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BLPFC schematics

SAMEER WAGH
Expert 1040 points
Other Parts Discussed in Thread: TMDSHVBLPFCKIT

Hello,

 

I am designing BLPFC. For that i am referring TI BLPFC (TMDSHVBLPFCKIT) schematics and PFC Bridgeless [R4] Date 31-11 board.

1.In this schematics IRFB11N50A MOSFET used (please see attachment) and actually mounted MOSFET on BLPFC kit is 6R250P GA8806 for

this MOSFET i found  IPA60R250CP pdf. The specification of both MOSFET are near about same(not all) so can we substitute IRFB11N50A for 

IPA60R250CP.

2.In Vbus feedback circuit voltage divider used as shown in below attachment. In TI BLPFC user guide (Page No.25) wrote that when PFC-OUT=519 Volt then Vfb=3.3 volt Is this resistor configuration correct or not because when i measured vfb for PFC-OUT 95 volt (In build level-1 duty cycle(0.1)) is 0.620 volt.But according to voltage divider with this resistor value i am not getting correct value and also i cant found PR1 

resistor on BLPFC kit .Please correct us if there is any wrong.

Thanks in advance...

  • 0
    TI__Genius 11475 points

    1. If both MOSFETs have the same spec then you should be able to use either one.

    2. Yes, the resistor dividers are correct. Max DC bus voltage of 519V generates 3.3V at ADC input. So when the DC bus is at 95V, the ADC input will be 3.3*95/519=0.604. This is pretty close to what you got. Some mismatch because of resistor tolerance.

    PR1 resistor is not populated on the board.

    Shamim

  • 0 in reply to Shamim Choudhury
    Expert 1040 points

    Hello Shamim,

     

    I think for second question you have not gone through the attachement...

    In this R13=R14=1M and R15=22k.According to voltage divider rule

    Vfb=(R15/(R13+R14+R15))*PFC_OUT

    For PFC_OUT 519 Volt

     

    Vfb=(22k /(2M+22k))*519

       =5.6468 volt

    And our ADC range is 0 to 3.3. So how it is possible..?