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Gate Driver ICs Forum Discussions

User16284
Level 1
Level 1
Hi

I am working on a synchronized buck converter using the integrated IR2110 as driver for the mosfet, I see that when the output capacitor (C1) is connected dead time on the HO pin there is 12V, but I have not yet identified the reason for because this happens

Attached is a capture of the simplified circuit diagram, and the signals taken at different points:

Yellow: IR2110 HIN
Blue: IR2110 LIN
Violet: IR2110 HO (marked in orange dead time)
Green: IR2110 VS

Duty cylce: 50%
Dead time: 2 uS


Can you help me identify the reason?
Thanks


3373.attach

3370.attach
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1 Solution
wchu1
Employee
First solution authored First reply posted First question asked
Employee
Hi Jsaalva:

I guess this is because there isn't enough energy which stored in the buck inductor (when the high side Mosfet is on) to charge the output capacitor (when the high side Mosfet is off).

That means the buck converter works in discontinuous mode. You may use the current probe to check the inductor current to see the difference between with and without the output capacitor.

Regards
Weidong Chu

View solution in original post

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3 Replies
wchu1
Employee
First solution authored First reply posted First question asked
Employee
Hi Jsaalva:
The operation of the driver looks fine.
Please use the differential mode voltage probe to check the waveform between HO and VS. The reference of high side Mosfet (Q1) is VS, not COM.

Regards
Weidong Chu
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User16284
Level 1
Level 1
Hi Weidong Chu,

I agree with what you are saying, with respect to VS are zero volts (which is correct), however, my doubt is that without the output capacitor (C1), the HO voltage during dead time is zero volts with respect to COM (not vs), but with C1 is 12V respect COM, that's my doubt


Thanks
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wchu1
Employee
First solution authored First reply posted First question asked
Employee
Hi Jsaalva:

I guess this is because there isn't enough energy which stored in the buck inductor (when the high side Mosfet is on) to charge the output capacitor (when the high side Mosfet is off).

That means the buck converter works in discontinuous mode. You may use the current probe to check the inductor current to see the difference between with and without the output capacitor.

Regards
Weidong Chu
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