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LT3080 SET Pin Voltage

Dear All,

In LT3080 datasheet, absolute maximum for SET pin Voltage relative to OUT pin is given as ±0.3V. However, In typical applications circuits on "Adding Shutdown" set pin is clamped to output with 1N4148 which has nominal voltage drop of 1V (higher than 0.3V). Is the maximum value given wrong or should we choose a diode with lower voltage drop? Or am I missing sth?

  • Thanks for the post.  The discrete 1N4148 from SET to OUT in the application example you cite - shown in the image below - protects the LT3080 by shunting transient overload current from inside the LT3080 to the external  clamp diode instead.  The discrete 1N4148 is specified because the 1N4148 has a lower VF than the more resistive silicon diode inside the LT3080.  Just follow the application circuit example in this case.   

    LT3080 DS app example_1.png