analogWrite 255, but not getting 5vDC

[skjermlue]

Hello,
This is my code:

void setup() {
// put your setup code here, to run once:
pinMode (9, OUTPUT);

}

void loop() {
// put your main code here, to run repeatedly:
analogWrite(9, 255);
}

When I'm measuring between GND and pin 9, I am getting 4,87vDC.
Why am I not getting 5vDC?

[pert]

What do you measure on the "5V" pin?

[skjermlue]

pert:
What do you measure on the "5V" pin?

I tried again today, and now I'm getting 5,15vDC at analogWrite 255.
I'm also getting 5,15vDC on the 5V pin..
What's happening?

[missdrew]

How are you powering the board when you measure? If it's with the USB of the PC 4.85V - 5.15V is within specification.

[hammy]

The analog output is always a proportion of the 5v supply , so 255 = supply voltage.

[skjermlue]

missdrew:
How are you powering the board when you measure? If it's with the USB of the PC 4.85V - 5.15V is within specification.

Yes, it's via the USB of my laptop. Ok.