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I'm building an H bridge form IRF3205 N MOSFETS to drive a TX coil for Wireless power transfer. I want to make the high side switching without a driver, instead I'm using a somewhat similar bootstrap configuration. For testing I use an active 10R load at 12 Vcc. The switching frequency is 100 KHz. enter image description here

It works, but the problem is that the rising edges for the gate of Q1 are really slow due to the R1 gate resistor. enter image description here

In the blue is VGate relative to ground and the red is signal from microcontroller. If one decreases R1, the edge rising time greatly improves, but at the expense of a lot of R1 and D1 heating because they conduct when Q5 is 'open'. What would be an efficient schematic to make a 'power efficient' gate driving circuit and since I'm not too experienced ir ringing causes, what could be the reasons for the ringing when the gate discharges?

Edit

I made this kind of gate driver. enter image description here Would it work? I would like to have not more than 300nS rising/delay times, so would need around 700mA gate charge current.

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  • \$\begingroup\$ That's the downside of open collector driving! Could you consider a MOSFET driver? \$\endgroup\$ – winny Apr 4 '18 at 14:09
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    \$\begingroup\$ What's wrong with using proper driver? ADP3120 costs 50c! \$\endgroup\$ – peufeu Apr 4 '18 at 14:12
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    \$\begingroup\$ You could harvest all your food from your back garden and cook slugs and snails with the occasional pigeon or you could go down the shop and buy some carrots, potatoes and sausages. \$\endgroup\$ – Andy aka Apr 4 '18 at 18:35

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