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LMZM23600V3EVM: LMZM23600V3SILT (voltage dip )

LUIS GUEVARA
Intellectual 620 points
Part Number: LMZM23600V3EVM
Other Parts Discussed in Thread: LMZM23601

Hello TI;

 We will use the LMZM23600V3SILT or te LMZM23601V3SILT, to genereta a 3.3V Voltage Rail.

 These are our main requirements:

  1. The Power Supply PWA shall provide a 3.3VDC +10%/-5% voltage rail with an operating range of 0mA to 200mA continuous current.
  2. The 3.3VDC voltage rail shall not have a voltage dip of more than 20% with an instantaneous output current of 600mA for 100uSec.

Since we will be working under 200mA, we want to use the 500mA version  (LMZM23600V3SILT).

The questions is can the LMZM23600V3SILT  accomplish requirement number 2 above?

Regards;

Luis

  • 0
    TI__Mastermind 47060 points

    Hi Luis,

    What is your input voltage range? I would need to check if you are potentially hitting HIGH side or LOW side current limit specs based on the LMZM23600V3SILT datasheet.

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Intellectual 620 points

    Hello Jimmy;

     I am attaching an image with our worst scenario (BATPOS is the input voltage to the LMZM2360XV3SILT). In this image BATPOS is ~5V and can go as low as 4V for short periods of time.

     The "3.3V" signal is the output of the LMZM23601 EVM, which looks totally stable while working in our application.

     We have some other scenarios when the Input  to the LMZM2360XV3 can go up to 8.5V.

    For this testing we used a LMZM23601V3SILT, but as stated before we want to use the (LMZM23600V3SILT). since are nominal current consumption will never go over 200mA.

    Regards;

    Luis

  • 0 in reply to LUIS GUEVARA
    TI__Mastermind 47060 points

    Hi Luis,

    Are you expecting an instantaneous current of 600mA from a 200mA continuous load current during turn on?

    Your input voltage range is 4V - 8.5V. I calculated the inductor ripple current based on equation 2 from the attached app note assuming 90% efficiency,the ripple current should be 0.298A. At 200mA loading you will not high any peak current limit using the LMZM23600V3.

    1. I expect the LMZM23600V3 should provide the necessary output voltage regulation +10%/-5% voltage rail for 0mA - 200mA without issue.
    2. Figure 46 shows the transient response for 24VIN to 3.3VOUT at full load 500mA with roughly 10mV voltage dip. Your requirement of the voltage dip being less than 20% of 3.3V (which comes out to be 0.6V drop), should not be a problem for the LMZM23600V3.

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Intellectual 620 points

    Hello Jimmy;

     Thanks for your quick and clear answers.

    The 600mA  dip of 100uSec is more likely to happen during turning on or during an unexpected event  like sudden plug-in or a power glitch .

    Regards;

    Luis

  • 0 in reply to LUIS GUEVARA
    TI__Mastermind 47060 points

    Hi Luis,

    Thank you for the clarification.

    I don't think that will be an issue. Even with inductor ripple added onto the 600mA instantaneous current from transient load conditions, this should not trip the high side current limit of the device.

    Regards,

    Jimmy

  • 0 in reply to Jimmy Hua
    Intellectual 620 points

    Ok, thanks Jimmy.

    Another question, just to clarify; If i am not using the PGOOD signal, Can I left it unconnected right?

    Regards;

    Luis

  • 0 in reply to LUIS GUEVARA
    TI__Mastermind 47060 points

    Hi Luis,

    Yes the PGOOD pin is an open drain output and can be left unconnected.

    Regards,

    Jimmy