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UCC28516: Alternative to FAN4803CP2

Bolin Qu
Prodigy 70 points
Part Number: UCC28516
Other Parts Discussed in Thread: UCC28512, UCC28511, UCD3138, UCC28180, UCC28019A, UCC2804, UCC3802, UCC3817, UCC2818A

We are looking for alternative to FAN4803CP2. The PFC/PWM FREQUENCY are 67/134kHz. UCC28516 seems a candidate, but it is at LTB lifecycle. Please help.

  • 0
    TI__Mastermind 32050 points

    Hello Bolin, 

    Unfortunately, none of the 1:2 frequency ratio devices in the UCC2851x family are being retained for long term availability. 
    Only selected 1:1 ratio devices will remain in Active status. 

    It seems that it may be easier to redesign the existing circuit PFC for double the frequency than it would be to halve the PWM frequency.  Then UCC28512 can be used.
    If one of UCC28511, -512, or -513 is not an acceptable option, I see no recourses other than splitting control into 2 dedicated controllers for PFC and PWM, or using a UCD3138 part, which I think is excessive complication for retro fit.  

    Regards,
    Ulrich

  • 0 in reply to Ulrich Goerke
    Prodigy 70 points

    Hi Ulrich,

    Thank you for the information. We probably go with the solution of separated PFC and PWM controllers. Would UCC28180 or UCC28019A + UCC2804 be an option?

    Our circuit is very similar to Figure 12 of FAN4803 datasheet. It is a two-switch forward offline converter. The high MOSFET is driven through a pulse transformer.

    Regards,

    Bolin

  • 0 in reply to Bolin Qu
    TI__Mastermind 32050 points

    Hello Bolin, 

    Yes, UCC28180 or UCC28019A are suitable PFC options.  The UCC28019A is hard-wired for 65kHz and provide a Brown-out function.
    The UCC28180 can be programmed for 67kHz, but has no BO function. 

    In any case, the DC/DC converter will need to be synchronized to the PFC frequency in order to retain the ripple-reduction effect in the PFC output cap.  
    UCC2804 may be okay, but I am not well versed in the DC/DC controller options. 
    I suggest to post a new E2E on UCC2804 asking if this is the best option for this application retro-fit or if some newer parts might be better.

    Regards,
    Ulrich

  • 0 in reply to Ulrich Goerke
    Prodigy 70 points

    Hi Ulrich,

    Is there a way to synchronize UCC28180 PFC frequency with PWM controller? Just like UCC3817 synchronized with UCC3802 in Application Note SLUA245.

    Thanks and Regards,

    Bolin

  • 0 in reply to Bolin Qu
    TI__Mastermind 32050 points

    Hi Bolin, 

    The only way to synch the UCC28180 or -019A with a down-stream converter is to use the GATE output as signal source, and since these devices use leading-edge modulation, only the falling edge of the gate drive is a valid synchronization source.  The synching circuit may be somewhat different than shown in SLUA245 because the falling edge may have to be adapted to trigger the synch to the downstream controller. 
     
    But you raise a point I overlooked before. Using GATE as a synch-edge source depends on always having a GATE signal. 
    There can be transient moments when PWM duty cycle goes to 0 for many milliseconds or more, such as on a PFC overshoot, etc. 
    The DC/DC frequency will wander or shift until Synch is restored when the PFC PWM starts up again.   

    That may be an issue, or it may not be an issue, but the fact that it can happen should be considered. 
    Side effects of loss (and gain) of synch may include transient output deviations, EMI variations, possible OVP or OCP triggering, etc.  

    It is not possible to synch both PFC and PWM to an external clock circuit, but the UCC2818A (or similar) can avoid that.  But it is a bigger PFC part. 

    Regards,
    Ulrich