I've made a layout around an Allegro A4490 triple buck regulator, with four optimization goals:
- minimize loop area/change in area when switching
- keep the ground attachment of the input and output capacitors and the flyback diode together
- avoid cutouts in the ground plane, and at least keep deviations for return currents short
- prefer vias in slow signals with small current (i.e. the "enable" and "power on reset" traces)
I have two fixed voltages, and one that can be adjusted using a potentiometer; in addition the outputs can be switched individually, or a jumper can be used to keep them on, and an active-low reset signal is generated when the supply is outside the target range.
As a result, I now have a layout where a trace runs through the middle of a 0603 capacitor, which limits the trace width to 0,3mm:
- Do I want to change the layout so I can have wider traces, or is that irrelevant anyway because of the pad size?
- Is there a downside to running that trace below the capacitor?
- The datasheet allows up to 2A on the output side, however I'd presume I need to account for more on the LXn traces (i.e. the FET output). How much more?
Last, if there is a glaring error in the design that immediately jumps at you, I'd like to know.