looking for advice for power solution:
My current project uses relative huge current (up to 500mA) on 5 Volts. Because whole project will be powered from 12V lead-acid battery, powering arduino and connected periferials from onboard linear regulator (AMS1117) is almost impossible due to high overheating (could be destructive in summer days) and also huge power loss - this makes linear regulator unsuitable for battery powering in wide temperature range.
I dont like linear regulators at all, mostly using DC-DC step-up/down converters to enhance efficiency and lower the power dissipation & power losses.
Because I have several 12V to 5V stabilized step-down DC-DC converters. But they cant be connected to Vin pins, because these lead to linear regulator which makes big voltage drop.
So, my deduction is this - please correct me if I am wrong !!! :
Onboard linear regulator is 5V fixed and its output should be connected to 5V pins and CPU itself. All 5V pins are connected together.
Question is, if this above is true, could I connect stabilized 5 Volts from DC-DC converter to Arduino 5V and GND pins? No other power source will be connected of course.
In theory yes, but I think there is an issue with the linear regulator on some
boards not liking being reverse-powered and sinking lots of current. Check it
out with a multimeter?
Be aware that DC-DC converters will likely cause a few LSBs of noise in the
output of analogRead(). You might be able to use the DC-DC converter for
the parts of your circuit that takes a lot of current and supply 12V to the barrel
jack of the Arduino so it runs off its regulator (takes about 35mA alone which
isn't much compared to your 500mA load).
You could use an adjustable buck converter to produce the minimum input voltage (7 V) for the Arduino barrel jack. That would be reasonably efficient, avoid ADC noise and eliminate possible problems with "reverse-powering" the on board regulator. An example: Pololu Step-Down Voltage Regulator D24V6ALV
MarkT:
In theory yes, but I think there is an issue with the linear regulator on some
boards not liking being reverse-powered and sinking lots of current. Check it
out with a multimeter?
Thanks for note!
I didnt have multimeter at time of writing of first post. Now I am home and checked that Arduino 5V power pin is connected directly to the regulator output. Ground is shared also, of course.
So it mean, that it could be done, i will try it with regulated supply with double fuses and resistor, jus for double sure if something goes wrong....
MarkT:
Be aware that DC-DC converters will likely cause a few LSBs of noise in the
output of analogRead().
I am counting with it. As my project is super high precision measuring device, which measures precison analog voltages in milivolts. Several samples are taken during second and then processed with some funky mathemathics
Because interference immunity is hence very important, I have ferrite cores on all wires. Just for case.
MarkT:
You might be able to use the DC-DC converter for
the parts of your circuit that takes a lot of current and supply 12V to the barrel
jack of the Arduino so it runs off its regulator (takes about 35mA alone which
isn't much compared to your 500mA load).
Good idea, if everything elso goes bad
Will checkif 5V output asi input works first... Hope it wont burn something...
I remembered one solution about wich I heard with good ol LM317 in security systems. There was also often battery connected behind linear regulator.
Found it, because I knew there was just diode
It looks like this:
It should work, but never tried it. according to source: "D1 is a general purpose 1N4001 diode, used as a feedback blocker. It steers any current that might be coming from the device under power around the regulator to prevent the regulator from being damaged. Such reverse currents usually occur when devices are powered down."
I will give it a try as this looks like the most effective solution
What do you guys think?
I also must hope that principe of operation of AMS1117 is similar like LM317 - didnt found its internal block schematics....
