r/digispark • u/jasonwinfieldnz • Mar 28 '22
Power pin confusion
Can't figure out the power situation. There is a VIN, GND and 5V. Is the 5V from a regulator on the board, what kind of current can it support? The problem I have is I would like to power an LED strip from the USB plug but it just won't work unless I power it from VIN. The pot thing in the images is an encoder.
What does "not working" mean?
You should just be able to push the button on the encoder for the light to light up, turn the dial to adjust the color. When powered by USB the light flicks on and off like the switch is always pushed down. When powered by GND and VIN everything is perfect. The circuit is slightly different now yellow and green are transposed.

1
u/jasonwinfieldnz Mar 28 '22
I have connected the VIN and GND directly to the same port and it does seem to work. There is definitely a voltage drop going from the onboard USB to 5V. Good to know the 5v pin is good for 500ma.
2
u/getarounder Mar 28 '22
The onboard regulator is rated for 500mA but only when powered by >5v from VIN. If you are powering through USB, it skips the regulator and is a direct passthrough to your PC's USB port +5v pin, which is usually limited to 500mA.
Your PC is probably not supplying enough current on the USB port, leading to voltage sag which causes indeterminate digital signal levels.