Hello
My customer is using TAS5711 several years for thier product with BD mode.
A few weeks ago, customer informed me that around 10% of customr's product has
POP at the exit of shutdown in their production line.
Problem is just only POP at power on , and sound from speaker after Power on, is OK.
I'd attached the wave form.
90% of products using TAS5711 BD mode, is no problem, so we think this may be
any device failure.
In case customer had changed AD mode (0x05 D3=1) and,
then exit shutdown (0x05 D6=0 ), there are no POP,
but customer want to use BD mode because of audio fidelity.
I think there may be failure in the PWM section of the device, but customer found interesting solution.
Following is the procedue for fix the POP noise problem , which is tested
using TAS5711GDE and EVM ( remove the fail device from customer's PCB
then mounted to EVM)
----
1 POWER OFF
2 POWER ON DVDD
3 POWER ON PVDD
4 set AD mode, connect
5 exit shutdown in the GDE ---- no pop. PWM is in AD mode
6 disconnect
7 change BD mode
8 connect
9 shutdown assert in the GDE
10 exit shutdown in the GDE ---- no pop. PWM is BD mode ( in phase)
Note:
POWER is ON from 3 to 10.
If customer and I were start from 6,, POWER off/ then POWER on, then 7 set BD mode, 8 connect, and so on..,
there were POP.
-----
Q1
We believe the procedure avobe ( change AD to BD with keep power on ) has no problem
in the TAS5711 EVM evaluation,
but if you think there any problem in the above procedure, please adivice
about the correct way to change from AD to BD with keep the power on.
Q2
Customer think to enable Mid-Z ramp even BTL (BD) has slightly effective for
decrease of the POP reduction.
Do you think to be enable Mid-Z ramp in BTL (BD mode) is problem?
Because D/S says Mid-Z ramp is used for SE or 2.1ch.
With My Best Regards
