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LM5088: Question on the synchronous and non-synchronous buck controller

Joshua Kim
Intellectual 590 points
Part Number: LM5088

Dear,

I have a general question on the buck controller technology related to the LM5088. 

I am designing a circuit with the LM5088 buck controller, with which I noticed that I could get well over 90% efficiency for my intent.

This LM5088 is non-synchronous buck controller, while the vast majority of synchronous buck devices show off their superior efficiency.  

Would you help me to resolve my questionnaire?

Q1. If the synchronous buck technology is always superior to the non-synchronous, why semiconductor manufacturers like TI still retain the non-synchronous lines?

Q2. The LM5088 provides satisfactory efficiency to me. As far as the efficiency concerned, to what application I should employ a synchronous-buck controller?

Thanks,

Joshua Kim

  • 0
    TI__Mastermind 23845 points

    Hi Joshua,

    Yes, i can see that you are inquiring the difference between non-synchronous and synchronous buck technology. 

    In general, the non-synchronous technology comes earlier compared to synchronous one and sometime customer prefer this one due to pricing. 

    In terms of efficiency, yes at higher load current the synchronous buck will show its benefit in terms of efficiency since it is using a low side FET instead of a diode. 

    At light load, a non-synchronous buck might be more efficient since most of the losses at light load is switching loss and you dont have to switch the low side FET. This is why even a synchronous buck controller operates in diode emulation mode to gain some efficiency at light load. 

    Another thing that you can compare is thermal performance between the two topology. Due to efficiency, you might want to choose one over the other

    In general,  TI offers a broad range of selection of non synchronous and synchronous buck controller. You can select your solution based on price, size and performance that you desired.

    If LM5088 provides a satisfactory efficiency for you then it should be ok. If you further increase the load current then you might want to use a synchronous buck controller instead

    Thanks and i hope that answers your question

    -Arief

  • 0 in reply to Arief Hernadi
    Intellectual 590 points

    Dear Arief,

    Thanks a lot for the excellent answer, which cleared my questions.

    Thanks again,

    Joshua Kim