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LM3402HV: Is it better to attach any capacitor between LED anode and cathode to avoid flicker?

Kazuya Nakai59
Guru 20640 points
Part Number: LM3402HV
Other Parts Discussed in Thread: TPS922052

Hello guys,

One of my customers is considering using LM3402HV for their new products.

At this moment, they have the following questions.
Could you please give me your reply?

Q1.
They are going to set fSW to about 500kHz.
They worry about flicker. Can any flicker be not observed because 500kHz fSW is high frequency against human eyes?
Or is it better to attach any capacitor between LED anode and cathode to avoid flicker?

Q2. 
They want to apply about 1.2kHz PWM signal to DIM terminal for LED brightness control.
Is this 1.2kHz no problem for LM3402HV?
Or is it too high frequency?

Your reply would be much appreciated.

Best regards,
Kazuya. 

  • 0
    TI__Genius 17745 points

    Hi Kazuya,

    A1. The 500kHz switching frequency is too high for human eye to detect. No flicker will be observed if the external components are selected appropriately.

    A2. It is possible for LM3402HV to achieve 1.2kHz PWM dimming if the external components are selected appropriately.

    I would recommend customer switch to our newer device TPS922052/3/4/5 for its better capability of doing high-frequency PWM dimming.

    Best Regards,

    Steven

  • 0 in reply to Steven Li
    Guru 20640 points

    Hi Steven,

    Thank you very much for your reply.

    The reply is very helpful for the customer and me.

    Thank you again and best regards,
    Kazuya.

  • 0 in reply to Kazuya Nakai59
    TI__Genius 17745 points

    Hi Kazuya,

    You are welcome. I am going to close this thread. Please feel free to contact me again if you have any further question.

    Best Regards,

    Steven