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TAS2505: HP Pop noise

Part Number: TAS2505

Hi Expert,

Used the EVM and datasheet setting, it can get a big pop when set the unmute, whatever change the P1 0x14, can't get the good result.

1. slau472.pdf page50 4.0.8 setting.

2. Adjust the P1 0x14.

W 30 00 00
# Assert Software reset (P0, R1, D0=1)
W 30 01 01
# Page Switch to Page 1
W 30 00 01
# LDO output programmed as 1.8V and Level shifters powered up. (P1, R2, D5-D4=00, D3=0)
W 30 02 00
# Master Reference Powered on (P1, R1, D4=1)
W 30 01 10
# Enable AINL and AINR (P1, R9, D1-D0=11)
w 30 09 03
# AINL/R to HP driver not via Mixer P (P1, R12, D1-D0=11)
w 30 0C 03
# HP Voulme, 0dB Gain (P1, R22, D6-D0=0000000)
W 30 16 00
# Not enable HP Out Mixer, AINL Voulme, 0dB Gain (P1, R24, D7=0, D6-D0=0000000)
W 30 18 00
# Enable AINL and AINR and Power up HP (P1, R9, D5=1, D1-D0=11)
w 30 09 23
# Unmute HP with 0dB gain (P1, R16, D4=1)
w 30 10 7a
w 30 0a 40
w 30 14 54
d 100
w 30 10 00

It can reduce the pop level, but still can hear that. Whatever how to adjust it, we can get the sharp voltage to DC offset, how to adjust it to smooth? Can you provide the EVM setting to me? Or it's IC limitation? Thanks!

  • Hi Jerry,

    The headphone driver of this device is centered to a common mode voltage (not GND) so pop could occur at startup.
    What is the impedance of the load you're using?

    I'll run some tests on the EVM to see how pop can be reduced/eliminated and what would be the minimum load impedance for that.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • Hi Ivan,
    Thanks, the headphone impedance is 40ohm. I know it's not direct path architecture, but the customer can't accept the pop issue and told me that other solution DC voltage can smooth ramp up to DC offset, won't get the pop issue. Why TAS2505 can't do it? Anyway looking forward your feedback. Thanks!
  • Jerry,

    Just wanted to give you an update on the current status of this test.
    I've verified on a EVM that the output is not charging up to bias voltage but stopping at midway. This causes that when the HP output is unmuted there is pop noise.
    I'm checking what could be causing this weak charging up of the HP driver output.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • Hi Ivan,
    Thanks for the update, if you have any good method can improve it, pls let me know.
  • Hi Ivan,
    Any update? Thanks!
  • Jerry,

    After several tests I found out that the bias of this device is not completely powered up until all the signal path is enabled, this is the reason why the bias is not charging up if HP driver is not unmuted.
    Unfortunately it seems that there is no way to charge the bias before enabling the output stage. After the output coupling capacitor, the pop will be seen as a brief transient. I apologize for not bringing an actual way to mitigate the transient at the analog output.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators