Voltage waveforms duty cycle

The presently selected part is VJTL, which was created for this textbook to generate a TTL-compatible waveform (0 to 5 V) with a specified duty cycle and frequency. We wish to select a generic DC voltage supply. Type the text dc to complete the typing of vdc and select the part ... 

Figure 8.16 Node 10 voltage waveform with high voltage, low voltage, duty cycle, and frequency measurements.

Note also that the duty cycle of such a forward converter can under no circumstances ever be allowed to exceed 50%. The reason for that is we have to unconditionally ensure that transformer reset will always occur, every cycle. Since we have no direct control on the transformer current waveforms, we have to just leave enough time for the current in the tertiary winding to ramp down to zero on its own. In other words, we have to allow voltseconds balance to occur naturally in the transformer. However, because the number of turns in the tertiary winding is equal to the primary turns, the voltage across the tertiary winding is equal to Vin when the switch is ON, and is also equal to Vin (opposite direction) when the switch is OFF. Reset will therefore occur when toFF becomes equal to toN- So, if the duty cycle exceeds 50%, toN would certainly always exceed toFF, and therefore transformer reset would never be able to occur. That would eventually destroy the switch. Therefore, just to allow toFF to be large enough, the duty cycle must always be kept to less than 50%. 

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