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I had conneced my digital pin of arduino to the uln2803a to drive LED. I want to configure my uln2803a such that i can connect +ve side of the led to the output pin of uln2803a IC.

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  • \$\begingroup\$ It can be done, but it's a very inefficient way to drive the LED. Is there a particular reason why you have to drive the +ve side? What is the LED supply voltage? What is the LED current you want? Can you invert the sense of the Arduino drive signal? \$\endgroup\$ – henros Jan 10 at 16:30
  • \$\begingroup\$ I want to make a led matrix.I have shorted anode row wise and cathode column wise .Now I can only control the cathode side by using ULN2003 not the anode side of the matrix. \$\endgroup\$ – Atharva Gorule Jan 11 at 3:09
  • \$\begingroup\$ Supply voltage is 5V and current is 10mA \$\endgroup\$ – Atharva Gorule Jan 11 at 3:10
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ULN2003 only sinks current (connects load- to Gnd). It does not source current (connect load+ to +5). For that, you need a part like MIC5891, which is a shift register with high current source outputs. https://www.digikey.com/product-detail/en/microchip-technology/MIC5891YN/576-1310-ND/771779

If you don't need that much current, or the latch capability from the shift register, then a line driver such 74AC541 can drive 24mA loads https://www.digikey.com/product-detail/en/texas-instruments/CD74AC541E/296-4248-5-ND/375631

Or other parts in the 74AC family if you need something in a smaller package https://www.digikey.com/products/en/integrated-circuits-ics/logic-gates-and-inverters/705?k=74ac&k=&pkeyword=74ac&sv=0&pv69=80&sf=1&FV=ffe002c1&quantity=&ColumnSort=0&page=1&stock=1&pageSize=25

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ULN2003A cannot be used as a high-side driver, however you can use it to drive a PNP transistor or a MOSFET per channel.

schematic

simulate this circuit – Schematic created using CircuitLab

Pick R2 to give about 1/20 the LED current to the base and pick R1 something like 1K to prevent leakage from turning the transistor on.

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  • \$\begingroup\$ What about M54562 \$\endgroup\$ – Atharva Gorule Jan 10 at 17:39
  • \$\begingroup\$ The M54562, if you can find it, is a sourcing array and can be used. The voltage drop is fairly high. There was also a UDNxxx part from Allegro (Sprague orginally) and another from Toshiba, I think all discontinued now. \$\endgroup\$ – Spehro Pefhany Jan 10 at 18:48
  • \$\begingroup\$ I didn't know about sourcing and sinking array \$\endgroup\$ – Atharva Gorule Jan 12 at 2:49

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