I made a board recently and just started checking it out yesterday. I used a typical lithium coin cell and a boost converter (Microchip MCP1640). With a battery plugged in I get no voltage out of the boost converter (i.e. 5V to GND measures 0V). Worse yet, I measure very nearly 0V from BATT_PWR to GND with the battery in circuit.
So I removed the battery and fed 3V from a benchtop power supply into the FTDI_PWR net and sure enough was able to measure 5V. The PSU indicated I was drawing about 50mA. I experimented with lowering the voltage, and the booster held 5V, but current draw increased as input voltage decreased (which I believe is expected).
So, is the peculiar battery behavior described above due to the battery current limiting? Is there likely to be some more insidious problem at work here - how might I determine that? If this is the wrong way to boost a coin cell to 5V, what's a better way?