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LP8556 / short protection

K.Yaita
Guru 29720 points
Other Parts Discussed in Thread: LP8556

Hi Team,

It seems LP8556 has overcurrent protection, however I think there is unavoidable current path (the red arrow) when VOUT or LED string is shorted to GND.


Do you recommend electrical fuse if my customer concerns it?

Best Regards,
Yaita / Japan disty

  • 0
    TI__Expert 4565 points

    Hi Yaita-san,

    LP8556 is detecting internal SW FET current and stops boost SW when it hits overcurrent limit. Due to the structure of asynchronous boost, input current can be still high when boost output is shorted to GND. So, fuse or power line FET on Vin can be used to protect the circuit. The current rating of fuse can be calculated for each apps load condition. PL FET control may be tricky. Overcurrent condition by output short should be detected by control host and the PL FET should be turned off fast enough. A couple of our LED drivers for bigger size display have this PL FET control itself, but LP8556 needs this control externally. The picture below shows PFET on power line to shut off Vin. SD(GD of PFET) can be controlled by host for LP8556 case.

    Hope this helps.