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APM2.5 5V/Vcc Schematic

Posted by R. D. Starwalt on October 26, 2012 at 2:27pm

Frequently asked questions are about powering an APM2.5 or why the same does not work or why it has failed.

Here is a simplified schematic showing the major components of the 5V/Vcc circuit on the APM2.5

Target Audience: Readers who do not have Eagle or are confused about using it.

You Need: Basic electronic schematic reading ability

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Note that I have separated the PWM Output section into the upper left corner with a heavy purple line that is bridged by the jumper JP1 on the APM2.5. This is to emphasize that diode D1 passes current through JP1 (and drops voltage). The remaining energy is then called 'Vcc'.  Everything outside the purple corner is Vcc.

This is why the USB will power the APM2.5 when connected to a computer/USB hub. Note the fuse on the APM2.5 side of the USB connector AND another fuse on the output of D1. Another change from APM2.0 is the D4 6.0V Zener diode. If an over voltage is applied to the board, D4 will crowbar what it can to protect devices.

As with APM2.0, any 5V source connected to any of the indicated Vcc/5V points outside the purple corner (with GND of course) will power the APM2.5.

Also of note is the 'Mystery Port'. This port takes 5VDC before D1 and the fuse and is called 'JP_VCC'. Other clues to the mystery are the lines to 'ADC 12' and 'ADC 13'. A mystery indeed!

Any errors in this drawing from editing are mine.

I hope this can be used as reference for solving problems.

-=Doug

 

27-FEB-2014 Eagle files are now located HERE

 

APM2_5 Simplified Power.PNG

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Tags: (uav)-autopilot-hardware, apm25
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Replies

  • vitaly November 24, 2012 at 4:33am
    ok do you think by powering the APM2.5 with the jumper JP1 on meaning that the power comes from the ESC could this be the cause of a failure of the board when a ESC synch is performed connect disconnect etc to the LIPO pack

    Is it not then advisable to have a separate supply maybe 3.3 v to the board to prevent this type of failure . my board doesnt communicate "connect" to the mission planner I notice just above the silkscreen IC2 a pin hole in that diode marker ..I guess...3.3 ???

    do you think further damaged could occur ???
  • vitaly November 24, 2012 at 3:15am

    I cannot connect any longer APM 2.5 to Mission Planner  Board is recognised baud rate set ok  but Times out 

    No Heat  spmething    message

    I notice that the diode just above the IC2 socket has a small pin hole    maybe blown  yet seems ok with multimeter 

    any one with the full schematic   

    I think the ESC calibration caused this  connect disconnect Lipo send spikes all over the board especially with jumper JP1 on   it would be better to power the APM with a separate supply  no ?   Am I wrong???   help 

  • Developer
    Craig Elder November 7, 2012 at 11:55am

    Thanks for posting this Doug!

  • Tim McPherson October 26, 2012 at 3:15pm

    Thanks again for helping to clear up and simplify/de-mystify potential questions.

    Tim

This reply was deleted.

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