Functions of LDO

(1)Under voltage lock out (UVLO) 
This function places the IC in the standby state when the input voltage drops below the specified input voltage so that the internal circuit becomes unstable and malfunction does not occur.
(2)Current limit
This function protects against degradation and destruction due to heat generation of the device itself when the output terminal VOUT goes into an unintentional short mode state. There are two types of overcurrent protection: the foldback type that simultaneously reduces the output current and output voltage, and the current limiter type that reduces the output voltage while keeping the output current constant.
(3)Thermal shut down (TSD)
It is a circuit to prevent deterioration and destruction of the device because of remarkable ambient temperature rise, heat generation of the device itself due to unintentional high current load etc. When the specified temperature is detected by the internal temperature detection circuit, the output transistor is turned off.
(4)Output discharge
When the output transistor is turned off, the terminal voltage of VOUT may remain for a certain time depending on the load capacitance connected to the output terminal. This circuit rapidly discharges the charge accumulated on the load side and drops the VOUT terminal voltage to near the IC GND.

LDO block diagram
LDO block diagram

Chapter IV : Local Power Supply ICs

Power Management IC
Example of Power Line Structure in a System
Why POL Supply ICs Are Wanted?
Types of Local Power Supply ICs
Operation of Linear Regulators
Operation of Switching Regulators
Load Switch IC
Functions of Load Switch IC

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