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LM2596 start time

Patrick Chen
Mastermind 8875 points
Other Parts Discussed in Thread: LM2596, LM2598, LM2597

Hello,

              Do we have start ramp-up rate specification of LM2596 from 0V to 3.6V of input ? Customer hope ramp-rate is over 200us period. Competitor is 

LTC 1763. Thank you.

BR

Patrick

  • 0
    TI__Guru**** 191445 points
    Moving to the Simple Switcher forum...
  • 0
    TI__Expert 4365 points

    Hello,

    I have several questions about your question.

    The LM2596 is a 3A 150kHz non-synchronous buck regulator.

    The LT1763 is 1/2 Amp low noise LDO. (Bipolar P/N prefix LT)

    LTC1763 is not a valid part number (CMOS or BiCMOS prefix LTC)

    Not clear how these can be compared as competition.

    Tell us the actual specifics of the application:

    Vin minimum =

    Vin nominal =

    Vin maximum =

    Vout =

    Iout =

    Load characteristics

    Is Vin already stable and you then actuate the enable input - is that when you want a ramp-up rate figure?

    Or is the enable input grounded and Vin rises and you need to know how long until Vout is in regulation? This may depend on ramp-up rate of Vin.

    Be aware that for 5Vout the input voltage always need to be greater than 8V, so about a 3V overhead needed.

  • 0 in reply to Alan Martin
    Mastermind 8875 points

    Hello Martin 

                please refer to specifics of application. 

    Vin minimum = 5V

    Vin nominal = 5V

    Vin maximum = 5V

    Vout = 3.6V

    Iout = 0.5A

    Enable direct connect to ground and what is ramp up rate ? Thank you.

    BR

    Patrick

  • 0 in reply to Patrick Chen
    Mastermind 8875 points
    Hello Martin,

    Do you have any comments? Thank you.

    BR
    Patrick
  • 0 in reply to Patrick Chen
    TI__Guru 72765 points

    The soft-start for the LM2596 is fixed and not specified.  We can not guarantee that it is longer than 200us

    However, the LM2597 or LM2598 both have adjustable soft-start; one of these may be a better choice.