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drive circuits for IRF840

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missk

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hi

I have tried to drive an IRF840 mosfet using the IR2111 driver.I have read the datasheet, previous threads, application notes, googled etc...beggining to think my idea was not for me as I absolutely cannot get any sort of response from the IR2111.


Im getting a 5V PWM signal out from a MCU that needs to drive the mosfet on. I know I need about 12V to fully turn the mosfet on, I would appreciate any alternate driver circuit suggestions.

thanks
 

If the MOSFET has it's source connected to ground, a low side driver IC like TC426 - TC429, or another 5 to 12 V level converter would work. But the low-side driver part of the IR2111 should work as well.
 

post a schematic so that we can understand what you are doing and the connections and voltages involved

Alex
 

Hi again, thanks for the suggestions. I have attached a schematic.
 

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    CIRCUIT.png
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I should have mentioned that my mosfet is used in a dc-dc converter, with a switching freq of 30kHZ. my MCU outputs a duty cycle to the mosfet driver, which is supposed to be driving the mosfet high... please let me know what else is needed.
 

Your circuit can only work, if the node labelled "-25V" is connected to GND. And remove the short from LO to GND. There's no bootstrap operation, so Vb could be directly connected to +12V without a diode.
 

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