LC circuit

Jessica Shaw · 2011-11-12T02:32:13+00:00

Hi,I want to drive a LC circuit using full H bridge at the rate of100KHz. I am expecting to get the 400 Volts peak to peak voltageacross the load. This voltage will appear at the source terminals ofthe NMOSFETS ( upper High Side).I used HIP 4081A with four NMOSFETS to do this but the transistors gethot after sometimes. I would appreciate if someone has used this chipbefore and can advice. I operated the HIP chip in bistate timing mode.The HIP chips keeps the high side MOSFETS on and only turns OFF and ONthe lower side MOSFETS. But the thing is that the 400 volts appear atthe source terminals of the MOSFETS and effects the AHS and BHS inputsof the HIP chip. So, I reomved the connection between the AHS and BHSpins from their corresponding NMOS transistors's sources and tied theAHS and BHS pins with +12 volts. But doing so is shorting my 12 voltspower supply and current increased from 0.3 A to 2 A.. which I do notknow why?Schematic:I am also thinking of getting rid of the HIP chip all together anddesign my own driver. I have looked on the internet and found someliterature. One of the application notes say that the upper sideMOSFETS should be PMOSFETS and the lower side should have NMOSFETS.And it also suggests npn transistors to drive these MOSFETS. But Ihave no clue how to choose the parts and what direction should I taketo design the driver. Any advice will be appreciated.thanksjess

Nov 12, 2011 25 Replies

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Jessica Shaw 14 years ago

Hi,

I guess that the load is both parallel and series.

jess

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John S 14 years ago

What is the power supply current with the oscilloscope disconnected from your circuit?

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Jessica Shaw 14 years ago

Hi,

When HIP 4081A is working fine than 2.3 A with or with out scope.

jess

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John S 14 years ago

What are the values of the load components?

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John S 14 years ago

Then where do you get 1.6 A?

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Jessica Shaw 14 years ago

I changed the transistors and also driving two sets of loads with two bridges. So, the current draw is 2.3 A when driving two bridges. .6 when just driving one brigde. jess

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