Part Number: SN74LVC1G3157
Other Parts Discussed in Thread: TS5A22364
您好，计划是用SN74LVC1G3157 用于音频信号切换，运放单电源5V供电，直流偏置为2.5V，有以下几个问题：
1、对于SN74LVC1G3157 应用电路有无问题？
2、SN74LVC1G3157 的引脚B1，B2，A需要使用 分压电阻进行构造2.5V，放置负半周失真？
3、如果避免SN74LVC1G3157 切换 时候有切换噪音？
4、SN74LVC1G3157 会自动产生偏置功能吗？
手册内有提到：“2 应用 • 可穿戴设备和移动设备 • 便携式计算 • 物联网（IoT） • 音频信号路由 • 远程无线电单元 • 便携式医疗设备 • 监控 • 家庭自动化 • I2C/SPI/UART 总线多路复用 • 无线充电” 音频信号路由。
我不知道你有没有实际测试过这个芯片？
AUDIO_B2 接入一个信号源（先把信号源输出调节到0V 1khz），然后通过示波器监测3157的输出引脚PIN4，当AUDIO_B2 为0V时候，PIN4为0V，当AUDIO_B2慢慢增大时候，PIN4也会增大，并且会产生一个直流偏置信号。真的很神奇？这是正确的？？
您好
I do see in the datasheet that it mentions audio signal routing and we can actually see if this device is good for this particular audio application.( Lets talk through this and we can determine more)
1.What your are describing is actually the normal function of a multiplexer. When you place a signal on one of its input pins that same signal will be passed through the device to the selected output pin
2. Can you tell me the voltage swing of the signal your are passing through the device( signal sent from source and placed on input pin)?( This device can pass signals from VCC to 0V on its io pins)( Passing a signal on this device from pin 1 to pin 4 is a normal operation for this device)
No DC bias should be generated here as this is a passive multiplexer device.( The signal you put on pin 1 should show up on pin4 with minimal signal distortion.
If you could tell me the voltage swing of the signal being passed through the mux and the frequency of that signal we can just verify if this device is good for you application
As along as the signal being passed swing is from 0V to VCC and the frequency is less than the bandwidth of 340MHz this device should be fine for this application.
非常感谢，您的回复!
按照您的方法， 我去掉了所有运放， 使用三个示波器探头， PN1 监测信号源输出，PIN2监测3157输入，PIN3监测3157输出，把所有外部因素全部去掉；测试后PIN1 是无直流偏置的，PIN2和PIN4 会根据信号大小产生偏置。我也非常奇怪？
