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LP5036: Serial connected LEDs on OUTx

Claudius Fischer
Prodigy 50 points
Part Number: LP5036

Hi e2e Team,

I want to use two LEDs in a row connected to one OUTx pin on the LP5036. Is it possible to higher the VLED up to 9-12 volts if staying below the Output Maximum Voltage of 6V?

Thanks! Regards

Claudius

  • 0
    TI__Genius 9255 points

    Hi Claudius,

    We didn't suggest to operate the device when power VLED up to 9-12 voltage, please respect to the spec. Higher VLED voltage will damage our device when the LEDs happened unexpected shorted or there is some spike at the OUTx pin.

    Best Regard

    Monet Xu 

  • 0 in reply to Monet Xu
    Prodigy 50 points

    Hi,

    thank you for the answer. So what is the maximum allowed voltage of VLED? In the datasheet I don't see specified information about VLED.

    Do you see any possible ways to connect more than one LED to OUTx?

    Regards

    Claudius

  • 0 in reply to Claudius Fischer
    TI__Genius 9255 points

    Hi Claidius,

    Generally, we default that the VLED should be limited by the range of OUTs voltage for the reliability of device. So you'd better not exceed the maximum voltage of VOUT.

    Whether multiple LEDs can be connected in series is depended on the forward voltage of your LEDs.

    Please feel free to contact me if there are more questions.

    Best Regard

    Monet Xu

  • 0 in reply to Monet Xu
    Prodigy 50 points

    Hi Monet,

    so what is the maximum voltage of VOUT?

    Sure thing but if I use LEDs with a forward voltage of 3,1V I'm not able to use two of them in series when VCC is 5V. So my idea was to use VLED externally to increase the numbers of LEDs in a series connection.


    If this is not safe to use do you have a recommendation for another device capable of handling more LEDs in series? If possible with the same numbers of outputs and I2C communication.

    Thank you!

    Regards

    Claudius

  • 0 in reply to Claudius Fischer
    TI__Genius 9255 points

    Hi Claudius,

    The maximum voltage on OUTx can be referred on datasheet(7.1 absolute maximum ratings). VLED and VCC can be provided separately but high VLED will bring the risk to damage the device. So spec do not suggest to set VLED higher than 5.5V.

    for better recommendation could you please provide more information about your application?

    • how much leds do you want to drive in series per channel?
    • how much channel do you need?
    • input/output voltage
    • current range
    • dimming mode(current/pwm/both)
    • ....

    Best Regard

    Monet Xu

  • 0 in reply to Monet Xu
    Prodigy 50 points

    Hi Monet,

    thanks again for your answer! Okay the LP5036 is not suited for this application.

    I want to drive 3 LEDs (2.8 - 3.1V each) in series to match my supply voltage of 12V. If possible 20 Channels with a current range of 20 - 30mA would be perfekt.  Dimming mode PWM, if possible both (pwm and current dimming). For control I want to use I2C.

    Regards

    Claudius