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UCC3895: How to improve light load power consumption?

Jamie Tseng
Intellectual 2405 points
Part Number: UCC3895
Other Parts Discussed in Thread: UCC2895

Hi Team,

Please kindly help on the following two questions about UCC3895:

1. When the output is unloaded, what mechanism does the IC have to reduce input wattage loss?
This IC is used on a 960W power supply. When no load is used, the input wattage exceeds 50W.

2. IC PIN 13 & 14 or PIN 17 & 18 push a Q5 Q6 MOSFET to a PULSE TRANSFORMER at the same time, how to prevent two MOSFETs from conducting at the same time?

Thanks and best regards,

Jamie

  • 0
    TI__Genius 13660 points

    Hi  Jamie, an expert will get back to you tomorrow. —— Teng

  • 0
    TI__Expert 3460 points

    Hi Jamie,

    I am pleased hear from your questions about UCC3895. I hope that the answers as below can get give your helpful.

    A1:  a,I am not sure whether you use Synchronous rectifier (SR) mosFET in secondly side. if you used SR, you can disable the SR driver at no load condition to reduce the Duty cycle to improve the efficiency in no load.

          b, it is difficult to ZVS in no load, you can increase the value of magnetic inductive in transformer primary side to reduce the switching loss.

    A2: There are 2 PIN, DELAB and DELCD, in UCC2895, which can  programs the dead time between switching of OUTA and OUTB. It can prevent two MOSFETs from conducting at the same time.

    Thanks

     

  • 0 in reply to Bliss Zhou
    TI__Expert 3460 points

    Hi Jamie,

    Since we discuss your question by email, I will close this thread.

    thanks