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Simple Switcher (LMZ12003) output

Jamie Maxwell
Expert 1530 points
Other Parts Discussed in Thread: LMZ12003

I have an application where the load has a max steady state current of 2A, but an in-rush current of 7.4A for up to 30uS on startup.

Can the output of the Simple switcher withstand this in-rush current?

Is there information on the datasheets or App notes that discuss the output capabilites interms of current/voltage spikes?

thanks

  • 0
    TI__Intellectual 1160 points

    The surge current duration of 30usec is too long for the LMZ12003 to stay out of current limit. The module will limit the output current during this period, resulting in a droop in output voltage. When the load current drops below 3A, operation will return to normal.

    The current limit is cycle-by-cycle, so any load currents in excess of the current limit can only be provided by the output caps. You will have to add a very large amount of output cap to support such a large transient for longer than one cycle. In this case, you will probably need several milli Farads of cap which is impractical and may cause other problems during startup.

    Regards,

    Allan