1

I am trying to make BLDC driver with IR2101. MOSFETs I am using are IRFB4110PBF.

So for testing I am currently using one pair. I am using oscilloscope to see the output waveform. What I see is that it always remain high as soon as I attach power. Turns out voltage at HO stays high and at LO stays low, doesn't matter if I attach input pins or not. I come to know that IR2101 bootstrapping needs continues pwm to work so I tried giving square wave of 500 Hz on input. Vcc is 10V.

If I apply voltage on LIN, that should output 0 V, right?

Am I using the right way to check or there is something I am missing. How you check if IR2101 is working properly?

I am using below mentioned schematic. If any more info require please let me know.

enter image description here

I tried to change gate resistor to 10 ohm, main supply capacitor to 100 uF and 10 uF, added diode parallel to gate resistor for fast discharge, nothing helped.

Thank you.

winny
  • 13,064
  • 6
  • 46
  • 63
dharmikP
  • 525
  • 2
  • 11
  • 2
    How/where are you measuring? The situation you describe (HO high, LO low) cannot be maintained for very long as that would drain the bootstrap capacitor trough the 10K. So I'm doubting your measurements. – Unimportant Jul 31 '21 at 08:09
  • On the output where I mentioned "Out". Yes It should discharge but I don't see any drop over long time. – dharmikP Jul 31 '21 at 09:11
  • 9 out of 10 times it's because you wired something wrong. Double check everything...especially the things you're convinced are right. – Kyle B Jul 31 '21 at 15:25
  • 1) Replace the 1N4007 with a fast diode such as a Schottky. 2) Scope between GND and LO. Leave HIN low and put a squarewave on LIN. See if LO follows LIN. If it doesn't then the low side is not working / bootstrap can't charge and the high side can't work. If it does, connect a load such as a small lamp between VS and the power supply to check if the lower MOSFET actually conducts when LIN is high. 3) Report back by editing your question with the results. – Unimportant Jul 31 '21 at 15:53

0 Answers0