I'm trying to design an inverter and I'm using 2 IR2110 as gate drivers but my MCU board PWM outputs are open collector, I've added a pull-up and transistor to feed IR2110 with 5V pulses but it's not working.

Here is the full bridge and gate drive I'm using:

enter image description here

and here is the pull-up and transistor schematic I'm using between IR2110 pwm input and mcu open collector output(ULN2003A):


simulate this circuit – Schematic created using CircuitLab

Thank you for your help.

  • \$\begingroup\$ What is not working exactly? Did you measure HIN and LIN on an oscilloscoop? Moreover, do measure VB as well. I think your problem lies there: remove C1 and C5 and check whether it improves (EDIT: I removed "whether it works" since when works or does help a bit, you probably still need to put the correct (values of the) caps there.) \$\endgroup\$
    – Huisman
    Apr 12, 2019 at 9:54
  • \$\begingroup\$ @Huisman thanks for your answer, but the problem is: At the input of R2 I can detect a pulse but at the output of R2, there is no signal (2. schematic R2) so the bc337 is not working here but I don't know why \$\endgroup\$
    – Das D.
    Apr 12, 2019 at 10:09
  • \$\begingroup\$ You doublechecked the pinning of the BC337? What voltages do you measure at the input of R2? And what voltages at the base of BC337? \$\endgroup\$
    – Huisman
    Apr 12, 2019 at 10:14
  • \$\begingroup\$ @Huisman at the input of R2, There is a square pulse with 3V , but at the base I have only noise. Pins are connected true I check it many times :( \$\endgroup\$
    – Das D.
    Apr 12, 2019 at 11:32

1 Answer 1


Solved, I forgot to add pul-down resistor to base of transistor.


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