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LM5116: Gets very hot, drains 1A but works. but in no load 1A is a lot

Kamyar Keikhosravy
Prodigy 230 points
Part Number: LM5116

Hi, 

we have the following design. when we connect the input of the DCDC converter to 30V we are expecting to get 25.2V. the driver gets very hot at no load and drains 1A. the gates works.

can you please advise on why it is doing that?

our IGBTS are IPB117N20NFDATMA1. and the inductor is from WE and part number 7443556260. 

please advise 

  • 0
    TI__Mastermind 40040 points
    Can you confirm you have a VCCX supply connected to the VCCX input pin? The 1A is related to all the AC (Switching) Losses and perhaps the VCC current (if VCCX is not connected to an external supply)? Looks like your Switching frequency is set to ~1MHz (RT =3.3k), and this is the reason for your high currents. To ensure that this is the case, can you take a scope shot of the Switch node at no load?