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Class AB power dissipation rises as amplifier output power increases, and peaks below maximum amplifier output power. Then it drops even though amplifier output power continues to increase. Class AB peak power dissipation occurs at 50% efficiency, when the amplifier output power is equal to the power dissipation. Peak power dissipation, PDMAX, for a mono, single-ended Class AB amplifi er is found using the derived formula:
PDMAX = (Total Supply Voltage)2 / (2π2RL) (Watts)
Th e amount of power dissipation is inversely proportional to the load impedance. If the load impedance is halved, the peak power dissipation doubles. The amount of power dissipation increases with the square of the supply voltage. Doubling the supply voltage will increase the peak power dissipation by four times.