0miker0:
I created a small PCB design using a switching power supply part number TPS61200DRCR with a 4.7uH inductor LQH3NPN4R7N0L. The inductor is rated at over an amp but but design only draws 40mA. For some reason the supply sounds very noisy. When I blink and LED I can actually hear the supply on every blink. Today I'll view the output on a scope to see if it measures noisy as well. The input and output capacitors are all the correct values according to the data sheet. Has anyone ever seen this before?
Switching Power Supply design is an art unto itself. Little things like parts placement, component alignment, ESR of capacitors, connection lengths, wire/pcb techniques, all affect the supply and its operating characteristics.
Without pictures, exact part numbers and a schematic of the design, it is unlikely someone here, or anyone else could help you. These are very specialized skills.