TPA3118 Mode Select and Shutdown Issue

Hi CG,

I would recommend BD mode.

What is the input circuit looks like? I wonder if the DC detect is being triggered during power up. The inputs (both positive and negative) need to have similar impedance to avoid a large DC offset at the input for long duration of time during start up. The DC offset can trigger DC detection to avoid speaker damage. You may want to probe the inputs and see if there is any large DC offset (offset spec to trigger DC detect is listed in the DS).

Also try remove the capacitors after the inductors (used for LF filter) and see if somehow there is too much current is going through them.

Does this issue only happen at startup? Do you have load connected to the outputs? Is the power supply voltage stable during startup and operation? What is the supply voltage? When SDZ is pulled low, does it auto-recover to normal operation?

reg,

Paul Chen

Audio Applications Engineer

Dallas TX

Thanks Paul.

I 've tried as below in BD mode with 4R load.

A. Removed the LC filter, the Fault still be triggered.

B. Connect the input signal to GND before the input capacitor, the Fault still be triggered.

C. When SDZ pulled low, it doesn't auo-recover.

I will get more boards tomorrow to test.

Hi CG,

When the device Fault is triggered it should try to auto-recover when FAULTZ is tied to SDZ. However, if the fault condition still exist the part will shutdown again. This start and stop will continue until the fault condition is removed. You should be able to see a small pulse on the outputs repetitively on the oscilloscope. Can you measure the timing (period) between the output pulse?

reg,

Paul.

Hi  Paul,

    Just as you mentioned,  here is the Fault Picture in BD mode when tied to SDZ.   And in SPW mode, it works normally.

Here is the LC Output Picture,