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Help on IR2104 mosfet driver

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jayzac

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Above is my design for buck converter. As i test my buck converter by supply 12V to pin 2 (IN) of IR2104 driver from dc power supply and 5v to pin 3 (SD), the mosfet is turn on. However, when i connect my buck converter to the microcontroller which supply average PWM value of 5V 50kHz 50% duty cycle to pin 2 while SD pin remain 5v, the mosfet is fail to turn off. Is there any voltage minimum value for pin 2 (IN) in order to turn on the mosfet?
 

FvM

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the mosfet is fail to turn off
or failing to turn on?
In fact, the gate driver supply voltage and boost voltage must be above the low voltage lockout threshold. 12 V should work, but not much below.
 

alexan_e

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However, when i connect my buck converter to the microcontroller which supply average PWM value of 5V 50kHz 50% duty cycle to pin 2 while SD pin remain 5v, the mosfet is fail to turn off. Is there any voltage minimum value for pin 2 (IN) in order to turn on the mosfet?

According to the datasheet with a Vcc of 10v-20v the max Vin LOW is 0.8v (anything below that will result in logic 0) and the min Vin HIGH is 3V (anything above that will be translated to logic 1).
You say that you provide 5v so this part should be fine.

Alex
 

jayzac

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Sorry for typo mistake. The MOSFET is fail to turn on. According to data sheet PWM of 5v should work to turn on the MOSFET but why it does not happens to my design. I suspect my charge pump circuit on the driver fail to produce enough charge for my mosfet. Is the 1n4148 diode and 0.1uF cap is working fine with it ?
 

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