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TPS61196: high current ripple

Fandy
Expert 2285 points
Part Number: TPS61196
Other Parts Discussed in Thread: TPS61165

Hello,

My customer find too big LED curent ripple using TPS61196, Current test at J6 total 3channel ,Vout also have ripple, and SW frequency seems not setted 200K.

I haven't find inproper in SCH except check COMP pin parameter, do you have some advise?

  • 0
    TI__Mastermind 22745 points

    Hi Fandy,

         You can try to use 47uH or 68uH for little current ripple; and you can try to set higher switching frequency for better current ripple;

         BTW, for 12V vin and 15V vout with 180mA application , you can use our TPS61165, for TPS61196, it is a little overspec;

    regards

    Sean

  • 0 in reply to Sean Zhou
    Expert 2285 points

    Hi Sean,

    have tried 68uH , but seems peak-peak become bigger,

    and frequency seems just 10K, set value should be 200K.

    TPS61165 just one channel, and unified to TPS61196

  • 0 in reply to Fandy
    TI__Mastermind 22745 points

    Hi Fandy,

         Why you need mutli-channel? 

         It is not reasonable that the ripple will become bigger when the inductor become larger.

    Regards

    Sean

  • 0 in reply to Sean Zhou
    Expert 2285 points

    Hi Sean,

    I test it again, Switching frequency seems right, I changed the switching frequency from 200KHz to 380KHz by change resistor from 200K to 105Kohms, the GDRV frequency seems about 380KHz is 357KHz， but it seems work in hiccup mode,hiccup frequency is 10KHz, and I test the ISNS voltage is exceed the 400mV limit, do you think what happening ?

  • 0 in reply to Fandy
    Expert 2285 points

    Hi Sean,

    yeah,its strange that ripple incrased when inductor inrease ~~

    I increas used LED channel from 3channel to 5channel,  the total current crease to 300mA ，and SW frequecy is correct and no hiccup mode/skip frequency and no audible noisy now(the led voltage also increse to 50V because I can only find 50V LED string).  but used 3 channel,60mA/string still have audible noisy and hiccup