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Description: 8 Darlington Arrays in 18-Pin DIP Package part # ULN2803A. Perfect for running relays and high-power devices up to 500mA and up to 50V!

Resources: Nuts and Volts article on Driving High Current Loads

Documents: ULN2803A Datasheet

Comments 24 comments

  • In the description, ADD the word transistor so it shows up when you search for a transistor.

    I feel like a lot of times I’m never satisfied with Sparkfun search results. Maybe I’m spoiled by google.

  • Does this come with a housing to be soldered on to a PCB? Do you sell them?

  • ULN2803 current: shared or per output?

    Hello, one question. ULN2803’s datasheet says “500mA output”. So my question is: Those 500mA are: a) per each single output? (500mA each output, so paralleled the 8 outputs will draw 500mA*8=4000mA?) b) shared per the whole chip? (500mA/8 outputs= 62,5mA per output)

    • If I read the data sheet correctly, the rating is per output.

      • There’s a line in the datasheet, though, that reads “Total substrate-terminal current … −2.5 A,” which leads me to believe that you can switch up to 500 mA on each pin, but can’t sink more than 2.5 A total. So if you want to switch 4 A continuous, you cant do it with (just one of) this chip, but if you had 8 loads of 500 mA each, and didn’t turn more than 5 on at a time, you’d probably be OK.

  • Can I drive these directly from any arduino? (5v) And how is input mA related to output current/voltage? Are these capable of switching fast enough to allow pwm? I’m new to reading datasheets…

    • According to the datasheet, the “typical” Low-to-High transition takes 130 ns. H-to-L is typically 20 ns. Round up, call it 200 ns, and you can cycle these darlington pairs at about 5 MHz. If you’re doing PWM for LEDs, then you would typically use a mere 100 Hz.

  • Sorry if this is a dumb question, but I’m new with this stuff. If I connected the common pin to ground would I be able to connect each of the collectors to ground and drain current?

  • Will these work for switching high-power, 3V LEDs from a 5V control source?

    • I use mine with the PWM pins on my Arduino Uno to control an RGB LED strip, so I would think you would be alright as long as you don’t exceed 500mA.

  • Anyone know if I can drive this directly off 3.3V? Works great with 5V, and the pinout lines up perfectly with the Pro Mini.

  • Can this be used to drive motors?

  • I think if you use it as a high-side, you’ll end up getting latching like a thyristor…. you cant turn it off.

  • I dont think you can use these as a high-side switch. If the load is any bit reactive, you’ll have latching problems…I think… most chips that are high side are marketed as exclusively high-side

  • Can NPN darlingtons used as a high side switch? If I connect the collector to 5V and the base as well, what will be the emitter voltage? <br />
    <br />
    According to the datasheet Vce(saturation) is 1V, so would that mean that at the emitter the voltage is 4V?

  • do you have eagle library for this too??

  • Could anyone give me some advice whether I could use this with a TI Launchpad to drive “blocks” of LEDs in parallel. Looking to make a table with LED effects and so just want to be able to switch between 6-8 blocks of parallel LED arrays. Problem is, TI output pins are only 3.3V…none of the LED arrays require more than 500mA and have voltages of say 12V.


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