Sinking current from 9V into a PIC pin.

[HankMcSpank]

Hi Joe,

My point was not what you meant.
If a PNP transistor is supplied by 9V, and you drive it with +5V (less than 9V), then the transistor will not be ignited as you expect.

As easy as having it tested on real circuit.
Just drive an LED via PNP transistor by a PIC, ON and OFF.
You will see that LED will not fully turn OFF.
And for the subject, our friend should use NPN, or for the easniness, use ULN2003, ULN2803.

The LED *does* turn off ! (ie the PNP tranny is working as I intended/required - real world, not simmed or theorized!) .....ie at a PWM duty cycle of value 255 the LED is visibly off (at a duty cycle value of 250 the LED light is just detectable...the LEDS continue to get brighter all the way to a duty cycle value of 0)

Re using an NPN....how would that slot into my needs of having a PIC sink the current per LED (in otehr words the suply voltage to the LED anodes needs to be commonised - how to switch that common voltage with an NPN?).

re using the ULN2003...I have no extra space available! (that's why I want to use a single, SOT23 SMT tranny to switch the 9V to the LEDS)