I've scratched together a design for a 555 timer based driver for an IR540 MOSFET. But in CircuitLab the simulator shows the 555's OUT voltage is always 5V when high, for Vcc ranges 3.3V through 24V. That doesn't make much sense to me.


simulate this circuit – Schematic created using CircuitLab

Does anyone know what the actual part for the 555 modeled by CircuitLab is? I've read that some 555s do have clamped output voltage, but most deliver Vcc - ~ 1.7V.

Is the modelling weird or am I just doing something dumb?

Crosslink: CircuitLab forum post

Related prior question

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    \$\begingroup\$ Sounds like a simulator bug. Did you get 5V when using a 3.3 V supply too? \$\endgroup\$ – Oskar Skog Jun 17 '19 at 3:12
  • \$\begingroup\$ yes it looks like a bug, the same thing happens when I try. As a work-around maybe use an amplifier to boost the signal to a sensible level. \$\endgroup\$ – Jasen Jun 17 '19 at 6:25
  • \$\begingroup\$ @OskarSkog Yep I tried "Vcc ranges 3.3V through 24V". So I think it's a magic part. CircuitLab doesn't simulate many ICs yet, and I guess it's rough around the edges. Amazing tool though. \$\endgroup\$ – Craig Ringer Jun 17 '19 at 7:31
  • \$\begingroup\$ Also thanks for the edig @Jasen . I couldn't get the StackExchange editor to accept an existing circuit URL when I tried, it just popped up the CircuitLabe editor for a new circuit. \$\endgroup\$ – Craig Ringer Jun 17 '19 at 7:34
  • \$\begingroup\$ cut and paste for the win. \$\endgroup\$ – Jasen Jun 17 '19 at 7:52

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