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TPS60241: Overload protection / current limit characteristics

Mitch Brosnan
Prodigy 20 points
Part Number: TPS60241

I have a design where my output current is very low (10mA range), but upon power up of a circuit connected to the TPS60241 output, there could be a momentary 500mA current, ramping down to 10mA over roughly 100us. 

Can anyone provide the characteristics of the overload protection / current limit? 

  • Is there a time component to the overload protection circuitry?  If so, am I safe with my 500mA for 100us?
  • If it can't source 500mA for 100us, will it shut off? or output 80mA until the current need decreases?
  • Will there be any damage to the device if I use it in this circuit?

Thank you in advance for your help.

Mitch

  • 0
    TI__Mastermind 31255 points

    Hi Mitch,

    Unfortunately, there is not a lot of documentation on the overload protection circuitry on the TPS60241. Usually in a charge-pump, the current limit feature is a current limited switch, which means that the pump switches can only run current up to a certain level, and then be limited at that level. I have ordered an EVM where I can run some tests on the current limit feature of this part and can get back to you on this.

    Thanks,

    Richard

  • 0 in reply to Richard Fu22
    TI__Mastermind 31255 points

    Hi Mitch,

    I have run some tests on the EVM and here are my results.

    I've ran the input at 3.5V and have put it into over current condition using a constant-current setting on an electronic load. The results that I have seen is that in overcurrent conditions, the output voltage will simply fall out of regulation very quickly until the overcurrent condition is removed.

    So to answer your questions:

    1) There is no time-component to overload protection circuitry, the output will simply fall out of regulation until the load condition is removed.

    2) When the part is enabled, being in the current limit condition does not turn enable off.

    3) Based on what you have given me, (I assume a linear ramp down from 500mA to 10mA over 100us) I found that your average current is 255mA, which is 10x higher than the part's current limit. I'm afraid that you will end up damaging the internal switch of the device if you do this. Additionally, your output voltage of the TPS60241 will sag until the 100us is over.

    I think for your condition, it may be better if you utilize a inductor-based power supply to generate the rails you need. This may be a good start:

    http://www.ti.com/tool/PMP20183

    Thanks,

    Richard

    Thanks,

    Richard