LTC 3440 LTspice Simulation (using macromodel's test fixture) works w/ 100 ohm load resistor (0.033A) but not 13.2 Ohms (.25A)

In the default macromodel's test fixture for LTC3440, the default 100 ohms load works fine, output reaches 3.3V

100 Ohms (Default):

However, when I change Rload to 13.2V to test 0.25A output (which is under 600mA rating) then Vout stops at ~1.66V. 

13.2 Ohms (.25A)

Could I have any insight on how to remedy this?

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  • +1
    •  Analog Employees 
    on Mar 1, 2021 1:47 PM in reply to patsta

    Hello,

    the LTC3440 cannot change operation between continous mode and Burst Mode on his own, hence you have to select it 'hard' by proper use of MODE pin. Once you have selected Burst operation the output current capability is limited. You can see this from the efficiency diagram in the datasheet:
    Burst mode curve stops at 30mA Iout

    hence I would suggest a more modern BuckBoost regulator like the LTC3130.

    kind regards

    Markus