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ULN2003A: Using internal diodes for discharge current

Stefan Lintner
Expert 5105 points
Part Number: ULN2003A

Hello,

a customer of mine wants to use the internal diodes next to the darlington array of the ULN2003A to conduct the discharge current of an external capacitor.

Attached to the ULN2003A is a RC filter (100R, 100nF ceramic) which will be switched to GND by the ULN2003A. This filter is filtering a PWM signal of 20kHz.

Can the internal diodes be used to conduct the discharging current of the capacitor or is an external diode needed? Can a diode with an high forward voltage be used or is a shottky diode needed?

Thank you!

  • 0
    TI__Genius 10855 points

    Hi Stefan, 

    Thanks for reaching out on E2E! 

    Unfortunately, the internal diodes can't be used to conduct current. Some diodes, such as the collector-emitter diode, are parasitic structures. You can find more information on section 8.2, Functional Block Diagrams, in the datasheet. 

    A diode with a high forward voltage can be used, but I usually recommend using an shottky diode instead to discharge the current.

    Thanks,

    Arthur Huang

    To find the latest information on Power Switches, visit www.ti.com/powerswitch

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