N-channel input pair voltage regulator with soft start and current limitation circuitry
AssigneeSTMicroelectronics (China) Investment Co., Ltd.
InventorsZhenghao Cui, Fei Wang, Ming Jiang
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Abstract
A voltage regulator includes two input pairs of opposite type transistors, p-type and n-type, to provide a soft-start functionality for gradually increasing the voltage regulator's output voltage from zero, or a voltage below the thresholds of the n-type transistors, to an operational voltage. The voltage regulator operates in a soft-start mode during which a variable input voltage signal is ramped up to allow the output voltage to reach the operational voltage, and a normal-operation mode during which the operational voltage is maintained.
Claims4
A method for operating a voltage regulator, comprising:
- generating an output current applied to an output node of the voltage regulator to produce an output voltage;
- generating a soft-start current in response to a difference between a soft-start feedback signal and a variable ramp signal, wherein the soft-start feedback signal is derived from the output voltage;
- passing the soft-start current through a source-drain path of a transistor;
- adjusting a magnitude of the soft-start current passing through a source-drain path of the transistor by generating a control voltage applied to the gate of the transistor, wherein the control voltage is responsive to a difference between a normal operation feedback signal and a reference signal, and where the normal operation feedback signal is derived from the output voltage;
- mirroring the soft-start current received from the source-drain path of the transistor to generate said output current;
- and
- controlling said variable ramp signal to:
- increase in voltage during a soft-start operating mode;
- and
- remain at a fixed voltage during a normal operating mode following said soft-start operating mode.
Dependencies are inferred from the claim text.