的模拟开关的隔离度为-80dB. TS4961T广泛用在蜂窝手机,PDA和笔记本电脑.本文介绍了TS4961T的主要特性, 音频放大器和PSRR的测试电路, 典型应用电路, 单端输入应用电路, 多个单端输入应用电路, 双差分输入应用电路以及一个差分输入和一个单端输入应用电路.

TS4961T: Mono class D audio power amplifier with dedicated analog switch

The TS4961T is a smart combination of one mono class D audio power amplifier and a
high-speed CMOS low-voltage dual power analog SPST.

One of the key functions of this device is the switch mode of the various audio signals coming
from the codec or baseband through the loudspeaker. It can drive up to 1.6 W into a 4 ohm
load and 0.95 W into an 8 ohm load. It achieves an outstanding efficiency of up to 88% typical.

The audio amplifying gain of the device can be controlled via two external gain-setting resistors. It is designed to operate from 2.4 to 4.3 V, making this device ideal for portable applications.

TS4961T主要特性:
■Wide operating voltage range from VCC = 2.4 V to 4.3 V
■Audio amplifier standby mode active low
■Output power: 1.6 W at 4.2 V or 0.75 W at 3.0 V into 4 ohm with 1% THD+N maximum
■Output power: 0.95 W at 4.2 V or 0.45 W at 3.0 V into 8 ohm with 1% THD+N maximum
■Adjustable gain via external resistors
■Low current consumption 2 mA at 3 V
■Efficiency: 88% typical
■Signal-to-noise ratio: 85 dB typical
■PSRR: 63 dB typical at 217 Hz with 6 dB gain
■PWM base frequency: 250 kHz
■Low pop and click noise
■Dual Power SPST with separated control
■Ultra-high off-isolation on analog switch: -80 dB typical from 20 Hz to 20 kHz

TS4961T 应用:
■Cellular telephones
■PDAs
■Notebook PCs



图1.TS4961T音频放大器测试电路



图2.TS4961T音频放大器PSRR测试电路



图3.TS4961T典型应用电路



图4.TS4961T单端输入应用电路



图5.TS4961T多个单端输入应用电路



图6.TS4961T双差分输入应用电路



图7.TS4961T一个差分输入和一个单端输入应用电路



图8.TS4961T典型应用电路