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I have bought 4 N-Channel MOSFETs to build an H-Bridge Motor Driver. My Motor drive and my power supply voltage is 12v. My TTL logic voltage is 5v as I want to speed up/down the motor with uC PWM. Now I have understood that I have problem with driving High Side MOSFETs as their Gate Voltage must be bigger in respect to their Source voltage. What are my options now? shall I change them to P-Channel MOSFETs?

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  • \$\begingroup\$ It would certainly simplify your circuit if you used P MOSFETs - you only need to replace two of them. \$\endgroup\$ – JIm Dearden Aug 22 '13 at 19:43
  • \$\begingroup\$ @JImDearden Will I be limited to a lower current if I use P MOSFET? as I need 5A current for my Motor \$\endgroup\$ – Mehrdad Kamelzadeh Aug 22 '13 at 19:48
  • \$\begingroup\$ no - just make sure you get one that is complimentary to the N type. It will switch as much current. \$\endgroup\$ – JIm Dearden Aug 22 '13 at 19:51
  • \$\begingroup\$ How can I figure it out that it is complimentary to mine or not? Mine are P5N60 \$\endgroup\$ – Mehrdad Kamelzadeh Aug 22 '13 at 19:54
  • \$\begingroup\$ look up the data sheet - the P5N60 is a 5A, 600V N MOSFET so your looking for a P MOSFET 5A, -600V. You may also want to match the DRAIN-SOURCE resistance. As you don't need 600V you could safely choose a lower voltage type - say 30V. \$\endgroup\$ – JIm Dearden Aug 22 '13 at 20:08
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Check out this device.

http://www.linear.com/product/LT1910

It's a high side N-channel MOSFET driver. I think that it has a little boost converter internally. We've just started playing with these and it will drive the MOSFET gate to 20 VDC with a 12 VDC supply. Nifty huh?!?

Though the device isn't fast, relatively speaking, so you would be better off doing PWM for speed control on the low side MOSFET. You can get a regular FET driver to do this with your 5 V input.

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For half bridge just use one of these: -

enter image description here

For full bridge use two. These devices are able to drive n channels topside because they smuggle a bit of energy away from the output using a capacitor \$C_{BOOST}\$. The 1N4148 is for startup I believe.

There are other devices that can do this too.

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This is entirely possible but you need some way to generate the higher-than-supply gate voltage required by the high-side MOSFET. There are several possible ways of doing this:

  1. Generate this high side voltage from a separate source, using something like a sub-US$0.1 chip like MC34063 connected into a small boost converter. This method works with any drive waveform

  2. Use a gate driver chip like the sub-$1 IR2110. This requires a PWM drive waveform as it generates this high voltage using a bootstrap process (essentially a switched capacitor synchronous charge pump)

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You should Use IR2101, Its a half bridge gate driver IC with all the details mentioned inits datasheet. Its very useful.try it.

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