Need help with mc33260p

[mjunaid61]

Hello guyz , I am doing a project of power factor correction using mc33260p . I am implementing the follower boost topology . I am facing real trouble with running this IC and there is no test cuircuit or debugging information available on the internet. I need Guidance for running this IC , Plz can anyone hel;p me........I also want to know that if i want to operate it on 15V rms using function generator than how will this effect output voltage and other design elements???

 

[moffy]

Have you looked at: MC33260P Datasheet pdf - GreenLine™ Compact Power Factor Controller: Innovative Circuit for Cost Effective Solutions - ON Semiconductor and the application note (the first item) AND8123D?

 

[mjunaid61]

I have tested the circuit given in AND8016. I placed each and every component of exact value given in that document but as a result my MOSFET and the controller both were damaged, The pin 7 and ground were shorted due to some unknown reason.
Can anyone help me with my project as it is of 9 credit hours.

 

[moffy]

Though it provides a complex function, it only has 8 pins and requires a handfull of components to operate. You could run it off 15v RMS as long as you scale the FB resistor(pin 1) and the input/inductor current sense resistor appropriately. At such low voltages the inductor will be easier to spec.

The mosfet failing and pin7 going short sounds suspiciously like an overvoltage event killed the MOSFET then destroyed the IC. You need excellent voltage clamping at the drain of the MOSFET (a snubber is good, as well as very high speed diode and high speed cap, to stop the ringing). Also you need to heavily overated the max voltage of the MOSFET, I'm usually comfortable with doubling it.e.g. for 200v max use a 400v MOSFET. They do not like overvoltages!

 

[mjunaid61]

thanks moffy , one more question

at 15 v rms what will be the output voltage?? does it depends upon Ro which is given by V0/200u?????????????

 

[moffy]

Yeah. Vo = 190u*Ro + Vpin1(about 2.6v). Of course it will have to be a bit lower than peak voltage. It will also vary a little as the regulation has a little slack, but not much.

 

[mjunaid61]

@moffy
Thanks for your help. I am going to implement the circuit using function generator tonight. I will tell you the results tommorow

 

[mjunaid61]

Hi there . well it hasn't worked. Dont know what to do

 

[mjunaid61]

Well it has worked with 15V rms input Thanks

 

[moffy]

Glad to hear it! My previous post about the voltage for the MC33260P was a bit nonsensical. Didn't really have a handle on how the chip works. It seems to me, that the inductor and storage cap play a fundamental part in loop stability. It would also be important to ensure that the inductor doesn't saturate(guess that's what the current limit is for). Still it's wierd the way it works, for so few components it sure is complex.