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ADP2442 buck-boost simulation in LTSpice

Question asked by gcsipkes on Jul 23, 2018
Latest reply on Aug 2, 2018 by gcsipkes

Hello,

 

I am trying to simulate a buck-boost converter from 12V to -10V. I use the ADP2442 regulator model provided by the latest LTSpice version.

 

The output ramps down but then it flattens out at approximately -5.6V. I tried changing the feedback divider for other than -10V outputs but without results. As long as the output voltage set by feedback is above -5.6V (e.g. -4V) the supply works fine. This all happens with no load. For a load switch the supply enters in a current limiting mode precisely regulating the output voltage to Iout*Rout (about -4.4V=-550mA*8ohms) and continues switching without hiccups. The regulated current limit is far from the overcurrent condition.

 

Any possibility to have a bug in the ADP2442 model or am I missing something in the simulation? It should be noted that the exact same design has been built on PCB and is working without issues to output voltages down to -16V.

Please see the schematic attached for reference.

 

Thanks, Gabor

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