Power ON latch Up

Hi Robert,

When the deivce shuts down, does the FAULT pin go HI? You have the MUTE pin set to Low and not floating right? What is your load and output filter?

reg,

Paul.

Hi Paul
 
The FAULT pin is always LOW. The mute signal is forced LOW by optocoupler (the amp must stay isolated from rest of circuit). The speaker is 4 Ohm nominal but the termal resistance is about 4.5 Ohm. Because of requieremnts of limited bandwith the filter are set as 18 uH and  capacitor 20uF X7R ceramic on both output respectively. The BSP and BSN capacitors are 270nF X7R and the Cap-Res from OUT P&N to GND are 1nF and 22.1 Ohm.
I never observed that FAULT pin goes HIGH.
Regards
Robert

Hi Robert,

I would suggest that you try out the EVM and see if you can observe any differences between your design and the EVM. You can try to measure the voltage on the VBYP pin. If the device is in shut down mode, the voltage on VBYP will be 0V. However, if the device is in MUTE, it will be around 1.4V.  Also what may help is take a look at the PVcc supply on a oscilloscope during power up to ensure the quality of the power supply.

reg,

Paul.