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  • TI Thinks Resolved

TPS61196: Driving two LED strings with different Voltages

Prodigy 140 points

Replies: 5

Views: 75

Part Number: TPS61196

Hello there,

We plan to use part TPS61196 to drive below LEDs:

  • RED string of 28 LEDs with Vf =2V for a total of 56V
  • BLUE string of 28 LEDs with Vf =3.1V for a total of 86.8V

Is this possible with this part ? 

If not, can you help suggest a suitable solution ?

Appreciate your response.

Thank you.

Regards,

Ryan

  • Hi Ryan,

         Since there is a big voltage difference between this two LED strings, I would not recommend just use this way since this will lead to a high thermal issue, I would recommend adding some resistors to match the voltage difference for the Red LED string. That would have better thermal performance.

    BR

    Sean

  • In reply to Sean Zhou:

    Hi Sean,

    Thank you for your advice, I appreciate it.

    Can you help advice appropriate values for the resistors to match this RED LED string voltage difference ?

    Thanks.

    Regards,

    Ryan

  • In reply to Ryan Delfino:

    Hi Ruay,

       Please use the below equation to calculate the resistor:

       R=(Difference voltage between two channels) / (Current for each channel)

    BR

    Sean

  • In reply to Sean Zhou:

    Hi Sean,

    Can you help check if below diagram is correct based from my understanding to your advice?

    Thanks.

    Regards,

    Ryan

  • In reply to Ryan Delfino:

    Hi Ryan,

        Yes, you have got the right circuit, please go on and any further question, please let me know.

    BR

    Sean

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