Queries on IR2110 driver

Hi

I wanted to know if the Vss and Com of IR2110 should be shorted. Also whether SD should be left open or connected to Vss if I dont want to use the Shut Down feature.

Thanks

I wanted to know if the Vss and Com of IR2110 should be shorted. Also whether SD should be left open or connected to Vss if I dont want to use the Shut Down feature.

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Hi Sabu
Yes Vss and come should be connected together . and about SD , it is derived from the word shut down . as i can remember if you give it a positive logical level , your driver will be off . so , you can connect it into ground via a low value resistor ( e.g 220 ohms ) however i think that IC has that resistor internally but most of the times i'm using an externally resistor to be ensure about it's behavior .
Best Wishes
Goldsmith

Yes, the VSS and COM SHOULD be shorted. You can not have them on separate grounds since the internals of the IR2110 drivermust be run off the same ground.

SD (Shutdown) pin must be grounded if it does not need to be used. When SD pin is high, the IR2110 is shut down. When SD pin is low, the IR2110 is enabled. You can directly connect SD pin to ground. You may use a resistor if you wish, but it is not required.

Hope this helps.
Tahmid.

You may use a resistor if you wish, but it is not required.

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Hi Tahmid
I think that resistor is required ! because when i didn't put it , ( when i directly connected that pin to the ground ) i saw that my driver is going to be warm ! and when i've used a low value resistor ( 220 ohms ) it worked just fine .
hence i think that's required .
Best Wishes
Goldsmith

I'm quite sure the resistor isn't required. I've used IR2110 in many many circuits, all with SD connected to ground directly. No problem!

You can go through IR's application note AN978 (www.irf.com/technical-info/appnotes/an-978.pdf) Figure 5B - Test Circuit on page 11, Figure 28A on page 25 and Figure 30 on page 27. There you'll see SD pin grounded directly (with no resistor).

Perhaps in the circuits you constructed, there was something else contributing to the heating.

Hope this helps.
Tahmid.

I'm quite sure the resistor isn't required. I've used IR2110 in many many circuits, all with SD connected to ground directly. No problem!

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But i'm not sure ! because my drivers was like this . perhaps different companies are making different drivers ? ( however my driver came from the U.S ) and if you look into the datasheet it has an internally resistor from input into ground . my drivers was like this and the problem solved with an auxiliary resistor .

Perhaps in the circuits you constructed, there was something else contributing to the heating.

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No . because when i've called to the IR technical support , they told me to test this trick . and everything became fine with this trick .

Good luck
Goldsmith

I have never had any problem directly connecting SD to ground. And according to the application note, it shouldn't be required.
Perhaps it was that particular set of drivers. Maybe.

I have never had any problem directly connecting SD to ground. And according to the application note, it shouldn't be required.
Perhaps it was that particular set of drivers. Maybe.

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Perhaps because as you probably know , components from a manufacturer are a bit different with a component from the other manufacturer .

Regards
Goldsmith

I don't see any hints in IRF documents about the said SD series resistor for IR2110. However, if it has been suggested by support guys, there's possibly some device weakness they know about. May be the pin is more sensitive to latch-up than others in specific situations. Personally I didn't experience problems without series resistors.

Regarding the original VSS and COM question: The pins should be connected to the same ground potential, but not necessarily shorted at the driver. The separate pins are provided on purpose, to allow separate power and logic grounds. The internal IC design is prepared for a certain swing of both grounds against each other. Some aspects are discussed in IRF design tip DT 97-3. If your design doesn't need separated grounds, it's O.K. to tie the pins directly of course.

To prevent a ground loop, the COM should connect directly to the Nch MOSFET's source being driven. The power supply negative should be connected with low resistance path to the output Nch MOSFET source. All driving logic's ground should branch off the Vss+COM connection on the IR2110. Don't connect the driving logic independently back to power supply.

I don't see any hints in IRF documents about the said SD series resistor for IR2110. However, if it has been suggested by support guys, there's possibly some device weakness they know about. May be the pin is more sensitive to latch-up than others in specific situations. Personally I didn't experience problems without series resistors.

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I didn't use it without resistor because most of the times i've tried to use that SD pin , as a hiccup protection ! ( all of my designs ) hence i can't tell judge about this . just i've seen that problem for some times and then i didn't tie that pin to the ground without a resistor .

Best Regards
Goldsmith

The power supply negative should be connected with low resistance path to the output Nch MOSFET source. All driving logic's ground should branch off the Vss+COM connection on the IR2110. Don't connect the driving logic independently back to power supply.

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First and third statement are O.K. For the second, it depends on what you mean with "on the IR2110". The (singular) IR2110 exists in the ideal world of example designs. In a real world, there are probably several IR2110 on a board e.g. 10 or 20 cm apart, involving voltage drops in the power circuit's DC- bus. That's where the separate logic and power ground pins of IR2110 becomes meaningful. The position for the net connector between logic and power ground can be e.g. in the middle. The wrong way would be to use power ground (DC-) as logic ground or to connect DC- and logic ground at multiple places, which would cause the said ground loops.