Crown Audio IQ-PIP-USP2_CN - Manual (Page 52)

IQ-PIP-USP2/CN
Page 52 IQ-PIP-USP2/CN Reference Manual
* A negative signal can also be used as
a logic low because the signal is inter-
nally clamped to protect the internal
circuitry.
10.5.2 AUX Input
The AUX connector can be used to
sense the presence of an input sig-
nal across pins 2 (+) and 5 (ground).
Like the AUX Output, the AUX Input
polarity can be set to either invert-
ing or non-inverting. When set to
non-inverting, a +5 to +35 VDC sig-
nal at the input is interpreted as a
logic “high” and a signal less than
+1.6 VDC is interpreted as a logic
“low.”* The AUX Input will act on the
received signals depending upon
the AUX Input operating mode se-
lected (see Section 9.4).
Figure 10.13
A Sample AUX Output Circuit
10.6 Load Supervision
Applications
The IQ-PIP-USP2/CN Load Supervi-
sion feature can be used to monitor
the amplifier load in real time with
almost any program material. Aver-
age load impedance is calculated
as a function of amplifier output volt-
age and current. The system re-
quires 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 imped-
ance for reliable system perfor-
mance is limited to about 50 ohms.
Higher impedances can be mea-
sured but may require higher ampli-
fier output levels for reliable opera-
tion. Most amplifier/load systems can be
configured and supervised by fol-
lowing these steps:
1. Configure your audio system
using a known “good” load, then
enable the Load Supervision
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 seconds
to minutes depending on level,
duty-cycle, etc.
4. Set the nominal impedance at the
measured value average. This