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I am trying to simulated in pspice a soft latch on/off circuit but it is not working as expected, even if I double check the implementation. Can someone explain to me why the voltage on the probe is 0.6 V even if the circuit has no "ON" button attached to it in this moment? I supposed to be off since the gate of PMOSFET should be high but it is not. I am almost sure that I did something wrong in the simulation.

enter image description here Thank you!

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  • \$\begingroup\$ Maybe your initial conditions, try applying power to the circuit with a pulse source a microsecond after the simulation starts or play with the options for cap and voltage initial conditions. \$\endgroup\$ – Spehro Pefhany Dec 7 '17 at 7:38
  • \$\begingroup\$ looks like there is a big race condition through there when you first apply the 3.3 because of C3. \$\endgroup\$ – Trevor_G Dec 7 '17 at 7:48
  • \$\begingroup\$ The circuit is taken from this link [link]mosaic-industries.com/embedded-systems/_detail/…, and the explanation seems reasonable to me at least. I also used a pulse source and a controlled switch to simulate a push button but the cicuit is always on. \$\endgroup\$ – Marian-Emanuel Ionascu Dec 7 '17 at 8:29
  • \$\begingroup\$ did u not see c2 in that configuration is auto-on? \$\endgroup\$ – Trevor_G Dec 7 '17 at 8:51
  • \$\begingroup\$ According to the website, where other designs are analyzes, the C2 is on auto-off mode when it is tied to 3.3V. The auto-on mode that you suggest is in the link I attached were clearly the switch on C2 terminal is tied on GND. Maybe I misunderstood something. \$\endgroup\$ – Marian-Emanuel Ionascu Dec 7 '17 at 10:57

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