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24V, 15A Buck converter Design

Dear Expert,

I would like to make a buck converter with the following specifications.

Input range : 48V Norminal ( 26 ~ 140V )

Output : 24V, 15A

Are there a proper design that meets the above specifications using LTC7810 or proper chip?



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  • Hi Eui-heon

    1. Is there any reason apply the LTC3639 to EXTVCC in the DC2641A ( that is a demo circuit of the LTC7801? 

    It is used to supply the DRVCC Regulators instead of the  internal LDO to supply it.

    2. Is there any reason using two or more in parallel instead of a single type when selecting the FET of a converter with large current capacity?

    as Seth said, it is a way to dissipate the heat generated by the switches. Another way is connecting two or more regulators in parallel with their switching shifted out of phase of each other.

    To hasten your development time I would suggest using LTpowerCAD to verify your design. 



  • Hi Mikee

    1. Is there any reason apply the LTC3639 to EXTVCC in the DC2641A ( that is a demo circuit of the LTC7801? 
    It is used to supply the DRVCC Regulators instead of the  internal LDO to supply it.

    With the current configuration of the DC2641A, with  LTC3639 Vprg1 to SS and VPRG2 to ground so ETXVcc=5V, and DRVSET to 80K resistor (8V in DRVCC), and NDRV tied to DRVCC, wouldn't that still be supplying the 8 volts of the gate driver from the internal LDO?

    If this is the case, what would be best, lowering DRVcc to 5V? or increasing ExtVcc to 8V?



  • Hi Frank

    Yes, DRVcc is used as the gate drive source for the bottom FET but for the top a charge pump can be used instead. Please see block diagram on page 11 of LTC7801 datasheet

    Please use table on page 23 of LTC7801 datasheet as reference to set the desired DRVcc

    To increase ExtVcc, you would need to modify the feedback resistor/s in the case of DC2641A R32 and/or R34 .