1.
Datasheet provides amplifier performance when VSUPPLY equals to either 12.5V or 13.6V as shown in Figures 12..16.
VBIAS should be tuned to set required quiescent current. Datasheet provides performance for IDQ(A+B)=500mA.
Actual bias voltage can vary from device to device and on the required quiescent current. It will be above the threshold voltage that is specified as [1.7min;2.1typ;2.5max]V.
2.
Amplifier requires cooling: heat sink and/or fan.
Power efficiency is about 70% at maximum power. The dissipation power is 75W*(1/70%-1) = 32W. To keep case temperature below 80'C, the thermal resistance of the heat sink should be less than (80'C max -30'C ambient)/32W = 1.5'C/W.
Passive heat sink can be used as well, but it's size is determined by required thermal resistance. Rough estimation is 500-800 cm^3 per 1'C/W. So, a passive heat sink volume should be at least 340-540 cm^3. For example, 10cm*10cm*5cm.Have a great day,
Pavel
TIC
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