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TLC5941 dying

Andrew Stone
Prodigy 70 points
Other Parts Discussed in Thread: TLC59461, TLC5941

Hi, I'm running a chain of TLC chips and I can get the FIRST chip to fail with some kind of internal short from VCC to GND pretty consistently.  If I replace that chip, everything continues to work. 

It seems to me that the only difference between the first chip and the others is that the SIN is coming from the uP.  Are there any conditions where SIN is driven by the TLC?  I am using SPI to drive the chips, so SIN is being used a lot for other SPI communications.  Since the TLC does not have a "chip select" this clocks random data into the TLC all the time, but that does not matter since it is never latched.

How about when the TLC is not powered, etc?

Speaking of which, can the LEDs be powered (i.e. the "OUT" lines) even if the TLC is not powered?  What will happen in this situation.

What is the recommended power sequencing?

TI: Please try to reply ASAP (PM me for why)...

Thanks,

Andrew

  • 0
    TI__Intellectual 980 points

    Hi Andrew-san,

    My name is Narisawa and in charge of LED driver in development group.

    When add high voltage to signal pins before power on, IC is dameged.  

    To  avoid this, ffirst power on in IC and then add high voltage to signal pins next.

    Or add scotkey diode on signal pins like below figure.  

    If  your requiremnt  is under 40mA output current and don't need EEPROM, please try to "TLC59461" device.

    This device is stronger than TLC5941 in this situation.

    Thanks & best Regards

    K.Narisawa