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what's the function of this type of LDO ckt?

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youda.chen886

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i dont understand the purpose of this special LDO
i just know there's a pmos used to sense current ....
anybody could tell me more?
 

youda.chen886

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It is over-current protection?
but why does the sensed current need to be added to the reference voltage?
 

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It is over-current protection?
Yes!

why does the sensed current need to be added to the reference voltage?
I would compare its voltage to a reference voltage (with some hysteresis) to completely switch down the output voltage.

In order to achieve a fold-back current limiting -- which might be more favorable in terms of thermal power management and application simplification -- one would subtract the current sensor's created voltage over Rs from Vref (as indicated in the image by "or -") -- or add it to Vfb .
 
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