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Recommendation for 12V-48V (8A) adjustable output SMPS

Jacob
Prodigy 180 points
Other Parts Discussed in Thread: LM5176

A customer has an unusual request:

For various motor brakes they need an 8A output with adjustable voltage in the range of 12V-48V, though those precise voltages are not set in stone. Preferably 1V steps.

The input is 24V +/- 20%, so about 19V-29V range.

Something like this: http://www.ti.com/lit/an/slva251/slva251.pdf - but of course with much higher output voltage/current.

I would simply do it, but I am worried about the compensation network not changing, as well as how hard it will be to EMC test. I'm thinking fixed-frequency would be preferable.

Does TI have a recommended solution, or just suggestions, for this application?

  • 0
    TI__Mastermind 46905 points

    Hi Jacob

    Thanks for considering TI device.

    From the input/output condition, you would need a BUCK-BOOST controller, such as LM5176. More detail about this device can be found in its product page. Let us know if there is further question.

  • 0 in reply to Jasper Li
    Prodigy 180 points

    Jasper,

    What makes the LM5176 particularly suitable do you think?

    Vout of course figures in many calculations, so I would worry about suitable component selection for all possible Vout values, stability with a single compensation network, etc.

  • 0 in reply to Jacob
    TI__Mastermind 46905 points

    Hi Jacob

    Considering the output power and thermal , buck-boost controller is the only solution.

    About the compensation components, normally we can design the compensation network based on the worst case, which is the boost mode (VIN lower than VOUT). Another solution is that using switcher to change the compensation network based on the input/output condition.

    This device has webench model and EVM, which will help to design the circuit and evaluate the performance of the IC. 

  • 0 in reply to Jasper Li
    Prodigy 180 points
    Unfortunately WEBENCH can't simulate this design for 8A out since it cannot find a suitable FET.
  • 0 in reply to Jacob
    TI__Mastermind 21720 points

    Hi Jacob,

    Please start with the quick-start calculator for the LM5176. This will allow for the inductor and the compensation to be tuned in as needed. From there the MOSFETs can be selected. To help increase the efficiency it should be considered to use 2 MOSFETs in parallel on the boost low-side. Please note that WEBENCH doesn't cover this functionality.

    Please let me know if you have any questions.

    Thanks,

    Garrett