What is a fold-back protection circuit for LDO regulators?

LDO Linear RegulatorsProtection

The Fold-back Protection Circuit shown in the blue ellipse as "Current Limit" protects the LDO regulator from damage by overcurrent if the output pin (VOUT) and the ground pin (GND) are shorted. It consists of the overcurrent protection circuit and the short current protection circuit.

In the typical characteristics, the overcurrent protection activities are shown by the blue line on the "Output Voltage vs. Output Current" graph, and the short current protection activities are shown by the blue circle on the same graph.

The limiting current value of the overcurrent protection is not defined in the datasheet. Please refer to the graph of the typical characteristics. The limiting current value of the short current protection is defined in the datasheet as short current limit (lSC). In Nisshinbo Micro Device' LDO regulators, this is usually set within a range of about 30 mA to 250 mA.

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  Fold-back Protection Circuit

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  Typical Characteristics
  "Output Voltage vs. Output Current"