pathfinder

I had some trouble after I first assembled that portion of the circuit, because we don't have the 0.047 µF or the 0.0047 µF 0805 caps. I tried it with 0.01 µF and 0.001 µF, but that didn't work. Then I found a 0.047 µF through-hole cap, bent and trimmed the leads, and it worked.

I also didn't have the exact resistors for R1 and R2 (43.5 kΩ and 6.19 kΩ, respectively), so I used 47 kΩ and 6.8 kΩ instead (20% tolerance). This results in a no-load output voltage of about 10.8 V, after it stabilizes. Initial voltage is much higher, but I suspect that's due to the no-load condition. When the MCU is connected, the boost converter's output stabilizes at about 10.05 V. The Fluke 111 DMM can't pick up the initial over-voltage in the time it takes to stabilize (I have not looked at it on the 'scope).

There's less than 50 mV of ripple (on Vpwr) at the MCU power input, and less than 20 mV noise after the LDO on the MCU. There's less than 200 mV of noise just after the DC-DC converter, although it increases a bit as you travel out along the trace, never more than 200 mV.

After the LDO on the MCU board, there's a clear 100 mV spike at 500 kHz.

Good job, John & Bobby, on designing the board!