IR2110 Half-Bridge Circuit design

Hello ,

I want to design a Half-bridge circuit with IR2110 to drive an 60W ultrasonic transducer which operates at 35-40khz and 600V. first I generate PWm signal via PIC IC's CCP module on half bridge mode. Then I amplify this signal to 12V. IR2110 operates 12V too.. Here is my schematic:

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My n mosfets (10A, 600V), when I test my circuit without a load on Vs-gnd. I see 0-12 Vpp square signal. When I look HO and LO one by one. HO seems 12V PWM signal but on LO pin signal amplitude is so low. and when I change pwm freqeuncy, the output signal doesnt change... So my circuit is not working right?, where is my problem I spent lots of time with hoping to increase my 12V PWM signal to 600V amplitude... Plz help me on this problem, I am nearly exhausted... My n mosfet are burning after 8-10 minutes:roll:

ultrasonic said:

My n mosfets (10A, 600V), when I test my circuit without a load on Vs-gnd.

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You'll have to clarify this. Do you mean there's no load on the half bridge, or no load on the HO/LO outputs? What do you mean by "without a load on Vs-gnd?"

A good way to start testing the driver is to connect VS to ground (COM) and completely detach the mosfets and H bridges from the circuit. Now you have both HO and LO outputs ground referenced. Check that you get correct PWM signals from both of them.

mtwieg said:

You'll have to clarify this. Do you mean there's no load on the half bridge, or no load on the HO/LO outputs? What do you mean by "without a load on Vs-gnd?"

A good way to start testing the driver is to connect VS to ground (COM) and completely detach the mosfets and H bridges from the circuit. Now you have both HO and LO outputs ground referenced. Check that you get correct PWM signals from both of them.

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Yes I mean that there is no transducer connection on the output of the Half bridge. I have tested IR2110 as you said before, and I can see that it works properly. But when I build half bridge with n mosfet at the end of HO and LO without adding any load to the output of half bridge circuit I mean after the mosfets, the signal looks like 12 Vpp a square wave and it doesnt change when I change duty cycly and frequency...

What is the phase of the output waveform with respect to the Hin and Lin and Ho and Lo signals? Give a picture if possible.

mtwieg said:

What is the phase of the output waveform with respect to the Hin and Lin and Ho and Lo signals? Give a picture if possible.

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when I connect Vs to COM, and HI and HO status like that:

1-) HI input signal

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2-) HO output signal

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Can't see the phase relationship when the traces are acquired independently. Are they on different timescales too?

mtwieg said:

Can't see the phase relationship when the traces are acquired independently. Are they on different timescales too?

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Yes the phase is different for two signal. But when I didnt connect LI signal they have the same phase actually.

You say "different" but that doesn't really help. If those two images are on the same time base, then it looks like the output is giving two pulses for every input pulse... but it's impossible to tell unless you show the two waveforms simultaneously.

mtwieg said:

You say "different" but that doesn't really help. If those two images are on the same time base, then it looks like the output is giving two pulses for every input pulse... but it's impossible to tell unless you show the two waveforms simultaneously.

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hi mtwieg,

here is the HO,LO output with respect to H-bridge output:

1-) HO and H-bridge output:

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2-) LO and H-bridge output:

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For first image, how can I reduce noise on high state of PWM? For second image, LO is so small than H-bridge output? I am not sure that my circuit is giving correct result? For the first time I am using this IR2110 and half brigde