Hello,
I am designing a complex system which has three LM25119 in synchronous mode (fsw=500kHz).
First LM25119 is 1.8V@6A and 1.5V@6A. Vin 9 to 14V
Second is 3.3V@5A and 5V@2A. Vin 9 to 14V
Third feeds the other two, and it's 12V@10A. Vin 14 to 30V.
All the three designs were made with Webench, and for example, the 1.8V@6A in Webench, states a crossover frequency of 49kHz and phase margin about 70º, which is quite good.
When I put the values of the webench design into the LM(2)5119 Quick Start Calculator, the stability results are different. In fact, I've got about 40kHz as crossover frequency and phase margin of just 10º or less.
What is wrong? I put the same values in both designs (Webench and xls), and both designs are configured not to be 'diode emulation'.
Hope someone can help me.. :)
Thanks!
Best Regards,
Oscar
