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6.1.2 AUX Input
In its basic input mode, the AUX input allows an external input source to be detected by the
IQ software. This input can be a temperature sensor, door closure switch, or operator push-
button. It can be used by the IQ software to change configuration settings on any or all sys-
tem devices. See System AUX and Scenes in the IQ System Help files.
Pin 5 of the AUX input is a power-supply pin designed for use by the AUX input pin. Since
the AUX input floats low, the AUX input can be triggered by just a simple switch closure
between it and the AUX power pin. No external power supply is needed to operate the AUX
input under most conditions. If the AUX input is used to sense a externally supplied voltage
it must be scaled so that low inputs are between 0 and 1.6 VDC, and high inputs are
between 4 and 15 VDC. Externally supplied voltages should be referenced to AUX ground
on pin 3.
The AUX input features seven enhanced modes. The first six modes allow the AUX input to
mute or power-down either or both channels. The AUX Input Inversion Control allows either
a high or low AUX input to activate these functions. These modes can be used for emer-
gency shutdown for a fire alarm system. A simple switch closure from the alarm system
would disable an entire sound system when a fire alarm is activated.
6.2 Load Supervision Applications
The IQ-PIP-USP3/CN Load Supervision feature can be used to monitor the amplifier load
in real time with almost any program material. Average load impedance is calculated as a
function of amplifier output voltage and current. The system requires approximately 20-30
mA of average amplifier output current for adequate supervision. This allows typically low
average output power levels of less than ½ watt with most loads. The maximum load
impedance for reliable system performance is limited to about 50 ohms. Higher imped-
ances can be measured but may require higher amplifier output levels for reliable opera-
tion.
Most amplifier/load systems can be configured and supervised by following these steps:
1. Configure your audio system using a known "good" load, then enable the Load Supervi-
sion feature.
2. Provide typical program material at a level high enough to light the "test" indicator.
3. Run the system at this level until the average impedance stabilizes. This may take sec-
onds to minutes depending on level, duty-cycle, etc.
4. Set the nominal impedance at the measured value average. This optimizes the supervi-
sion algorithm for voltage and current levels versus the actual load. Note: a higher nom-
inal setting will require higher output levels.
5. Set the high limit at twice average and the low limit at one-fourth nominal. (These limits
are somewhat arbitrary but should be a good starting point.)
6. Let the system run for extended periods using any and all typical program material.
7. Adjust the high/low limits, if necessary, to account for any variance in average measured
impedance.
8. Enable error reporting, if desired.
page 38
IQ-PIP-USP3/CN
Reference Manual
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