A ULN2803 can drive up to 500ma per gate. 8 Driver per 18 pin dip.


Wagner Lipnharski wrote:

> Philip Galanter wrote:
> > Much more of a programmer guy than a hardware guy, and still a bit
> > new to PICs, so sorry if this is a trivial question...
> >
> > I am working on using 4 hardware PWM outs on a 18F-something to drive
> > 4 LEDs using pulse-width to control brightness.  And I need to make
> > them as bright as possible when they are full on.
> >
> > I think I may run up against current limitations sourcing/sinking the
> > LEDs straight from the pins, so I could use some transistors to drive
> > the LEDs.
> >
> > But rather than using discreet transistors is there a single DIP
> > package of some sort I could substitute?  4 independent drivers would
> > be optimal...
> >
> > thanks, Phil
>
> Phil, do you already know how much current do you need for those LEDs ?
>
> Remember that some microcontrollers, and I suspect PIC is in the list, can
> drive or sink around 20mA per pin, tops 100mA or 120mA per chip (using pins
> in parallel).
>
> I used an AVR to drive 2x IR LEDS, 6 port pins in parallel, I can drive
> 100mA easily to those light beasts...
>
> Wagner.
>
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