Jacek Konieczny

I don't trust these models Neither do I. What about using the TI model of LM1117? Simulation was o.k. immediately. And once again, Holger to the rescue :-) I was looking for a TI model but could not find it, probably because I was looking for 'NCP1117' and not 'LM1117'. Output voltage is Vout=1.25V*(450/100+1)=6.875V Yeah… that is my mistake, which I managed to make twice today (and fixed once already). R1 was supposed to be 150Ω Thank you.

KiCAD circuit attached. Expected output voltage is 5V, but the simulated output is higher and highly dependent on the input voltage.

Hi, I got some success with DC-DC converter modeling and design and I just wanted to add an LDO regulator at the output for filtering. I have chosen NCP1117 (adjustable version), as it was cheap and available (first I designed with TPS7A4701, and simulation worked well, but then I saw the price of the chip). PSpice model is available here: https://www.onsemi.com/products/power-management/linear-regulators-ldo/ncp1117#technical-documentation But I was not able to make it work under KiCAD + ngspice...

Look just a few messages up in this thread: https://sourceforge.net/p/ngspice/discussion/133842/thread/9490acf90d/?limit=25#193a Linked examples include MC34063 circuits. Now I got to cases where those models do not work well… but I guess still good enough. I will know when the circuit gets manufactured. :-)

For now I have settled on using MC34063. It is not the best chip out there, but is easy to use (until more than 700mA is needed), simulates great in ngspice with the models that Holger provided and seems to be enough for my use case.

Could you please post your NGSPICE netlist? here: .title KiCad schematic .include "TPS54331_TRANS.LIB" .MODEL DN5819 D BV=5.33E+01 CJO=1.44E-10 EG=0.69 + IBV=6.00E-04 IS=1.65E-05 M=.671 N=1.41 RS=4.47E-02 + TT=7.20E-11 VJ=1.45 XTI=2 .save all .probe alli .tran 1u 5m .options method=gear rshunt=1e12 chgtol=1e-11 reltol=0.01 V1 /in 0 DC 15 C1 /in 0 4.7u R2 /en /in 332k R8 0 /en 68.1k C8 /in 0 4.7u R6 /VSENSE /out 10.2k C4 /out 0 47u C3 /out 0 47u R1 0 /out 1k XU1 /boot Net-_U1-COMP_ /en 0 /PH /SS /in...

With the .tran and .options lines .tran 1u 5m .options method=gear rshunt=1e12 chgtol=1e-11 reltol=0.01 in a text box on the Eeschema canvas, I have got the simulation of Fig. 13 up and running With those .tran and .options lines I managed to get the simulation running too (thanks again!). Then I fixed some obvious errors in my circuit. Unfortunately the simulation results are still wrong – I get much higher output voltage then expected (10V instead of 3.3V) and it is not even stable. I guess it...

On 6/23/23 18:42, Holger Vogt wrote: There is a bug in the TI TPS54331 device model, as it references a diode with model name MBR340, but the corresponding .model line is not given. I have noticed and fixed (hopefully properly) this one. If you simulate a power supply, with usually higher voltage then in IC simulation, you might consider some options to relax the precision requirements. Also the GEAR integration method sometimes has advantages. You will have to experiment a bit. I have been experimenting...