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UCC28730-Q1: Input voltage range

user5795788
Prodigy 30 points
Part Number: UCC28730-Q1
Other Parts Discussed in Thread: PMP10200, UCC28700

According SLUA987B description,The UCC28730-Q1 can design Automotive 40V to 1kV input flyback converter,but Ivsl(run)=220uA,Ivs(max)=-1.2mA,The input voltage range maximum 1.2/0.22=5.5 times,Unable to do input voltage range 40V to 1KV flyback converter. 

  • 0
    TI__Expert 8210 points

    Hi

    UCC28730-Q1, along with the rest of the UCC287xx PSR/SSR flyback family, can support an input voltage range wider than 5.5x.  An example of this is with UCC28700 (which has the same control law as UCC28730-Q1) in PMP10200.  The input voltage range of this design is 25VDC and 520VDC, which is 20.8x. 

    Please note that for such a wide input voltage range, the controller is unable to supply max power at lower input voltages due to the limits of the control law.  You can get around this by setting the maximum power at higher input voltage higher.

    Best Regards,

    Eric

  • 0 in reply to Eric Faraci
    Prodigy 30 points

    During the MOSFET on-time,The VS pin current generated through Rs1 by reflected Vin voltage(Npa=Np/Na,reflected voltage=Vin/Npa),The Ivsl(run)_max=275uA;assume:Vin(min)=50V,Npa=5,Vin(max)=600V,To ensure flyback converter normal operation of Vin(min),The Rs1(max)=Vin(min)/(Ivsl(run)*Npa)=36K,in the case of Vin(max),Ivs(max)=Vin(max)/(Rs1(max)*Npa)=3.3mA,The VS pin current is greater than the limit value(≤-1.2mA).

  • 0 in reply to user5795788
    TI__Expert 8210 points

    Hi

    As I previously shared, PMP10200 is an example design with that demonstrates support for output voltage from 25VDC and 520VDC, which is 20.8x.  This reference design is highlighted in the related documentation section of the app note you referenced https://www.ti.com/lit/an/slua987b/slua987b.pdf.

    We recommend that you use our excel design calculator http://www.ti.com/lit/zip/sluc579 

    Best Regards, 
    Eric