ir2110 problems

praondevou

Joined Jul 9, 2011
2,942
the circuit I posted is ok for 4kHz.

There is an aplication note from IR that explains how to properly size the bootstrap capacitors (the 22uF in your circuit). I think it was AN-978. Google for it.

I'm currently not at home and can't be of help for the moment.
 

gdylp2004

Joined Dec 2, 2011
101
It's necessary for the MOSFETs to get some "extra help" in turning off quickly, as an idiosyncrasy of MOSFETs is that they turn ON more quickly than they turn OFF.

This is a real problem in H-bridges, as one side (high or low) needs to be turned off before its complement turns ON, or there will be a "shoot through" condition; where the power supply is shorted out via the path through the high and low side MOSFETs.

The resistor is necessary as a "snubber" to keep the MOSFET gate from "ringing" excessively. The wire from the driver to the MOSFET gate has inductance, and the MOSFET gate acts as a small capacitor. This creates a series LC circuit that will ring like a bell struck with a hammer when the gate toggles from one state to the other.
Why is the same amount of charge (that is being charged on the gate earlier), discharge at a slower rate now? Is it because of the different path or "route" the charges have to flow away?
 

SgtWookie

Joined Jul 17, 2007
22,221
It's not that the gate discharges at a slower rate than it charges.

Look in the datasheet for any given MOSFET. It will show that the turn-on time is less than the turn-off time.

By providing a more rapid path for discharge than charging the gate, you can compensate for that difference.
 

Thread Starter

stylediva

Joined Dec 6, 2011
72
i have made that schematic..but the problem is that one of the ir2110 is getting hot..i have cross checked all the connections..but the connections are same for both the ics..kindly tell me what is the mistake????....
f=4khz , vdd=5v ,vp-p=5v ,vcc=12v ,duty cycle=50%
how can i check that ic if its working or not..shud i change the ic??...
 

Attachments

praondevou

Joined Jul 9, 2011
2,942
You use the same earth symbol on both "Vs" pins of the IR2110. Does that mean you connected them together? They are NOT supposed to be tied together. Each Vs goes to the corresponding source pin of the upper MOSFET.

Please update your schematic and also post a picture of your layout.
 

Thread Starter

stylediva

Joined Dec 6, 2011
72
here is the schematic..i connected both vs pins to the ground but one of the ic is getting hot..but now i made the connection u told..check and tell me the mistake..plz..will it work now???..
 

Attachments

Thread Starter

stylediva

Joined Dec 6, 2011
72
the same ic is getting hot..is it faulty ic??..wats the fault??..shud i chnge the ic??..i m giving the pwm signal which is attached..bt still its not working..will it work on 50% duty cycle.??..help..
 

Attachments

Thread Starter

stylediva

Joined Dec 6, 2011
72
yes i have placed the 1k resistor..and then i have checked the circuit..i m getting correct output at LO but i m not getting anything at HO..help me..motor is not moving..help..
 

SgtWookie

Joined Jul 17, 2007
22,221
Remove EVERYTHING from the side that is not working.

Test each part. You may have a shorted MOSFET. You may have a bad capacitor. You may have simply mis-wired something. You might be using wires that are too long.

After you have tested all of the parts and replaced any that are faulty, then re-build that side of the circuit, more carefully this time.

Then post a photograph of your breadboard.
 

SgtWookie

Joined Jul 17, 2007
22,221
I am glad that you have it working. And yes, praondevou has proven themself to be a most excellent advisor. :)
 
Last edited:

praondevou

Joined Jul 9, 2011
2,942
You will find the answer HERE and also HERE (from member Thatoneguy).
I couldn't describe it better.

The caps at the output part of the IR2110 (VCC/COM and VB/VS) provide the gate charge current.
 
Top