How can I bypass Arduino's voltage regulator?

I have a switching regulator running my ‘BOB’ robot, and the Arduino is actually regulating the regulated power coming out of the switching regulator; I don’t want that because when my battery gets down to about 8.5V the ‘double regulation’ drops down the voltage and causes the Arduino to reset. How can I bypass the Arduino’s regulator without having to use the bare ATmega168 by itself taken out? :-/

Connect your regulated 5 V (I’m assuming your first regulator is a 5 V one?) directly to the Arduino’s 5 V line. Leave the VIN (or whatever it’s called on the Arduino) disconnected.

  • Ben

Since you say your battery gets down to 8.5V, I assume you’re using a 9V battery. The Arduino uses a low-dropout regulator so it should be fine down to about 6V supplied to it.

What is the output voltage of your switching regulator? If it’s over 6V, you’re going to fry the ATMEGA chip if you connect it directly, and if it’s under 6V, you’ll probably have probably regardless of the battery’s terminal voltage.

What kind of switching regulator are you using? I wouldn’t have expected 8.5V to give you a problem with a switching regulator. With a linear regulator you might be running into problems (the common 7805 is a linear regulator).

I am using a 9.6V RC Ni-Cd rechargeable battery pack. Ok; I need to use the switching regulator for ALL power; that means the servos, and electronics (including the arduino). I need to get the most efficiency I can out of my 9.6V battery pack. I CAN’T use the onboard LDO regulator on the arduino to regulate all power, or even regulate the 9.6V while the switching regulator does the regulating for the servos and all other components except the arduino. I need all power to come from solely the switching regulator, and I need to bypass the arduino’s LDO regulator. Is there a way?

Yes, yes there is. Look three posts above this one for your answer.

Oh crap. I’m sorry; I didn’t see that. I’ll try it, then!