there is a problem, TLV320ADC5120, differential input, input impedance set to 2.5K. About 15PCS of PCBA were used in the same batch. The test found that about half of the platforms were noisy (about 0.8mV for the whole system test), while the platforms with normal noise were only about 0.2mV. Have you ever encountered such a situation? Is it related to software Settings? Have done a test: 1, with AP connected to I2S test, chip SNR about 104dB. 2, the input end is directly grounded through the capacitor, and the system output noise (0.8mV) does not change. 3. After replacing the new chip, this noise problem can be solved.
Here is the schematic diagram:
