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UC3525A: Low Cost High Current Buck Converter

Mike Miles52
Prodigy 50 points
Part Number: UC3525A
Other Parts Discussed in Thread: MC34063A, , LM5119, PMP10979, LM25119

Hello, I need to design a buck converter that will limit the voltage in an automotive-type dc system. The input may be from 11 to 15 volts; the output should be regulated to a maximum set point (e.g. 13 volts). So if the input is higher, the output stays at that set point; if the input is lower, it would simply follow the input voltage (as closely as possible). Output should be about 60 amps. But it needs to be very inexpensive. I was hoping to utilize either an MC34063A, a UC3525A, or something similar, maybe with gate drive circuits added, and maybe two of them for two-phase operation (if they can be synced that way and if it’s cost effective). But I have found very few application notes related to this type of thing. I’m looking for a control IC that’s under a dollar, if that's possible. Can you suggest anything for this application? Thanks!

  • 0
    TI__Genius 13660 points

    Hi Mike,

    In my opinion, both MC34063A and UC3525 are not suitable for this high output current application, because they don't feature the synchronous function, which will cause a large power loss.

    The reference design PMP10979 is closest to your requirement, which I can find. But maybe the device LM5119 exceeds your cost budget.

    The PMP10979 is a highly efficient, multi-phase synchronous buck power module. The input voltage range is 11V to 24.30V, with an output of 13.50V at 95A. The design is intended for automotive applications.

    http://www.ti.com/tool/PMP10979  

    http://www.ti.com/tool/PMP20804  

    You can also use the multi-phase synchronous buck converter, such as the controllers  LM25119

    http://www.ti.com/tool/PMP9700 

    Regards,

    Teng

  • 0 in reply to Teng Feng
    Prodigy 50 points

    Hi Teng,

    I was thinking maybe a synchronous rectifier IC could be used with the inexpensive IC, and still cost less, but maybe that's not practical? (Have to add gate driver(s) too I suppose). I'll check out the PMP10979 circuit. Glancing at the schematic, it looks expensive, but I'll check on that. Thanks!

    Mike