Over-current protection circuit, DC/DC converter and power management chip

Abstract

The invention relates to an over-current protection circuit, a DC / DC converter and a power management chip. The over-current protection circuit comprises a first power tube, a second power tube, an inductor, a phase inverter, a feedback signal comparator, a controller, a timing control module and a minimum conduction time comparison module; the timing control module is used for outputting a timing signal under the condition that the first power tube is conducted; the minimum on-time comparison module is used for receiving a timing signal and a processing signal output by the phase inverter; the minimum conduction time comparison module acquires the conduction time of the first power tube based on the processing signal, acquires the timing time based on the timing signal, and selects to output a control signal based on the processing signal or the timing signal according to a time comparison result of the conduction time of the first power tube and the timing time; and the control signal is used for indicating the corresponding power tubes to be switched on or switched off. According to the protection circuit, supersaturation of the inductive current can be avoided, and the circuit safety is improved.

Description

technical field [0001] The present application relates to the technical field of power management, in particular to an overcurrent protection circuit, a DC / DC converter and a power management chip. Background technique [0002] DC / DC (Direct current-Direct current converter, direct current to direct current) converters are applied to the power management chip side of electronic products. The converter often only integrates the corresponding power tube and control circuit. The inductor on the converter is charged and discharged during the DC / DC step-up voltage conversion process to improve the conversion efficiency and achieve small loss. Large inductors and capacitors are required outside the chip. , often at the uH (microhenry) level, which will result in higher BOM (Bill of Material, bill of materials) costs, and the extra pins will not be properly utilized, resulting in the limitation of DC / DC conversion circuits in the field of power supply applications. The turn-on tim...

AI Technical Summary

Problems solved by technology

[0002] DC / DC (Direct current-Direct current converter, direct current to direct current) converters are applied to the power management chip side of electronic products. The converter often only integrates the corresponding power tube and control circuit. The inductor on the converter is charged and discharged during the DC / DC step-up voltage conversion process to improve the conversion efficiency and achieve small loss. Large inductors and capacitors are required outside the chip. , often at the uH (microhenry) level, which will result in higher BOM (Bill of Material, bill of materials) costs, and unreasonable use of redundant pins, resulting in limited DC / DC conversion circuits in power supply applications

The turn-on time of the PMOS power tube is determined by the output of the comparator. The traditional voltage comparator has a hysteresis effect. When the inductance value of the inductor is in the uH range, the rising slope of the inductor current is low, and the transmission current of the control path or the comparator The delay has almost no influence on the inductor current, but for the inductance value in the range of nH (nanohenry), the slope of the inductor current is large, and the delay of ns (nanosecond) level will also cause the inductor current to be too large instantaneously. Or in the case of transient changes in the load current, the excessive delay of the control circuit will cause the inductor current to over-current, or even a straight-through situation.

[0003] During the implementation process, the inventors found that there are at least the following problems in the traditional technology: the traditional DC / DC conversion circuit has low safety

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