Hello,

I'm setting up a system with a STA309A DSP and a STA510A amplifier.

I'm expecting to connect two 8Ω loads with a maximum power of 50W each, but I can't find the graphics that show the estimated Power dissipation and the THD that I can expect at that level. The datasheet for other parts like the STA518A do have figures that allow me to calculate that.

Is there an application note that describes how to calculate the required power supply for a specific power output?

I'm setting up a system with a STA309A DSP and a STA510A amplifier.

I'm expecting to connect two 8Ω loads with a maximum power of 50W each, but I can't find the graphics that show the estimated Power dissipation and the THD that I can expect at that level. The datasheet for other parts like the STA518A do have figures that allow me to calculate that.

Is there an application note that describes how to calculate the required power supply for a specific power output?

sorry, the applicaiton note is not available in ST website , but you can calculate it by following equation :

I peak = Vcc*MI/(Rload+2*Rdson) ---- for BTL , current will go through two mosfet , MI is modulation index , for STA309A , it would be 94% for calculation . for STA510A or STA518 , Rdson is 0.2.

P @ 1% THD =1/2 *((I peak)^2)*R load

P @ 10% THD = 1.28 * P@ 1% THD .

then for your applicaiton , if 50W output is for 10% THD , then the unclipping output would be 39W =( 50/1.28) , and the max peak current through 8 ohm load would be 3.125A .

so the Vcc (supply voltage ) would be 27.9V = ( 3.125 *8.4/0.94).

considering the tolerance and loss in coil and trace , 28.5V would be enough for your target output power .

Thanks ,

YT