Gate Driving of IR2113

[Erik. Ng]

Hi,

May I know what is the purpose of the bootstrapping circuit in IR2113 typical configuration?
And why does the Lo does not requires the bootstrapping?

 

[audioguru]

Most N-channel Mosfets need their gate voltage to be +10V higher than their source voltage.
BOTH Mosfets used with a IR2113 are N-channel.
The bottom Mosfet is a common source circuit so its source pin is at zero volts and when its gate is at +10V it turns on.
But the top Mosfet is a source follower and for its source to be as high as it can go near the supply voltage then its gate voltage must be +10V higher than the supply voltage.
Bootstrapping is used to doo eet.

 

[Erik. Ng]

What do you mean by doo eet? What's the difference between direct switching and switching through IR2113?

 

[audioguru]

What do you mean by doo eet?

DOO EET is "do it".

What's the difference between direct switching and switching through IR2113?

The IR2113 provides bootstrapping for the upper N-channel Mosfet and a much higher supply voltage can be used for it if you want. Without bootstrapping then the upper Mosfet might not ever turn on if the supply voltage is low or if the supply voltage is high it will not turn on enough. You could make the complicated circuit yourself that is already inside an IR2113 IC.