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LM25069-2

Jim Lacey
Prodigy 20 points
Other Parts Discussed in Thread: LM25069, LM5069

Hi ,

I was using an LM5069-2 for soft start/ overcurrent protection. I changed to a LM25069-2 and have a low resistance between pin 4 and 5 about 100R after recycling.

Has anyone any ideas as to what is causing this

Thanks 

 Jim Lacey

 

 

  • 0
    TI__Genius 13485 points

    Hi Jim,

    The first thing that comes to mind is if any abs. max. voltages are exceeded.  The main difference between the two devices is the voltage range, what input voltage are you operating at? 

    It would make more sense if you changed from an LM25069 to an LM5069 in this case, because the abs. max. on the LM5069 UVLO pin is 7V and the abs. max. on the LM25069 UVLO pin is 20V.  What is the voltage of the UVLO pin when VIN comes up?

    Regards,

    Mike

  • 0 in reply to Michael Hartshorne
    Prodigy 20 points

    Hi Mike,

     

    I originally had an LM5069 in the application but ran into problems as the input

    voltage dips to 8.5V during transients when the battery is low. The LM5069 trips out at 8.8V

    A zener diode was used to limit the voltage on the OVLO pin which rated at 7V max. for the LM5069.

    Is the UVLO pin is rated at 100V for the LM5069 and 20V for the LM25069 as per data sheets?

     

    In the application the voltage is 12V with an absolute max. of 18V. The problem however occurs with

    12V input, so the maximum voltage is not exceeded for either device.

     

    For testing the UVLO pin comes up with the input supply. The OVLO pin is tied to 0V via a diode.

     

    Thanks and Regards,

     

      Jim  

    LM5069

    Absolute Maximum Ratings

    VIN to GND (2) -0.3V to 100V

    SENSE, OUT, PGD to GND -0.3V to 100V

    GATE to GND (2) -0.3V to 100V

    UVLO to GND -0.3V to 100V

    OVLO to GND -0.3V to 7V

    VIN to SENSE -0.3V to +0.3V

    LM25609

    Absolute Maximum Ratings

    VIN to GND(4) -0.3V to 20V

    SENSE, OUT, PGD to GND -0.3V to 20V

    UVLO to GND -0.3V to 20V

    OVLO to GND -0.3V to 20V

    VIN to SENSE -0.3V to +0.3V