Part Number:TPS50601-SP
Tool/software: WEBENCH® Design Tools
Using Webench for a TPS50601 design. My Webench generated design has one 47 uF output cap, ESR = 35 mOhm.
I wanted to add more output caps in parallel, so I used the "create Custom Part" to force the quantity to change from 1 to 3. The schematic properly shows the output cap as 47 uF, qty = 3. But when I go to the Re-Comp feature, it shows Cout in the Power Stage Components as 47 uF with 11.67 mOhm ESR. Thus the tool appears to be dividing the ESR by 3 as I expected, but the total capacitance stayed the same. I expected is to be 141 uF.
Is this a bug in the Re-Comp tool? If it is, is this also impacting the phase/gain margin calculations shown in the Ops Val results? The margin results did change after adding the output caps, but I don't know if this is just because of the ESR change or if the correct total capacitance was included. If I manually enter 141 uF for the Cout value in the Re-comp tool, I get a different phase/gain margin result.