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I've bought the only gate driver I've found on the local hardware store (IR21531). I want to use it only to drive a IRF630 with a PWM 3.3V signal.

How should I do the wiring? As you can see on the IR21531 datasheet, this chip seems to be intended only to automatically switch two MOSFET at a fixed frequency.

I don't care if I drive the high or the low side.


Also, if this is not possible (as @Respawned Fluff said), could I use any workaround to drive at 3.3V my MOSFET? I need to drive 200V at 5A.

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  • \$\begingroup\$ It's like asking to use your motorcycle as a bicycle. Can you take the engine off? The IR21531 is a self-oscillating driver. \$\endgroup\$ – Fizz Dec 17 '15 at 20:05
  • \$\begingroup\$ @RespawnedFluff: What would recommend me you? \$\endgroup\$ – Helio Dec 17 '15 at 20:25
  • \$\begingroup\$ "As you can see on the datasheet..." No, I can't see since you didn't bother providing a link, and I'm not going to do your job for you and chase down the datasheet. Also, the right FET driver is available at the other end of the internet. \$\endgroup\$ – Olin Lathrop Dec 17 '15 at 20:38
  • \$\begingroup\$ @OlinLathrop: Sorry, I forgot to add link. \$\endgroup\$ – Helio Dec 17 '15 at 20:39
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    \$\begingroup\$ @OlinLathrop: Can you elaborate on the meaning "The other end of the internet"? \$\endgroup\$ – Helio Dec 17 '15 at 20:41
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You won't be able to use the IR21531 the way you desired. This device does not accept an input signal (other than Shutdown) where you can directly control the gating rate and duration of gate pulse.

You said you want to use a 3.3v PWM signal to drive your FET (MOSFET). Search on the internet or in stores for a Low Side Driver. Even here on EE Stack Exchange there are many answers when searching for drivers and low side drivers.

Exixsting questions that may help you:


Another solution would be to use a gate driver like MIC5019 that includes internal charge pump to convert 3.3V into 10V.

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    \$\begingroup\$ Technically it doesn't even have shutdown; you do that by shorting the cap [pin] to gnd. I suppose the way this driver is normally used is with a pot instead of that resistor (between RT and CT), so you can adjust the duty cycle that way. Perhaps using a digital pot instead would work, but would be a rather pointless complication. Also, the digital pot would need to be PWM driven/adjusted, which is not how most of them work. \$\endgroup\$ – Fizz Dec 17 '15 at 20:47
  • \$\begingroup\$ Thank you very much for your diligent response! The first example draws unuseful for me, beacuse 2N3906 has 40V as maximum voltage. Now I'm reviewing the second one. \$\endgroup\$ – Helio Dec 17 '15 at 20:54
  • \$\begingroup\$ @RespawnedFluff: I really appreciate your comment, and after reading it, I see clearly that is better to find another gate driver, as using it will end in a bigger, expensive and ineficient implementation of my idea. \$\endgroup\$ – Helio Dec 17 '15 at 20:56
  • \$\begingroup\$ Second example using TC4421A. The driver doesn't have to withstand your 200 volts. However the lowest voltage the TC4421A can operate from is 4.5 volts (4.5v to 20v) \$\endgroup\$ – Marla Dec 17 '15 at 20:57
  • \$\begingroup\$ I'm doing a very compact design where I only have a 200V power supply and a 3.3V power supply. Where could I get 20V? \$\endgroup\$ – Helio Dec 17 '15 at 21:02

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