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Page 22 of 50
IRAUDAMP5 REV 3.1
3.
Smaller bus capacitors (the same energy will cause a larger voltage increase)
The IRAUDAMP5 has protection features that will shut down the switching operation if the bus
voltage becomes too high (>40V) or too low (<20V). One of the easiest countermeasures is to
drive both of the channels in a stereo configuration out of phase so that one channel consumes the
energy flow from the other and does not return it to the power supply. Bus voltage detection is
only done on the –B supply, as the effect of the bus pumping on the supplies is assumed to be
symmetrical in amplitude (although opposite in phase) with the +B supply.
Bus Pumping Figure:
Cyan = Positive Rail voltage (+B)
Green = Speaker Output
Pink = Negative Rail voltage (-B)
Fig 24
Input Signal
A proper input signal is an analog signal below 20 kHz, up to ±3.5V peak, having a source
impedance of less than 600 ohms. A 30-60 kHz input signal can cause LC resonance in the output
LPF, resulting in an abnormally large amount of reactive current flowing through the switching
stage (especially at 8 ohms or higher impedance towards open load), and causing OCP activation.
The IRAUDAMP5 has an RC network (Fig25), or Zobel network (R47 and C25 [CH1]), to
dampen the resonance and protect the board in such an event, but is not thermally rated to handle
continuous supersonic frequencies.
These supersonic input frequencies therefore should be
avoided.
Separate mono RCA connectors provide input to each of the two channels. Although
both channels share a common ground, it is necessary to connect each channel separately to limit
noise and crosstalk between channels.
Summary of Contents for IRAUDAMP5
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