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Random TLV320AIC3256 Microphone hangs when Mic plug in

INg
Genius 3475 points
Other Parts Discussed in Thread: TLV320AIC3256

HI 

Would like to seek some advise on how to improve the situation I am facing below

I am using a Mic(single ended - peak 100mV) to input into the TLV320AIC3256, there are random occurrences when the port appears Hang.

Hang - as in the

  • output of the ADC register read back is at a certain DC value which does not response to additional signal generated from the MIC. It remains at a certain DC value. 
  • The measured mic bias is 0V and remains so upon hang

In a good connection

  • output of the ADC register read back is of lower value than above but this register is responding to external mic stimulus
  • The MEasure Mic bias is at 0.75V

One possible recovery is a hardware reset or a software reset using below 

0x0.1 1'              ;Set to page 1

0x34.1 0x00'     ;Left MICPGA routing not routed

0x36.1 0x00'     ;Left MICPGA routing not routed

0x34.1 0x10'     ;Left MICPGA routing with 10K resistance input +ve

0x36.1 0x10'     ;Left MICPGA routing with 10K resistance input -ve

0x37.1 0x00'     ;Right MICPGA routing not routed

0x39.1 0x00'     ;Right MICPGA routing not routed

0x37.1 0x40'     ;Right MICPGA routing with 10K resistance input +ve

0x39.1 0x10'     ;Right MICPGA routing with 10K resistance input –ve

 

As the above Hang phenomenon is random, one suspect is transient voltage as the MIC is self powered.

Woudl like to check if there is any work around using existing on silicon feature?

Or s there any recommended protection circuit for transient voltage?

Ivan 

  • 0
    TI__Guru**** 189401 points

    Hi, Ivan,

    I have asked my colleague to work with you on this issue.

    -d2

  • 0
    TI__Mastermind 46195 points

    Hi Ivan,

    Two things:

    1. For differential configuration, make sure the input power-up time is configured as follows:

    # Select Page 1
w 30 00 01
#
# Set the input power-up time to 3.1ms (for ADC)
w 30 47 32
#
# Set the REF charging time to 40ms
w 30 7b 01

    2. Ensure voltage at the pin does not exceed the range [0V, 1.8V}. If this is causing an issue, consider using two diodes with low Vf (e.g. 0.3V), one with anode connected to gnd, cathode to pin and another with anode connected to pin, cathode to avdd.

    Regards,

    J-