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[Previous] [Up] [Top] [Contents] [Back]3.2 Group Description
Figure 3-2
shows a function diagram of the input circuit for each group on the CC433.
Figure 3-2 Group Input Circuit
The input signals are passed via a D25 male connector to the CC433. Each D25 connector receives the signals for three channels. Opto-couplers are used for galvanic isolation between the differential signals and the system. Each opto-coupler input circuit meets the requirements of the RS-422-A standard and converts the differential input signal to a standard TTL signal. The 'minus' input can be connected to ground, to let the 'plus' input accept a single ended input signal.
Figure 3-3 Input Signal Termination
All input signals are received using the circuit as depicted in Figure 3-3. The combination of the parallel resistors, diodes and the series capacitor give an input impedance that approximates a nominal termination value of 120 Ohm. Differential input signals are properly terminated by this input circuitry and no additional termination is required.
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