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Q: TPA2051D3[audio subsystem] POP UP noise due to DC ABB
Dear TI experts.
I need your technical support on this.
when direct AB class amp is activating, if input signal like as turn on glitch implement to amp input stage, Can DC offset of AMP be changed ? Customer is hearing a pop when device turns on. After about 40ms of TPA2051 HP AMP Enable, Pop noise is heard. I know Input source(Baseband output) caused pop noise, but the DC offset level is changing too. Can a baseband pop cause DC offset to change? How can it be cured?
A: Re: TPA2051D3[audio subsystem] POP UP noise due to DC offset transition by input signal like as turn on glitch
An impulse at the input of the device should not change the DC offset of the device. However, changing the operating mode of the TPA2051D3 could change the DC offset of the the output. Is the customer changing the Input Mode (I2C register 0x04) when the pop occurs? This could explain the change in DC offset.
One way to verify that only the baseband is causing the pop is to have the customer run the startup procedure with the baseband disconnected or turned off. If the pop is still present, then it could be the TPA2051D3 I2C startup procedure causing the pop.
If the customer is changing the operating mode of the deivce, please ensure that they are following the recommended device operation to minimize pop/click as follows:
- Switching to active mode from software shutdownFirst, turn the device on in Mono ModeThen go to MUTE modeThen go to desired mode (such as Stereo SE Chan 1)
- Switching between modesFirst, go to MUTEThen, go to desired mode
Please ensure the customer is following the recommended I2C procedure and let me know if this cures the pop.
If the problem is truly only due to the baseband there are two software fixes that could be implemented:
1) Add a delay to the TPA2051D3 startup and do not enable the circuit until the 2nd baseband pop has occurred
2) Start up the TPA2051D3 with minimal gain until the 2nd baseband pop has occurred and then increase the gain on the TPA2051D3.
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