I am designing a device, and I want to be able to power it with either USB, or a 5.5mm DC plug.
I'm just wondering how I should implement protection in case someone accidentally plugs in both cables.
I am using a standard 5 pin micro USB jack, and a 3 pin 5.5x2.5mm DC Socket.
Thanks
What is Your "device"? If it is an UNO i would suggest gluing a mechanical shield to the USB connector that couvers the DC plug connector. Than only one them can be connected.
Custom Board, with an Atmega32u4, Attiny13, and 4 Atmega8s.
Don't want to go into too much detail, I plan to eventually take it to kick starter.
I may switch to an ARM chip with more than 1 core instead of using all of those, but so far that's what I've got planned.
Keep it simple has been said in many different environments. Don''t cross the river to find water we saye here.
Just arrange the plugs in a way that only one can be connected. A sliding door giving access to only one plug at the time.....
Don't make it rocket science if it csn be awoided.
Yeah I was thinking about removing it all together, if someone really wanted to plug it into the wall they could use a USB wall adapter.
I have a bunch of AQH2223 Solid State Relays, but I'm not sure if it would switch fast enough to avoid damage.
Two Schottky diodes, one each in series with each supply is all you need. Supplies on the anodes, cathodes connected together and is the common supply point. The highest voltage supplies the current.
If you’re using AVR devices and you want to avoid the 0.3 volt drop created by the diode in the usb supply, look at the Uno R3 schematic. It uses a voltage comparator and a mosfet to disconnect the usb supply when it detects the barrel jack has more than about 7 volts present.
Solid state relays are totally inappropriate for the switching required.
LittleRain:
I am designing a device, and I want to be able to power it with either USB, or a 5.5mm DC plug.
I'm just wondering how I should implement protection in case someone accidentally plugs in both cables.
That is much the same as how the Arduino UNO, Mega, DUE etc are powered.
Did you check out thier schematics ?
srnet:
That is much the same as how the Arduino UNO, Mega, DUE etc are powered.Did you check out their schematics ?
I should have sooner, turns out I have all the same parts. Doh.