I have following diagram on falstad

enter image description here

Top +5V is main PSU (12V 10A). Bottom +5V is battery (12V 2.3Ah). I have load about 2-3A so I dont think diode is good solution. Well I am trying to achieve following: While PSU is plugged then run circuit from PSU and charge battery. When it comes to power outage I would like to run circuit from battery.

What is not working? I dont know if its falstad issue or not but while PSU is active there is no current flowing to battery via resistor. Also I forgot to mention if there is power outage on PSU I definitely not want to charge PSU from battery (thats why there is mosfet) because behind mosfet will be 2 resistors to measure voltage by IC to notify user there is power outage.

  • \$\begingroup\$ It’s your design. Pch is reverse biased on Vgs . You can edit Vdd,Vss and also gm or Beta of each device and Vt of each device with a “slider” or fixed value on Falstad. always assume your model is wrong in Falstad before blaming the physics in Falstad with known limitations on LED parameters which you can also change a model of a battery as 10kF + Vmin voltage source + ESR and reduce time sample to seconds vs us \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 28 at 13:08
  • \$\begingroup\$ @SunnyskyguyEE75 ok. What should I do to fix it? Im bit new to mosfets \$\endgroup\$ – user1085907 Jun 28 at 13:15
  • \$\begingroup\$ buy or use the IC model for the DW-01A. Your lower PFet is not ON since it is pulled high \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 28 at 13:52
  • \$\begingroup\$ @SunnyskyguyEE75 Its okay that PFet is off. It should be by design if NFet is ON. I just dont know why current is not flowing via resistor to another +5V (bottom - battery) to charge it \$\endgroup\$ – user1085907 Jun 28 at 13:57
  • \$\begingroup\$ The switch on high side does not pull Pch gate to 0V when it Opens or PS is unplugged so add R gate to 0V \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jun 28 at 13:59

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