over current protection in LDO design

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leebluer

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hi, all,

now i am designing the over-current-protection function in LDO. i am confused about the stability of OCP loop, but not the main loop in LDO. why do we need to stable the OCP loop? and i am also puzzled with the function of OCP. is that only to prevent the great current in pass device when Vin is powered on?

thanks
leebluer
 

hi, all,

how to realize the over-current-protection in design? i have used a current-mirror to realize it, but which destroy the stability of LDO loop. i want to know others how to realize it. pls. give me some help

Thanks in advance
leebluer
 

hi, wonbef,

thank you for your reply. but i also cannot get your meaning. could you explain it more detailed?

Thanks
Leebluer
 

The most accurate way would be to use a current mirror (N:1) ratio of power FET to sensor. You can then make the drains of the two transistors equal using an amplifier and generate a "reference gate voltage" on the sensor transistor. Use this voltage to clamp the gate of the power transistor when the current is exceeded.
 

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