I am having an issue where the SN74121N device is initially outputting a HIGH when I start the simulation on an oscope. Here is how I expect the circuit to function:
1. Toggle the PRI_PWR_ON1 switch from LOW to HIGH
2. Enable the flip flop U11 to output a pulse to SN74121N.
3. The SN74121N outputs a 68ms pulse (Note* you need to toggle the ~CRL on the flip flop to be able to to switch PRI_PWR_ON1 again)
Everything is working as normal except when I start the simulation, the SN74121 outputs HIGH even though I did not toggle the PRI_PWR_ON1 switch. I have already verified that the high pulse is not coming from devices before the SN74121N. So the high pulse is somehow preset to be high when I start the simulation. I have attached the simulation and a screenshot of the schematic. Any help will be much appreciated!