Over Voltage Protection

Over Voltage Protection shuts down the amplifier if the bus voltage between –Vcc and +Vcc

exceeds 126V, the threshold is determined by the sum of the zener voltages of Z1, Z2, and Z3.

OVP protects the board from the bus pumping phenomena which occurs at very low audio signal

frequencies by shutting down the amplifier.

Power On/Off Sequence Timing

The IRAUDAMP1 is a robust design that can handle any power up/down sequence. However,

symmetrical power up is recommended to properly initiate the self oscillation. In order for the unit

to startup correctly, the negative power supply has to be initialized from zero volts.

Fig.5 shows a preferred power up sequence. At start-up, a DC output voltage appears at the

output of the LPF due to the charging of the bootstrap capacitors. To avoid this unwanted DC

output signal being to fed to the load, the output relay RLY1 engages approximately 2 seconds

after the startup condition is completed. Fig 6 below shows the start-up timing with the audio

output not being activated until approximately 2 seconds after the power supplies are stable and

the amplifier has reached steady state operation.

Fig.5 Start-up Timing

(BLU: Switching, RED: Audio Output)

www.irf.com

9