[SOLVED] Problem with HO of IR2110

[hamedo]

Hi guys

I`m trying to control 2 MOSFETs transistors with IR2110 and have a problem. On HO I have +DC 10V (without getting the MOSFETs in the circuit) and doesn`t change on any compibination of input signals. On Vb i have the same potential. I think the LO is working properly

what can i do?

 

[AKENAFAB]

Hi guys

I`m trying to control 2 MOSFETs transistors with IR2110 and have a problem. On HO I have +DC 10V (without getting the MOSFETs in the circuit) and doesn`t change on any compibination of input signals. On Vb i have the same potential. I think the LO is working properly

what can i do?

You have to connect the high side mosfet to work properly and you will see the change between states.

Regards!

 

[mtwieg]

Where are you connecting the Vs pin? If it's never brought to circuit ground, the bootstrap capacitor won't charge and the HO output won't work. For a simple test (no H bridge attached), just connect Vs to COM and GND and see if HO works then.

Also don't type like that it's annoying as hell.

 

[Tahmid]

You should post your circuit. There may be errors in it. Did you connect the MOSFETs when testing? I have never been able to test the output of the IR2110 HO on my multimeter. It always showed +12V no matter what. However, you can tell if your connection is okay by connecting the MOSFETs, connecting a load and measuring the voltage and/or observing the waveform across the load. If you are doubtful about your circuit, you should post the diagram.

Hope this helps.
Tahmid.

 

[hamedo]

thanks AKENAFAB,mtwieg & Tahmid
the problem is detected . Vs must be grounded to charge the bootstrap capacitor

but i have a question ,if this grounding will conflict with the circuit (i need to ground the floating point between the High and Low MOSFET to fire the High one in a boost inverter circuit)
What can i do ?
I already have tried to use two different supplies ,but it fails.

 

[mtwieg]

The Vs pin only needs to be brought near circuit ground periodically. This is done when the lower transistors turn on. So as long as you don't go too long without driving the low side switches, you should be fine. The amount of time the high side switches can be driven high depends on a lot of things, but as long as you don't try to drive it at 100% duty cycle it shouldn't matter.

 

[hamedo]

the average time that the low side switch turning on is 0.1 msec ,i think that time isn't sufficient to charge the bootstrap capacitor



are you know a reasonable time that i must work on ?
and what is the ratings of bootstrap and the diode related to this time ?

Regards!

 

[mtwieg]

It depends on the size of the bootstrap capacitor. But 100us should be far more than enough. Usually just a couple microseconds is sufficient, unless the capacitor is very large. You want to make sure that the cap is large enough to remain charge during the max on time of the upper switch too. Usually 10uF is plenty (so long as you're driving FETs or IGBTs).

 

[FvM]

If have used IR2110 bootstrap driver down to about 0.5 us minimal low pulse duration. You'll usually limit the duty cycle to achieve reliable operation.