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.
Claims9
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 from a supply voltage a first current wherein, in response to an increase in the supply voltage during start-up of the voltage regulator, a magnitude of the first current increases from a starting current level towards an ending current level that is fixed by a limiting current;
- passing the first current through a source-drain path of a transistor;
- adjusting the magnitude of the first current passing through the source-drain path after start-up through application of a control signal to a gate of said transistor, said control signal having a magnitude corresponding to a difference in magnitude between a feedback signal dependent on the output voltage and a reference signal;
- and
- mirroring the first current received from the source-drain path of the transistor to generate said output current.
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 from a supply voltage a first current having a magnitude that increases from a starting current level towards an ending current level during a start-up and is fixed at the ending current level after start-up;
- passing the first current through a source-drain path of a transistor to output a control current;
- mirroring the control current to generate said output current;
- and
- applying a control voltage to a control terminal of said transistor, said control voltage configured to turn on the transistor during start-up and have a magnitude after start-up that is set in response to a difference in magnitude between a feedback signal dependent on the output voltage and a reference signal.
Dependencies are inferred from the claim text.