• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 1242 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LM5008: Lm5008 Short Circuit test failure

Ali Saghafi
Prodigy 110 points
Part Number: LM5008

Hello My friends . 

Im working on a project using lm5008 to produce 12 volts . My input voltage varies between 16 to 60 volts. The IC internal current limit works good and disconnect the circuit in overload and short circuit When the input voltage is low (16 to 36), but when I increase the input voltage ,  and increase the load in high voltage , The IC breaks and burns. 

When I increase the load step by step when the input voltage is 60 volts , suddenly the output voltage rises and then the IC breaks, 

This is my circuit : 

This picture is the sw pin and output when the load is 40 Ohms (300 mA)

And this is the sw pin and output  when the load is 20 Ohms (600 mA)[I expected the circuit be off in this current].

Please Help me.

  • 0
    TI__Mastermind 40060 points
    Hello Ali,

    The reason why the device fails is likely due to the VCC abs max (14V) being violated. the output should regulate under all conditions.

    There are a couple of things I would check.

    1. Please follow the guidelines given in the datasheet relating to the ripple voltage required at the Feedback node. This should be set to 25 to 50mV using a series resistor at Cout.
    2. Please check the ISAT rating of your inductor under overload conditions. You should make sure that the ISAT>0.61A.

    If you need more guidance for ripple generation at the feedback node in COT regulators please see app note below.


    David.

    www.ti.com/.../snva776a.pdf