We are using the TAS5630 Amplifier in a BTL configuration to drive one 100 Ohm load at 25 VRMS with a 42 Vdc power supply. The other BTL output is not connected to a load.
According the Class D LP Filter Design formulas, the output inductors should be in the range of 233uH for a 100 Ohm load. The filter caps are currently 0.033uF metal film 100 Vdc parts.
The amplifier seems to drive the load with these components installed with very little distortion at 25 VRMS as desired, but the TAS5630 Chip runs very hot and will eventually hit the 125 degree shut down point. With the original inductors and caps, (15uH and 0.68uF) the TAS5630 IC driving the the same load at the same 25VRMS voltage, the temp rise is almost all the result of the normal operating power in the TAS5630 IC. (IC temp settles around 57 degrees C.) When the 100 ohm load driven at 25 VRMS is attached with the original components, the IC temp only increases another 10 degrees. (67 degrees C). All temperatures are measured on the top thermal pad of the TAS5630 IC with no heat sink.
The Coilcraft MSS1260 250uH inductors have a rated current of 1.0 Adc and a saturation current of 1.5 Adc.
What is causing the IC to heat up so much when I change the inductor values from 15uH to 220uH and the caps from 0.68uF to 0.033uF??
FYI, the installed filter components are to big to fit in our current design space. We only need to drive 25VRMS into an 8 Watt load.
Thank You