Problem description: Turn on the 48V DC phantom power supply of the MIC input interface (the current sensitivity is -56dBu, and the problem still exists at other low sensitivities). When the interface is plugged and unplugged, an abnormal sound will be output;
Problem analysis: At the moment of plugging and unplugging, a high peak voltage will be generated. When input to the VIN interface of PCM3168A (VIN adopts differential input), the peak voltage of the P and N single lines reaches 2.8V. According to the single line of PCM3168A at differential input The maximum input amplitude is 1Vrms, and the maximum input peak value can only reach 1.414V. The peak voltage is too high, causing oscillation at the output end and abnormal sound output;
Questions we hope to solve: 1. What is the processing mechanism for transient abnormal voltages exceeding the limit value?
2. Is there a better way to solve this problem?
3. How to use the chip pin OVF (5th pin)?
See the attachment for the oscilloscope test waveform and unplugging sound.
