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Can we use UC3846 for half bridge converter

Ashok Chakravarthi
Prodigy 125 points
Other Parts Discussed in Thread: UC3846, UC3525A, UCC28250, LM5035, UCC28251, LM5039

Hi,

In one of my earlier design I used UC3525A voltage mode IC for half bridge converter (with series blocking capacitor). Design is working perfectly in the field. At present I am planning to design current mode control half bridge converter. shall use UC3846 for half bridge application. 

I have seen the following article regarding voltage imbalances in half bridge converter with current mode control and it's solution. 

http://www.how2power.com/pdf_view.php?url=/newsletters/1204/articles/H2PToday1204_design_TexasInstruments.pdf

Is it necessary to implement the above solution ?; can i use series blocking capacitor in current mode control ?

  • 0
    TI__Expert 7395 points
    Ashok,

    Thanks for your interest in TI. I've contacted the relevant product group. You should hear from them soon.

    Regards,
    John
  • 0
    TI__Intellectual 1550 points

    Ashok,

    The peak current mode control would cause the voltage drift at the mid-point of the capacitive divider if the duty cycle of the two primary switches get unbalanced. This in turn causes transformer flux imbalance and eventually leads to saturation of the transformer.

    The capacitive divider is needed regardless of the control method applied.

    Typically, voltage mode control is used to control half bridge. The parts I would recommend include LM5039, LM5035 and UCC28251/UCC28250. The solution proposed in the link you provided may work but adds to the complexity.

    Regards,

    Wangxin