I'm working on designing a PCBA which uses the STM32F446 as the micro. The issue I'm dealing with is that something seems to be shorted between 3.3V and GND, likely due to some fault with my schematic.
Things I've tried:
- 3.3V supply is known good with micro not populated. No excess current is drawn. Micro has been populated by board house so that is also known good. I tested a couple boards with the same result as well, so some manufacturing error can be ruled out.
- The micro is oriented correctly (I've been particularly careful about this because STM has a weird marking system).
- Resistance drops from ~5k to ~400 ohms when the micro is present.
- I grabbed the schematic and PCB footprint from STM, so that is also known good.
At this point I've ruled it down to an error in my schematic, but after poring over the datasheet I've been unable to find where that might be. Any and all help would be greatly appreciated. Please let me know if there's any more information I can provide.