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TLC59116 output current trouble

Mathieu DAVID
Prodigy 10 points
Other Parts Discussed in Thread: TLC59116

     Hello,

I'm an electronic engineer working for an OLED company. I try to develop an electronic card with a TLC59116 because i need to drive and dim 16 different output. 

When I have the adjustment resistor Rext = 1kOhms, it works as the theory:

       - Measured current 20mA

       - When all output are loaded, it still 20mA out.

I have a big issue when change Rext to 195ohms. The supposed output current should be 96mA.

       - When i have only 1 load on one output, the measured current is 94mA as theory.

       - More the number of output loaded is important, more the Imax per output decrease. With all output loaded, Iout = 18mA. It seems to be an overtemperature mode because when I turn on all output the 1st second the current is 90mA and then decrease to 18mA.

This component is supposed to support 120mA to each output, so I'm pretty sure i do something wrong but i cannot find what exactly.

See the schematics in the attached file :  3051.LuckyEye.PDF

Waiting for any help from you, thanks in advance

Mathieu

  • 0
    TI__Expert 5275 points

    Hi Mathieu,

     

    Your REXT calculations are correct.  Also when thermal shutdown happens, it will turn off the channel until it cools down.  Are to seeing 18mA continuously or average?  Are you reading any error flags?

    Also, which package are you using?

     

    I would also recommend you check the OUTx voltage as you turn on more LEDs.  You may be operating in the range I have circled below.  If the output voltage decreases due to larger IR drop, this could limit the maximum output current.

     

     

    Best Regards,

    Adam Hoover

    DLS Applications Team