DMC-21x3 Accessories Chapter 3 ICM-20100• 17
Amplifier Enable
The standard configuration of the AMPEN signal is TTL active high. In other words, the AMPEN
signal will be high when the controller expects the amplifier to be enabled. The polarity and the
amplitude can be changed. To change the polarity from active high (5 volts= enable, zero volts =
disable) to active low (zero volts = enable, 5 volts= disable), replace the 7407 IC with a 7406
(U2). Note that many amplifiers designate the enable input as ‘inhibit’.
To change the voltage level of the AMPEN signal, note the state of the resistor pack on the ICM-
20100. When pin 1 of the resistor matches pin 1 of the RP1, the output voltage is 0-5 V. To
change to 12 volts, pull the resistor pack and rotate it so that pin 1 is on the 12 volt side. Pin 1 of
the resistor will be marked with a designator, pin 1 of location RP1 can be determined by the
square through hole on the circuit board denoting pin 1. If you remove the resistor pack, the
output signal is open collector, allowing the user to connect an external supply with voltages up to
24V. Note that any external pull-up resistor should limit the current draw to 10 mA
Figure
Figure 5 ICM-20100 Amplifier Enable Circuit
RP1
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