TPA3112与麦克风的连接

TPA3112 这个器件的性能很好的. 不过从手册看, 输入端有个阻抗匹配方面的要求. 要留意一下

Gain setting via GAIN0 and GAIN1 inputsThe gain of the TPA3112D1 is set by two input terminals, GAIN0 and GAIN1. The voltage slew rate of these gain terminals, along with terminals 1 and 14, must be restricted to no more than 10V/ms. For higher slew rates, use a 100kΩ resistor in series with the terminals.The gains listed in Table 1 are realized by changing the taps on the input resistors inside the amplifier. This causes the input impedance (ZI ) to be dependent on the gain setting. The actual gain settings are controlled by ratios of resistors, so the gain variation from part-to-part is small. However, the input impedance from part-to-part at the same gain may shift by ±20% due to shifts in the actual resistance of the input resistors.For design purposes, the input network (discussed in the next section) should be designed assuming an input impedance of 7.2 kΩ, which is the absolute minimum input impedance of the TPA3112D1. At the lower gain settings, the input impedance could increase as high as 72 kΩ

TPA3112本身就是驱动芯片，输出推动扬声器不需要再加驱动电路。具体的电路你可以参考该芯片的EVM板

在正常工作的情况下，fault与SD不短接的话，fault应该为高电平还是低电平？？？

那它可以直接与麦克风连接吗？？信号会不会太小？？？

TPA3112的fault引脚是漏极开路型的，使用时不与SD短接时需要外接上拉电阻，正常情况下输出高电平

与麦克风直接连接需要外接前置放大电路，但是用低通就行了吧一般，没必要用带通滤波器吧

fault与SD都需要接上拉电阻吗？

这两个引脚同时上拉到1个100K的电阻即可。SD手册上并没有说它是OC或者OD门，但是应用时最好加一个上拉

你好，

TPA3112是模拟输入音频功率放大芯片，在你的应用中是麦克风输出信号直接送到功率放大级对吗？

如果是这样是没有问题的，需要注意麦克风输出是单端还是差分，与TPA31112之间采用交流耦合。

对于TPA3112来说，SD pin与Fault直接连接是为了在输出短路解除时从shut down状态自动恢复。