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UCC28704: Flyback converter with PSR (Primary Side Regulation)

said DAYF
Prodigy 10 points
Part Number: UCC28704
Other Parts Discussed in Thread: UCC28C45

Hi,

I'm working on a development of a specific power supply (I have chosen a Flyback topology) my specifications are as follows 

 1. Four Output Isolated

 1. Input Voltage :   10VDC-400VDC

 2. Output Voltage:   20VDC in each output 

 3. Output Current : 0.016A in each output 

 4. Response time of my power supply should be shorter than possible (less than 600us)

Can I use the UCC28704 with primary side regulation for that ?  It is possible to eliminate the soft start of the UCC28704 in order to start-up faster as I can ?

Pls do the needful. 

Best Regards,

D.SAID

  • 0
    TI__Expert 8210 points

    D.SAID

    Unfortunately UCC28704 will not work for this requirement.  The abs max UVLO turn on threshold on VDD for UCC28704 is 23V, so UCC28704 cannot guarantee to startup with any voltage below 23V.

    We recommend you consider UCC28C45 for your application instead.  It has a UVLO threshold that is low enough to allow support for a 10V-400V DC input, it does not have soft start (soft start can be added externally following section 8.3.7/page 18 of the datasheet) and it can support primary side regulation if you connect the feedback circuit to the auxiliary winding.

    Best Regards,

    Eric