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ULN2003A: Pull-up Resistor placement for Resistive loads

Art Mecina
Genius 16655 points
Part Number: ULN2003A

Hello Guys,

Where does the pull-up resistor goes for resistive loads (leds) on ULN2003A?

It was mentioned on the datasheet but was not clear where it should go.

Our customer wants a solid logic-0 on output and a pull-up resistor is somewhat confusing.

Also, should he keep the COM pin floating for  resistive loads?

Thanks to confirm!

Art

  • 0
    TI__Genius 13760 points

    Hi Art,

    Welcome to E2E

    The ULN2003A is a low side switch meaning that it completes a connection to ground, and it cannot source current. In order for the device to work with an LED the anode of the LED must be connected through a pull up resistor to a power source, and the cathode to an out-pin of the device. Once a voltage is applied to the corresponding in-pin of the device, the ground connection will be complete and the LED will light up.

    The COM pin can be left floating as this pin is only used to suppress the voltage kickback from inductive loads.

    Best regards,

    Andy Robles