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enter image description here

My intent is to make sure that when the top mosfet is on the bottom mosfet is off and vice versa. I'm really not sure that this accomplishes the goal. Is there some better way than this? I'm using two current sources that are configured to one second intervals. My sim doesn't look quite right when I turn it on both 1V batteries are pumping current through the mosfets.

I tried the PWM it was a little too complex for me right now but I did come up with something I though maybe works too: enter image description here

So this must be what the PWM diagram is kind of saying: enter image description here

Thank you

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    \$\begingroup\$ Why are you using two sources? Why not just tie the inverter to the output of the top source and get rid of the bottom one? \$\endgroup\$ – tcrosley Jan 22 '15 at 7:20
  • \$\begingroup\$ I also suspect that connecting the other source pin to ground might be a killer. \$\endgroup\$ – Vladimir Cravero Jan 22 '15 at 8:14
  • \$\begingroup\$ Now that you added more images I am sure that your problem comes from not connecting the square generator to ground. Please do it and profit. \$\endgroup\$ – Vladimir Cravero Jan 22 '15 at 9:39
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Using an inverter is not going to work. You need to use shoot-through protection: -

enter image description here

The OR gate output needs to be inverted so an alternative is to use a NOR gate. It's going to work best when both AND and NOR/OR are schmitt trigger input types. For a quick simulation make the resistor 1k and the capacitor 10nF - this will give a "dead" area of about CR or 10us but clearly the time of the dead area is dependent on the application.

enter image description here

See also this stack exchange page.

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  • \$\begingroup\$ Would he need shoot-through protection here since they are not configured in a bridge (high side/low side)? I don't see a path to ground through both FETs, so why the dead-time requirement? \$\endgroup\$ – RYS Jan 22 '15 at 8:38
  • \$\begingroup\$ I'm trying to put that in my simulator. Could you identify the gates. I'm guessing a bit about what they are. I see a capacitor. What is the box symbol? \$\endgroup\$ – Eae Jan 22 '15 at 8:53
  • \$\begingroup\$ An OR gate, an AND gate and a resistor. Use Schmitt trigger versions of the gates. It works because I've used it. \$\endgroup\$ – Andy aka Jan 22 '15 at 9:38
  • \$\begingroup\$ @RYS it's the same requirement as shoot thru protection - read what the OP says in his question. \$\endgroup\$ – Andy aka Jan 22 '15 at 9:49
  • \$\begingroup\$ I tired to get as close as I could to that you posted. It's there as an edit. \$\endgroup\$ – Eae Jan 22 '15 at 10:07
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One way could be to build your own CMOS using a PMOS and an NMOS. Look up CMOS logic or something like that to get the gist.

If you wanna do it your way, i'd hook the gates up to the same current source - one with the inverter, one without. Please note that I'm not at all familiar with the simulation environment you're using.

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  • \$\begingroup\$ It's a program called Every Circuit for the Android. \$\endgroup\$ – Eae Jan 22 '15 at 8:32

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