Part Number: UCC27211
I use the UCC27211 in my project. In particular, I make the electrical circuit as in the datasheet in the half bridge configuration. In this moment, the Vhi and Vli pins are connected to ground and the Vhs pin is not connected to the transformer. I use 9V for UCC27211 and variable boot voltage from 6V to 24V for half bridge mosfet.
My problem is on Vhs pin because I always measure a constant voltage (close to the supply voltage). But if Vhi and Vli are at logical level voltage, in Vhs the voltage it should be zero. It's right?
If I disconnect the high side mosfet, the voltage on Vhs is always present.
Please, can anyone help me?
In reply to Donatello Amicone:
Sorry to hear you're still having issues. Richard will get back to you next week. Thanks for your patience!
Gate Driver Applications Engineering Manager
Dallas, TX USA
Thank you for you continued work with the UCC27211. I have some questions about the waveforms in the scope plots, to be able to give advice on making improvements.
I see the scale is 10V/div on the yellow gate signal high side waveform. Is this waveform with the scope connected to HO and ground of the converter? The driver high side output is HO with reference to HS, so looking at HO to ground includes the HS switching signal.
Can you provide waveforms with LO to ground, HO to HS with differential probe, and HS to ground? If you do not have a differential probe, then can you record the LO to ground, HO to ground and HS to ground; use the same scale and scope ground reference for HO and HS so the difference in HO to HS is clear.
It is possible the small pulses you see on HO (yellow waveform) exists on the HS to ground, and maybe not the HO-HS gate drive signal.
Also to confirm the timing, can you provide scope plots of the LI and HI signal inputs, and the HO and LO signals on the same plot?
In reply to Richard Herring:
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