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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
 

FvM

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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.
 

alexan_e

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

Alex
 

missk

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

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missk

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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.
 

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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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