ST TS472非常低噪音麦克风前置放大方案

ST 公司的TS472是非常低噪音麦克风前置放大器,全差分输入/输出, F = 1 kHz时输入等效噪音为10 nV/√Hz,单电源2.2V-5.5V工作,典型失真为0.1%,主要用在视频照相机声音输入,声音采集和语音识别,视频会议系统,笔记本电脑和PDA.本文介绍TS472主要特性,典型应用电路,单端输入应用电路和演示板STEVAL-CCA023V1主要特性与电路图.

Very low noise microphone preamplifier with 2.0 V bias output and active low standby mode The TS472 is a differential-input microphone preamplifier optimized for high-performance PDA and notebook audio systems.

This device features an adjustable gain from 0 to 40 dB with excellent power-supply and commonmode rejection ratios. In addition, the TS472 has a very low noise microphone bias generator of 2 V.

It also includes a complete shutdown function, with active low standby mode.

TS472主要特性:

■ Low noise: 10 nV/√Hz typ. equivalent input noise at F = 1 kHz

■ Fully-differential input/output

■ 2.2 to 5.5 V single supply operation

■ Low power consumption at 20 dB: 1.8 mA

■ Fast start up time at 0 dB: 5 ms typ.

■ Low distortion: 0.1% typ.

■ 40 kHz bandwidth regardless of the gain

■ Active low standby mode function (1 uA max)

■ Low noise 2.0 V microphone bias output

■ Available in flip-chip lead-free package and in QFN24 4 x 4 mm package

■ ESD protection (2 kV)

TS472应用:

■ Video and photo cameras with sound input

■ Sound acquisition and voice recognition

■ Video conference systems

■ Notebook computers and PDAs


图1.TS472应用电路

图2.TS472典型单端输入应用电路

演示板STEVAL-CCA023V1

Demonstration board for low noise microphone preamplifier with 2 V bias based on the TS472 The STEVAL-CCA023V1 demonstration board is designed as an evaluation platform for the TS472 low noise microphone preamplifier with 2.0 V bias and active low standby mode.

The board supports customization of the testing conditions, allowing the gain of the TS472 device to be adjusted, or an electret microphone to be biased either externally or using the TS472 builtin 2.0 V bias voltage.

演示板STEVAL-CCA023V1主要特性:

■ Low noise: 10 nV / √Hz typ. equivalent input noise @ F=1 kHz

■ Fully differential input/output

■ 2.2 V to 5.5 V single supply operation

■ Low power consumption @20 dB: 1.8 mA

■ Fast start up time @ 0dB: 5 ms typ.

■ Low distortion: 0.1% typ.

■ 40 kHz bandwidth @ -3 dB and adjustable gain

■ Active low standby mode function (1μA max)

■ Low noise 2.0 V microphone bias output

■ Available in flip-chip ECOPACK® package and QFN24 4x4 mm

■ ESD protection (2 kV)

■ RoHS compliant

图3. 演示板STEVAL-CCA023V1外形图

图4. 演示板STEVAL-CCA023V1电路图