Is there something missing in gate driver(IR2117) circuit of a buck converter? help.!

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AbhimanyuSingh

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This gate driver is for a buck converter. The input to this IC is a nice pulse of frequency 100 KHz of variable duty ratio. I have checked the circuit many times and ensured that no shorting is there. But the output remains 0 volts. The output HO is hanging as well as the output VO is hanging. For the sake of step by step progress, I have left them hanging. Is there something I have missed or something I dont know that I should have done.
 

I don't know an output VO of IR2117.

Generally, the output will not turn on, if either VCC-COM or VB-VS is below the undervoltage lockout threshold of about 9.5V. You should be able to check this condition.

You possibly need to limit the buck converter duty cycle below 100% to allow correct operation of the driver. A non-synchronous-switching buck converter may need a means to pull down the switching node and charge the bootstrap circuit at startup.
 

Its pin VS and not VO.
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O.K. But VS isn't an output. It's the ground for the floating high side supply, driven by the power switch. HO is the signal of interest.
 

Okay, firstly, you won't be able to check the output of HO with Vs floating because, it's floating. Connect VS to gnd momentarily just for checking purposes, and you can see the signal at HO with respect to gnd.
Then if all is okay, disconnect Vs from gnd and connect it to your circuit. You won't be able to check pulses at HO with reference to Vs as that's floating.

Hope this helps.
Tahmid.
 

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