Tool/software:
I've been working with webench and the calculators provided on the device product page and find a discrepancy in the results.
The goal is to have a stable, 2-phase 13V to 5V converter at 35Amps
I first run webench with the following inputs and configuration changes:
Input DC 11V - 15V
Output 5V at 35A
User Preferred Frequency: 1.1MHz
Compensation Loop Gain Via Pin Strapping: ILoop:7, Vloop:2.0
Softstart: 3msec
Number of Devices: 2
Device Address: 37d
Sync Freq: Sync Out
See attached webench export
When I use the excel tool to replicate the design, all of the VLOOP Gain options turn red for the pin strap options. (see attached)
This indicates that there are no pinstrap options with the output capacitance produced with webench.
If I increase the output low-esr capacitance significantly (500uF) the table indicates many available pinstrap options with green/green.
If I add this much capacitance in webench and generate an output, the plot shows it to be stable, but phase takes a deep dive toward zero around 2kHz.
I'm planning to add the 500uF low ESR capacitance to my design. This will give me the most flexibility.
My problem is that webench produced a design that the excel tool indicates is not stable with any pinstrap options.
I would appreciate guidance on the use of these tools and what is the most reliable design method.
Thanks!
