Dear Team,

I am connecting the output of a buck-boost converter(3.7V to 5V) to LDO.I am getting the expected output at buck-boot,but LDO output is not coming as expected.
I am attaching the simulation file also here.
Could you please help me.

 

hi hoy,
Simulating the two models, ADP 21.. and 75 individually shows that they both work OK.
However, when running the two models in the same simulation, they will not run as expected.
I have tried various component edits but without any success.
It appears that there is a timing problem between the two models???

Which version of LTSpice are you using?
E

 

Hi Eric,

Please see my version below.

 

hi hoy,
I tried that 64 bit version, I had so many problems I switched back to Version XVII
I know some other members had problems with x64.
E.

 

hi hoy,
This 10mSEc simulation took over 2 hours, I guess it will finally reach the required outputs.
E

 

Thank you Eric.
May I know this is the issue with Ltspice or spice model

 

hi hoy,
My Post #2, showing the individual acceptable performance of the two models, suggests that LTSpice is the problem.
If you check the full circuit, you will see the simulator is taking approx 1sec to evaluate each 2-3usec calculation.

E

 

I was able to speed up the sim at least ten times by reducing all the Spice sim tolerances by a factor of 10 (below).
This, of course reduces the sim accuracy, but that likely is not critical for this circuit.



Below took about 15 minutes on my old, moderate speed laptop:
The results seem very close to those shown in Post #5 which used the default tolerances.