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LM5141: lm5141 in continius current mode (more 512 cycles) wihout hiccup(re-softstart) . It posssble?

Serj jgf
Prodigy 50 points
Part Number: LM5141
Other Parts Discussed in Thread: LM5117

Hi, can lm5141 work  like lm5117 in continius current mode without  hiccup(or re-softstart)?

Lm 5117 uses the RES pin : "The RES pin can also be configured for latch-off mode current limiting or non-hiccup mode cycle-by-cycle current limiting" 

Does LM5141's  RES pin have the same function?

And another question (lm4141) :

What will happen if  in normal operation Vout  increases (+10%) due to connection of an external power source (for example, a battery was connected) ?  The Low Side mosfet will open and will stay open until the Vout is back  to normal (or the mosfet is damaged ), or the bottom mosfet will stay open for one cycle,  or something else? 

Best Regards.      Serj

  

  • 0
    TI__Genius 11040 points
    Hello Serj,

    For the LM5141, by connecting the RES pin to VDD during power up disables hiccup mode protection. Please let me know if you have any additional questions or if this is unclear.

    For your second question, would you be able to help clarify your question? Are you referring to if the battery is connected to the output (Vout)?

    Thank you,

    Katelyn Wiggenhorn
  • 0 in reply to Katelyn Wiggenhorn
    Prodigy 50 points

    Thank you!
    I mean the case of  the battery  "hot" connection to the output when the voltage on the battery is higher than Vout (Vout= 12V, V batt=14V)

  • 0 in reply to Serj jgf
    TI__Genius 11040 points
    Hi Serj,

    What is the input voltage during this case? It is not recommended that Vout is always less than the input voltage.

    If the input voltage is less than the output voltage in this case, then the body diode of the high side FET will conduct. Consequently, the high side FET is at risk to be damaged. To protect against this condition, you can use a schottky diode between Vout and Vin.

    Best Regards,
    Katelyn
  • 0 in reply to Katelyn Wiggenhorn
    Prodigy 50 points

    Good day, Katelyn!

    Vin >Vout  (V in = 25 V, Vout(nominal) = 12V)

    Which controller will work when Vout nominal  icrease (for example, icrease to 14V)? ( Vout nominal determined by feedback resistors)

    Will open the low-side mosfet and will keep it  ALWAYS open until Vout nominal decrease to 12V ?

    Best Regards,  Serj

  • 0 in reply to Serj jgf
    Prodigy 50 points

    Hi, Katelyn.

    For example, for  LTC7800, LTC3891 (Linear Technology, AD) : "An overvoltage comparator guards against transient overshoots as well as other more serious conditions that may overvoltage the output. When the VFB pin rises by more than 10% above its regulation point of 0.800V, the top MOSFET is turned off and the bottom MOSFET is turned on until the overvoltage condition is cleared."

    Best Regards,  Serj

  • 0 in reply to Serj jgf
    TI__Genius 11040 points
    Hello Serj,

    Thank you for clarifying your question further.

    The LM5141 does not have over voltage protection. The LM5141 uses the PGOOD pin to signify when the output voltage exceeds to the nominal range. This can be used in order to trigger protection circuitry.

    Best Regards,
    Katelyn Wiggenhorn
  • 0 in reply to Katelyn Wiggenhorn
    Prodigy 50 points

    Good day, Katelyn!

    Thank you very much !

    Best Regards.  Serj