Sg Micro Corp.

Lidi Zhang

Disclosed is a low dropout linear voltage regulator and a control circuit thereof. The control circuit includes an error amplifier and a backflow prevention circuit, which compares an input voltage with an output voltage, to switch a substrate voltage and a voltage at a control terminal of the power transistor to a higher one of the input voltage and the output voltage, thus the power transistor and its parasitic diode can be turned off in time when the output voltage is greater than the input voltage, so as to prevent the power transistor from being damaged by current backflow and improve reliability of the low dropout linear regulator.

Low dropout linear regulator and control circuit thereof

A one-shot circuit is provided. The one-shot circuit includes a one-shot main circuit and a shielding time window circuit. The one-shot main circuit is configured to receive, through a NOR gate, an input signal of the one-shot circuit, the feedback of an output signal of the one-shot circuit, and a time window signal output by the shielding time window circuit, and then obtain the output signal through a first RC delay circuit and a logic gate. The time window signal is a signal that resists the interference of the abnormal pulse of the input signal with the output signal. The shielding time window circuit is configured to receive the feedback of the output signal, and then obtain the time window signal through a second RC delay circuit and a logic gate.

One-shot circuit

Disclosed is a low dropout linear voltage regulator and a control circuit thereof. The control circuit comprises an error amplifier, a foldback current-limiting protection circuit, an undershoot suppression circuit and an output detection circuit. The foldback current-limiting protection circuit limits the output current of power transistor and performs short circuit protection, the undershoot suppression circuit pulls the control terminal of the power transistor to low voltage level when the output voltage undershoots. The output detection circuit judges whether the output voltage rises to a preset voltage value in the startup stage, and before the output voltage rises to the preset voltage value, disables the undershoot suppression circuit and the foldback characteristic of the foldback current-limiting protection circuit, which can prevent normal startup of the circuit from being affected by a maloperation of the foldback current-limiting protection circuit and the undershoot suppression circuit during the startup process, improve on-load startup ability.

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Beijing, China

Lidi Zhang