A soft start circuit with digital logic multiplexing control

Abstract

A soft start circuit with digital logic multiplexing control belongs to the technical field of analog integrated circuits. It includes a soft start charging module, a comparison module and a logic control module. When the switching power supply is working normally, the soft start charging module is used to charge the soft start capacitor. When overloaded, the counter in the control logic control module starts counting from zero, and soft starts when it counts to n. The circuit enters the hiccup mode. In the hiccup mode, the two comparison signals generated by the comparison module are used to control the charging and discharging signals, thereby controlling the charging or discharging of the soft-start capacitor. The soft-start circuit exits the hiccup mode when the discharge counter decreases by one bit until it reaches zero. , making the switching power supply resume normal operation. The invention can make the soft start in the overcurrent state incomplete discharge, thereby reducing the delay when powering on again; and using the digital multiplexing technology, on the premise of reducing the system complexity and power consumption, the soft start process can be realized. Precise control.

Description

technical field [0001] The invention belongs to the technical field of analog integrated circuits, and in particular relates to a soft start design for overcurrent protection with digital logic control. Background technique [0002] The soft-start circuit of the switching power supply controls the maximum power in the starting phase of the power supply to avoid the adverse effects caused by the surge current, and the power-on time of the soft-start circuit directly affects the performance index of the switching power supply. For power applications, the shorter the starting time is expected The better, the more efficient the circuit. The traditional soft-start circuit quickly discharges the soft-start capacitor to the ground potential after an error working state such as overcurrent occurs, until the working state returns to normal and starts again. However, high-speed circuits often require a faster turn-on time, so traditional soft-start circuits cannot be powered on again...

AI Technical Summary

Problems solved by technology

[0003] Aiming at the shortcomings of the above-mentioned traditional soft-start circuit that cannot be powered on quickly after over-current discharge, the present invention proposes a soft-start circuit, so that the soft-start will not be locked in the discharge state under the condition of over-current, but uses digital logic to Make the soft-start circuit enter the hiccup mode, prepare for re-charging at any time, and reduce the delay of power-on again; in addition, the soft-start control of the system adopts multiplexing technology, which reduces system complexity and power consumption

Images