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I have got a PWM board from china that outputs at 5V but at 100 kHz, the voltage drops to about 2.82V. Hence I have implemented a mosfet driver to pull the amplitude ideally to be 10V to drive a mosfet that is part of a SMPS.

The mosfet driver that I was using was Microchip TC427CPA. I used a PSU of 12V while experimenting and the result was only about 5.5V output DC.

I tried adjusting the PSU to 17.5V and I've got an output of 8.28V DC. Based on the data sheet, it mentioned that output voltage should be Vdd - 0.025. I've grounded the other input interface and I've connected decoupling capacitance between Vdd and ground as per the datasheet.

Any advice to achieve the desired output?

I tried using Microchip TC4432EPA and while the PSU was set at 12V, I was able pull the output to 10.93V measured at pin 7 (Source Output). However I'm a bit confused with Pin 6 (Sink Output) and Pin 7 (Source Output) for which pin will be suitable to drive the N Channel Mosfet of my SMPS.

I am also unsure if the Microchip TC4432EPA is suited for SMPS applications as well. I hope someone can guide me along. Thanks in advance!

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  • \$\begingroup\$ How are you measuring the voltage? \$\endgroup\$
    – HandyHowie
    Oct 6, 2017 at 10:48
  • \$\begingroup\$ @Handyhowie as my oscilloscope is down at the moment, I’m using a voltmeter to measure at the output \$\endgroup\$
    – Iskandar
    Oct 6, 2017 at 11:07
  • \$\begingroup\$ Are you checking the voltage with the PWM running? If so, what is the duty cycle when testing the voltage? \$\endgroup\$
    – HandyHowie
    Oct 6, 2017 at 12:06
  • \$\begingroup\$ @HandyHowie yes Im running the PWM with 50% duty cycle. \$\endgroup\$
    – Iskandar
    Oct 6, 2017 at 12:24
  • \$\begingroup\$ In that case your voltmeter will probably show an average voltage which will probably be 50% of what you are expecting. You really need to use an oscilloscope to see the 'on' voltage. \$\endgroup\$
    – HandyHowie
    Oct 6, 2017 at 12:43

1 Answer 1

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Since you are running the PWM at 50%, it looks like your voltmeter is showing an average voltage which will be 50% of the 'on' voltage. Use an oscilloscope to get the true 'on' voltage.

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  • \$\begingroup\$ I will try get access to an oscilloscope. Any idea if the other mosfet driver is able to drive SMPS as well? \$\endgroup\$
    – Iskandar
    Oct 6, 2017 at 12:52

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