Arduino pro mini - weird currents in VCC/RAW

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1

Hi all,

I have found something weird (at least for me) playing around with the Arduino pro mini (328p/16Mhz)

With a program like this:

void setup()
{
}

void loop()
{
}

When I connect a regulated 5v power to vcc/gnd, the current is about 50 mA. However, if I connect those 5V to the raw/gnd, the current is about 20 mA. I was expecting more current when I use the raw pin because of the voltage regulator.

What am I missing?

Best,

--
Limon18

2

My guess is that 5V is too little and it has not left reset, and thus is not drawing much current.

3

My guess is that 5V is too little and it has not left reset, and thus is not drawing much current.

Hi Nick,

Thanks for your guest. Anyway, I have just tried the following code:

void setup()
{
  pinMode(13, OUTPUT);
}

void loop()
{
  digitalWrite(13, HIGH);
  delay(1000);
  digitalWrite(13, LOW);
  delay(1000);
}

and the led is blinking either ways (connected to VCC or RAW). And the current is more or less the same...

4

So it's not 20mA/50mA?

This doesn't seem to be an installation issue then.

5

So it's not 20mA/50mA?

This doesn't seem to be an installation issue then.

Nope, still:

VCC - 50mA
Raw - 20mA

6

There is going to be a voltage drop through the voltage regulator (the "drop-out voltage"). Thus it is running on a lower voltage when you put 5V into RAW.

Can you measure what VCC is when you power it via RAW?

7

If you exceed the regulator's output setpoint, it generally functions as a (very tight) Zener.

8

There is going to be a voltage drop through the voltage regulator (the "drop-out voltage"). Thus it is running on a lower voltage when you put 5V into RAW.

Can you measure what VCC is when you power it via RAW?

It is about 4.70V