TLV320ADC6140: Not able to read DC signal

Part Number: TLV320ADC6140

We have been able to successfully read AC signals using TLV320ADC6140 but we are having trouble reading the DC signal.

We changed the channel register settings from AC coupled to DC coupled. When we read the signal we get a DC signal centered around 0V. Somehow the DC bias/offset is being removed eventhough the settings has been done for DC coupling.

We want to use one out of four channels of TLV320ADC6140 for reading DC voltage. Currently we are using Channel 3 for this purpose.

Register setting pertaining to Channel 3:

Register 0x46 - 0b00110000  (mic Input, Analog Single ended, DC-coupled, Impedence = 2.5kohm)

Register 0x47 - 0b00000000 (Gain - 0dB)

Register 0x48 - 0b11001001 (Digital Volume Control - 0dB)

Register 0x49 - 0b10000000 (Gain Calibration - 0dB)

Register 0x4A - 0b00000000 (No phase calibration)

Are there any other changes which need to be made to read the DC signal?

  • Hi Rohan,

    The ADC6140 also has a high pass filter that is applied to all channels and is set to 0.00025*fs by default. You will want to change this to the custom HPF filter setting which is configured as all-pass by default.