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LM5170: Buck-Boost Converter

d_zero
Genius 4775 points
Part Number: LM5170
Other Parts Discussed in Thread: LMG1210, , LM5155, LM5156

Dear *,

is it possible to design a buck-boost converter with 1x LM5170 and LMG1210  to have Vout_max = 200V ?

Best Regards,

David.

  • 0
    TI__Guru* 78270 points

    Hi d_zero,

    Thank you reaching out.  The answer is possible but what is your input voltage range?  If the voltage range is beyond 65V, you may need INA part to help sense the inductor current.   Also, what is the max power that you are targeting at?

    Thanks,

    Youhao Xi, Applications Engineering

  • 0 in reply to Youhao Xi
    Genius 4775 points

    Hi Youhao,

    Input voltage range is from 12V to 24V.

    for continuous out power we wan to try two cases:

    1) Max out power 24W ( for Vout voltages from 0V to 12V Iout_max = 2A, for Vout voltages from 12V to 200V Iout_max= Poutmax( 24W) / Vout))

    2) Max out power 96W ( for Vout voltages from 0V to 48V Iout_max = 2A, for Vout voltages from 48V to 200V Iout_max= Poutmax( 96W) / Vout))

    Best Regards,

    David.

  • 0 in reply to d_zero
    Genius 4775 points

    Hi Youhao,

    can you tell what would be the max power output that we can achieve with LM5170 ?

    Input voltage range is from 12V to 24V.

    Best Regards,

    David.

  • 0 in reply to d_zero
    TI__Guru* 78270 points

    Hi David,

    If your input is 12-24V, and your output is 24V, you will have to design a DCM boost with the LM5170, because if 200Vout requires 94% duty for CCM and you will have not leave enough time to transfer the energy to the load.

    However in your design, why do you want to use the LM5170?  Please take a look at our LM5155 and LM5156.  These two are similar parts, and the LM5156 has spread spectrum feature to help mitigate EMI which may or may not be a concern in your design. 

    Regarding the max power, the LM5170 has very strong drivers, 5A peak vs 1.5A peak in the LM5155/56.  We do have customer using the LM5170 to support greater than 1kW in dual phases. However, this seems to be irrelevant to your case here, because you are using LMG and the strength of the LM5170's driver does not matter much.  What you need is a PWM controller and the LM5155 and LM5156 is good enough in my opinion, and they can also support up to 2.2MHz switching frequency to leverage GaN FET's speed capability.

    Thanks.

    Youhao