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LM5005

Ignacio Linares
Expert 1655 points
Other Parts Discussed in Thread: LM5005

I have a customer asking:

  1. Is there a problem applying the 5V on Vout w/o Vin? During the programming of the board we may need to apply external power to the board rather than using high input voltage.
  2. The internal current limit of the part is quite high (3.25 A typical)? Can it be reduced with external components (like Ramp generator)?  (Thoughts behind question #2:  LM5005 is capable of delivering up to 2.5A.  In our design we really don’t need more than 1.5A. Since part current limit is high, it seems we need to oversize inductor and Schottky diode to handle overcurrent conditions (that are below  LM5005 current limit).  Lowering the internal current limit should help.)
  • 0
    TI__Genius 13700 points

    Hello Ignacio,

    1. Looking at the datasheet there should not be a problem having voltage on the output and none on the input. The freewheeling diode will stop conduction. The high-side FET is unpowered and the bootstrapping through the PRE should not occur with out an input voltage.

    2. You are looking to set a lower current limit for the application than what is inherent in the LM5005 and you are concerned about over-currenting the connected project? It looks like you could adjust the value of R-ramp and C-ramp to trick the chip into thinking the current is higher than it is thereby shifting the current limit lower. This is just a speculation though.

     

    Ryan May

  • 0 in reply to Ryan May
    TI__Genius 13700 points

    Hello Ignacio,

     

    I wanted to check to see if this issue is resolved or if there are any lingering issues that I help work out.

     

    Ryan May