Quick newbie question about programming the Arduino with a load on the 5V rail.

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Quick newbie question about programming the Arduino with a load on the 5V rail.

Hi.
I am running an Arduino that is normally powered from a 5V 4A supply, which is enough current for the LEDs I am using and the Arduino.
The LEDs are always connected to the 5V rail and a data pin for their signal.

My question is . . . can I just plug a USB lead into the Arduino and reprogram it WITHOUT the 4A supply running?
I am worried about blowing / damaging my USB port because of power demands on it.

Is it wise in this case to 1) Make sure the 5V 4A supply is on if programming the Arduino.
2) Take the Arduino completely out of circuit to program it, if I can’t turn that supply on when I need to program the Arduino.

Or is there some clever switching in the Arduino / on the circuit board that prevents this scenario.

Thanks everyone.

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I’d like to know this too, as I usually disconnect the arduino.

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Most computers will disable the USB port if power draw is too high to prevent damage. I’ve had this happen with my MacBook a few times when I had a short circuit.

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You can run the Arduino from USB power and the LEDs from an external power supply, with the grounds of both circuits connected.