Soft start circuit based on feedback voltage clamping soft start signal

Abstract

The invention discloses a soft start circuit based on a feedback voltage clamping soft start signal, and mainly aims to overcome the drawback that soft start protection cannot be provided in the process that output voltage recovers from an abnormal condition in the prior art. The circuit comprises a constant current source I1 and a capacitor Cs, wherein the constant current source I1 charges the capacitor Cs to generate a soft start signal VS which climbs upward with a slope for replacing a reference voltage upon start so as to allow an output voltage to rise smoothly; the output end of the constant current source I1 and the output end of the capacitor Cs are connected with a soft start signal clamping circuit which performs clamping on the soft start signal Vs under the abnormal condition; and the control end A of the clamping circuit is connected with an output voltage monitoring circuit which is used for monitoring the output voltage and controlling the operation condition of the clamping circuit. When the method is used, the condition of the output voltage can be monitored under different conditions such as a condition that the output voltage climbs to a normal value or recovers from the abnormal condition, and the active soft start protection is provided for a voltage regulator circuit and can be used in different voltage regulator circuits.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and relates to an analog integrated circuit, in particular to a soft start circuit based on a feedback voltage clamp soft start signal, which can be used in various power management chips. Background technique [0002] Various voltage stabilizing circuits generally sample the output voltage, and use the error amplifier and reference voltage to feedback and adjust the output voltage value. In the start-up phase of the voltage regulator circuit, since the output voltage is far lower than the set output value, the error amplifier in the feedback loop is in an unbalanced state, and the driving capability of the output stage circuit reaches the limit value, and the output voltage will be increased as soon as possible, resulting in input surges. inrush current. The surge current will not only cause a sudden drop in the voltage of the power line, affect the normal operation of other circuit...

AI Technical Summary

Problems solved by technology

The traditional soft-start circuit can only act passively during the power-on start-up and enable start-up phases. Since it cannot monitor the state of the output voltage, when the voltage regulator circuit recovers from an abnormal state, the traditional soft-start circuit cannot actively function and cannot Eliminate inrush current and output voltage overshoot during recovery, so it cannot provide complete soft-start protection for voltage regulator circuits

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