Hello,
I’m trying to make a custom board based on the Sparkfun board above (thank you for being open source - useful product!).
I’m running into the issue where I am hearing a twitching noise at high loads / low battery voltage meaning high current is being drawn from the battery. This is likely the cause of noise in my 5V line. I do not hear this noise on the Sparkfun Designed board.
My thinking is I have sourced a component with insufficient current rating which is causing this noise. I know the inductor is the biggest limitation - however I snagged the Inductor from the Sparkfun board and soldered it into my custom PCB with no impact - I also soldered in the 100k (1.6A) current limit resistor with no effect. Finally, the three 22uF capacitors I purchased are all 25VDC rated.
In addition, the traces on the battery line on the custom PCB were not wide enough initially (0.381mm) - however I manually soldered in jumper lines along all of these traces with no impact on the issue.
I have also removed all components from my PCB except C1,C2,C3, R1, R2, R4, R3, L1, and PAM2401 (labeling based on Schematic posted for part on Sparkfun page) - I still hear the noise at low battery power / high load that I do not hear on the Sparkfun board.
Any help would be greatly appreciated and have a great day 
