Question about Darlington Arrays

haunteddansion

Hi, I have the read the nuts a volts article about darlington arrays but Im still not sure where to hook up pins and power to the array and how much voltage it takes to function. could it funtion on 3 volts 50 ma? then output to something 300 ma and 9 volts. I am trying to wrap my head around what it does, it is like a set of low voltage relays because that is exsactly what I need. Also does anyone have a wiring diagram for a beginner like me to understand how to hook up the darlington with power and pins etc. Thanks much

-Dan

Chris Savage

Dan,

·· You didn't specify which Darlington Array you were referring to.· But in reference to the ULN2003 and ULN2803, these devices do not require power.· The V+ terminal has a very specific function which is not to provide power to the ULN, but to provide a connection to the + power connection of the connected device to connect the internal clamping diodes.· These are usually connected only to inductive or noisy loads, such as relays, solenoids or motors, and serve to protect the Darlingtons from back EMF from the load.·

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Jon Williams

As Chris indicated, what the ULN2x03 does is switch a circuit to ground through a Darlington pair -- this lets you complete a circuit that has the other side connected to the positive supply. Keep in mind that there is a bit of a drop across the transistors, so if you use 3 volts as your supply you'll actually end up with about 1.8 or so through your device.

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Jon Williams
Applications Engineer, Parallax