I am using a Sure-Electronics 2x50W Class D amplifier board based on the TPA3116D2. I am driving two 4 ohm full range speakers in separate enclosures. The amp works at low input signal voltage, but as soon as I pick the input voltage up to about 150mvrms, the FAULT circuit fires, and the amp quits for several seconds and then recovers only to FAULT again in another few seconds. I know the FAULT circuit is firing because it is connected directly to the STBY pin on the board, and the voltage on it goes low when the FAULT occurs.
The amp does this regardless of the power supply. I have tried a lab power supply and a 12v lithium battery.
With my lab power supply set to 24v, I show a total current draw of about 400mA when the FAULT kicks in. That is only 9.6W. If the amp is 90% efficient, the output can't be over 8.5W. I should be able to get close to 50W at that voltage.
Maybe someone here that has experience with this amp might know what is causing the fault.
The amp does this regardless of the power supply. I have tried a lab power supply and a 12v lithium battery.
With my lab power supply set to 24v, I show a total current draw of about 400mA when the FAULT kicks in. That is only 9.6W. If the amp is 90% efficient, the output can't be over 8.5W. I should be able to get close to 50W at that voltage.
Maybe someone here that has experience with this amp might know what is causing the fault.
These amps are rated 4 ohms in BTL and 2 ohms on PBTL. I don't think that is the problem. It may be a bad bootstrap cap that breaks down when voltage is too high. A bad (cold) solder connection on the output pin from the IC to the inductor can also cause cutout as current kicks in, it goes bad. Also check to see if you have any bad input caps (shorted), or bad main power rail caps. Only a few things that cause the TPA3116 to shutdown: overheat, bad bootstrap cap, bad input cap, bad power rail cap.
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