Dash Power Switch Viable?


#1

I’m designing a device using the Dash with several peripherals (display, battery backed RTC, accelerometer, sound player). To facilitate shipping and air travel, I plan to put a power switch between the battery/power supply and the Dash to cut all power when it’s off. Generally, powering on the Dash seems to start the firmware running, though I have to do some more testing.

Anyway, has anyone else tried something like this? I’m particularly wondering if connecting both the battery and external power at the same time through a switch could cause problems (I’m planning to use a DPST switch on the positive side of both sources).


#2

The concern is a race condition between an external power source and the battery or something?


#3

Thanks for following up!

Yes. I’m working with only a modicum of knowledge on this. But, it seemed to me that there might be a race issue with both both sources connected at the same time. Also, that there may be a current surge which could cause issues. The plan is not to have an on-board regulator and go straight from a 5v power supply to the Dash. Then, from the Dash output voltage to the other modules. These won’t be field serviceable, so I’m trying to be extra paranoid and think of as many issues as possible in advance. :slight_smile:


#4

If you look at the Dash 1.2 schematic:

You see the battery hangs off the MCP73871.

I think since that charge controller is determining which power source to use, you should be fine in that case. I recommend reading more on that datasheet and determining if it will be a good fit for your application.


#5

Perfect! Thanks for the information. I’ll check it out.


#6

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