I'm trying to design a buck converter (not synchronous). I use IR2110 (high side) to control the mosfet. As I know that pin VS need to connect to GND so the bootstrap capacitor can be charged. But by that way, accidentaly, in buck conveter, 2 side of the diode are short-circuit.
If I use another source for IR2110 and separate 2 GND then It's not able to send the PWM to HIN pin.
I'm confused about that. Could anyone please help me!

 

I'm trying to design a buck converter (not synchronous). I use IR2110 (high side) to control the mosfet. As I know that pin VS need to connect to GND so the bootstrap capacitor can be charged. But by that way, accidentaly, in buck conveter, 2 side of the diode are short-circuit.
If I use another source for IR2110 and separate 2 GND then It's not able to send the PWM to HIN pin.
I'm confused about that. Could anyone please help me!

I think, Pin VS connects to the Source of the MOSFET, not to GDN.

Connect the IR2110 to the MOSFET like this ...
https://i2.wp.com/microcontrollersl...C16F877A-microcontroller-and-IR2112.jpg?ssl=1

 

I think the circuit in that link is not gonna work, because if pin VS doesn't connect to GND so the bootstrap capacitor can't be charged.
The pin VS should connect to the both source of mosfet and GND

 

The pin VS should connect to the both source of mosfet and GND

With Vs going to ground, the source output of the MOSFET is grounded, so obviously there's no output.

Vs goes only to the MOSFET source, not to ground.
The bootstrap cap then charges during the time the MOSFET is off and the source voltage goes to near ground potential because of the freewheeling diode D2.

 

VS does go to ground in a normal use of a half bridge driver, when the low side mosfet gets turned on. When not using the low side there has to be a "gate charge pump". Here is a driver that has one built into it - https://www.analog.com/en/products/ltc1155.html

There is with a Google search other available - https://www.google.com/search?clien...gws-wiz.......0i71j0i22i30j33i299.TJzQul83yYI

 

Thank you guys. So it is impossible to use IR2110 with only high side to control the mosfet in buck converter. Am I correct?
I actually don't really understand how the bootstrap capacitor is charged and discharged.

 

So it is impossible to use IR2110 with only high side to control the mosfet in buck converter. Am I correct?

Not correct. Just connect the Vs pin to the source of the FET. See post #4.
Remove C2.

 

But due to the diode, the bootstrap circuit is not closed so the cap can't be charged. ??

 

But due to the diode, the bootstrap circuit is not closed so the cap can't be charged. ??

See diagram below.

When the MOSFET turns off, the inductor current continues to flow, but now through the diode, which pulls the source (and bootstrap capacitor) to one diode drop below ground.
There is thus a low impedance path to ground (potential) for the cap at that point (a forward biased diode has a low impedance).
The bootstrap capacitor then charges to the supply voltage through the top diode.
It is thus charged so it can be applied between the gate and source to turn the MOSFET back on for the next pulse.

Make sense?

 

I didn't know that the capacitor can be charged like that way before.
I understand. Thank you for help!