Discussions

My intent with this diagram is to help those with moderate electronics knowledge (and by default those with greater skill) understand the APM2.5 Vcc/+5VDC connections. (click on it to see it larger)

Parts of the APM2.5 Eagle files were pulled together into a single file showing the major power connections. There are several other connectors that also tie into the +5VDC buss, but they are not part of this discussion.

HERE are the official 3DR recommended power supply connections.

The inspiration for this diagram was the robust 'discussion' in another section regarding the 'failure' of APM2.5 to boot unless connected to USB. Ignorance can lead to incorrect assumptions about a system. This little bit of knowledge might help someone understand or troubleshoot your system.

System is emphasized because the path of least thinking resistance is to blame the APM when things do not work.

Key Points to realize about APM2.5

• 500mA is the current limit of the fuses (2) for any bona fide input. Exceed that by shorting out a Vcc/+5VDC buss and it may open giving a 'dead set' symptom.
• 6VDC is the absolute maximum input supply voltage. Zener D4 will regulate overvoltages until it fails. After that, the fuses start blowing (if not before).
• The 'ESC 5V EN' jumper serves the same function as the jumper on APM2.0. If it is left out, APM2.x will only power up via USB or other connections as made.

Take care when connecting to any of the +5VDC headers. With 0.10 inch spacing, it would be very easy to short to the adjacent 0VDC (GND) pins if you are using test equipment (a test harness/jig is mulling around on my to-do list).

Message to 3DR folk: If something is glaringly wrong here, call me out on it and I will fix the diagram.

-=Doug