• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 1460 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM3435: LED Current and inductor value setteing

Atsushi Yamauchi
Genius 4810 points

Part Number: LM3435

I would like to confirm the setting of LED current and inductor value.

For LED current min 50mA, we need to set LED current 500mA by the resister IREFx and LED current register for 50mA?

Is this correct?

If it is correct, I have a question of inductor value.

In this case, is ILED(min)  for equation (12)  50mA?

And I think the inductor value is limited Iripple(max) - Iripple(min) (it needs 300mA min).

Is this correct?

Best regards,

Atsushi Yamauchi

  • 0
    TI__Mastermind 25500 points

    Hello Atsushi,

    I have contacted the right person to answer your question. But it is the weekend in much of the world so please be patient if it takes a little time. Thanks.

    Regards,

    Clint

  • 0
    TI__Expert 3950 points
    Hi Yamauchi-san,

    I will suggest to set nominal LED current at 500 mA as the minimum full current level we tested with this device is 500 mA.
    If you need lower output current, you can try reducing it through I2C register.

    We did not tested any setup with peak-to-peak inductor ripple current being less than 300 mA.

    If your customer wants to try, s/he may try to maintain CCM with 100 mA peak-to-peak ripple inductor current. By doing so, increasing the capacitors CR, CG and CB might help. NOTE: THIS IS NOT TESTED AND WE DO NOT ASSURE IF IT STILL WORKS PROPERLY.

    Thank you very much!
  • 0 in reply to Issac Hsu
    Genius 4810 points

    Dear Issac-san,

    Thank you for your advise.

    I have a question.

    The customer set the current 50mA to 400mA.

    In this case, can they use inductance ripple current over 300mAp-p?

    I understood they should set the register for lower current and the operation mode will be DCM for setting the lower current by the register.

    If they can use over 300mAp-p ripple current for 50mA to 400mA with setting the register, I will estimate the inductance value.

    Best regards,

    Atsushi Yamauchi 

  • 0 in reply to Atsushi Yamauchi
    TI__Expert 3950 points
    Hi Yamauchi-san,

    I think you could try using 300 mA p-p for your setup.
    I found a measurement record from the ex-HKDC that has measured I2C code 0001 < 0.1 mA while the full current is at 1.5 A level.

    Thanks!
  • 0 in reply to Issac Hsu
    Genius 4810 points
    Dear Issac-san,

    Thank you for your reply.
    I will set the indactor value for 300mA p-p.

    Best regards,
    Atsushi Yamauchi