Take a look at the Allegro Drivers. Many allow you to interface to your
logic and supply the drive with another voltage. I am doing this with a
high side driver running at 12 volts controlled by a pic. The allegro part
I am using is a serial input 20 bit driver #5812F. I am sourcing at 20mA
but they are rated to a max of 40mA. Other parts can run higher. They are
located in Worcester MA and the phone # is 508-853-5000. They have a new
part coming that is designed specifically to drive LEDs but I do not know
its availability.


At 11:52 PM 2/27/98 -0600, you wrote:
>Hello,
>        I'm in the middle of designing a device that is going down into the
>deep, dark ocean. It's just a little quadrature encoder that is going
>on the end of a robotic arm to measure the revolutions of a torque
>tool. The problem I foresee is driving the LED's to really make them
>shine. Is there a device like the ULN2803 that I could use to drive
>the LED's to something higher than 25ma ?? The LED's are rated for
>30ma and I figure I can pulse them at something higher i.e. 50 to
>60ma. Of course I could do it with transistors but an IC would be
>more sanitary. I've been to all the local electronics shops looking
>for the 2803 or something like it. I've pulsed some IR LED's to 2 A
>with no adverse effects therefore I assume you can drive regular RED
>LED's at something higher than rated current. Any ideas ?? All help
>is appreciated.
>
>        Thanks in advance !!
>                                James Holbrook
>
>
Larry G. Nelson Sr.
mailto:L.Nelson@ieee.org
http://www.ultranet.com/~nr