L4984D CCM PFC Controller

[Trotila]

Hello guys

  I am working on a switch mode power supply with PFC  and for the latter I have picked L4984D IC. 

 The reference circuit design I obtained with the help of eDesignSuite online tool.

   

Upon assembly of the circuit, as a safety measure , I powered it through a series bulb and straight away, things did not look promising. there were no shorts, but the voltage at the INV pin measured at 0.7v , which according to the datasheet ,told me that there was a feedback failure. After inspecting all the feedback resistors and double checking the circuit, I discovered that VCC voltage was dropping below VCCON. rectified it and then Series Bulb light up brighter than before and had a pulsating visuals( not completely dimming). did more checking and found out that the main bulk voltage was dropping to 110V , which is far too low and now the only suspect seemed to be the series bulb. before bypassing it, I did one final measurements to make sure it was safe to directly turn the circuit and then I proceeded to giving it the line voltage. as a result I got the IC blown, as well as the current sense resistor and switching MOSFETs . the trace to the MULT pin got completely evaporated. have been scratching my head, what could have gone wrong. The eDesignSuite suggested  STP65N045M9 MOSFETs , I could not source them and picked replacements as close to them as possible, GBS65060TOB MOSFETs. i have attached both eDesignSuite picture as well as my replicated circuit.

Please take a look if you may. Maybe i have made an error, maybe you will advise me on some thing. i would greatly appreciate it.

Thank you in advance

Saba

[Peter BENSCH]

Welcome ​@Trotila, to the community!

Well, you have given no information about the topology, the wiring, or the layout. You have also designed the circuit with an ST MOSFET and simply replaced it with one from Gosemicon with completely different data, for example R_G and Q_g. For a 3kW design with estimated peak currents of around 40A at 180V, you should proceed much more carefully and, if necessary, look for a local partner who has experience with such power levels and the necessary test equipment.

Because of the high power, I would also consider a multiphase design instead of your single-phase design in order to minimise the ripple on the input side.

By the way, I briefly simulated your design with eDesignSuite as a test, and the boost inductor had to have significantly more inductance at 200µH than the 100µH in your schematic. Speaking of the inductor: what saturation current does yours have?

Regards
/Peter

[Trotila]

Hello Peter

 Thank you for responding. my apologies for a delayed answer

   I will try to provide as much information as possible.

   It is a phase shifted full bridge topology. As an auxiliary power , I use TOP270EG from Power Integrations.

 For the phase shifted controller I use UCC28950PWR from Texas Instruments. For gate drive I use UCC27324DR.  Being this a prototype , I decided to divide the circuit into sections and power them one after the other  to narrow down any possible faults on the road. So far I have turned on only auxiliary power and PFC section, phase shifted section is not on currently. About the different MOSFETs , I agree, it was a risky approach, I simply could not source the suggested ones. 

PFC inductor I have picked based on eDesignSuite calculations. I have no idea why I got different value compared to yours. 

The saturation current of the inductor is 35A.

sorry for somewhat messy circuit diagram, I had to make PFC and phase shift control boards a plug-in type, hence why net labels spiraled out of control .

Regards

Saba