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DPC31 HW

Page 58 Version V 1.0

DPC31 HW Description

signal (TxS1) is assigned a long pulse and the falling edge is assigned a short pulse. Likewise with the

edges of the static auxiliary signal (TxE1 or RTS/ADD), a long and short pulse is generated which are added

to the pulse sequence of the data signal. The summation signal thus generated (TxS_IM) is used for

sampling the LED of an optocoupler.

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Figure 7.5-8: Signal Shaping in the Modulator

Pulse Duration Demodulator:

In the galvanic isolation mode (GIM_EN=’1’), the useful signal for the PDM is recovered from the collector

signal of the optocoupler transistors by using a comparator.

The following digital circuit component (integrated into the DPC31) evaluates the length of the output pulses

of the comparator and recovers from it the data signal and the auxiliary signal. The circuit diagram of the

demodulator is shown in Figure 7.5-9. The signal characteristic with respect to time is shown in Figure 7.5-

10.

When using RxS_IM, the pin RxA is to be applied to GND.

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