Power tube overload detection circuit of switching power supply

Abstract

The invention discloses a power tube overload detection circuit of a switching power supply. The overload detection circuit comprises a logic driving circuit, wherein an output end of the logic driving circuit is connected with a control end of a power NMOS (N-channel Metal Oxide Semiconductor) tube; the logic driving circuit comprises a PWM (Pulse-Width Modulation) signal generator, and a first PMOS (P-channel Metal Oxide Semiconductor) tube and a first NMOS tube which are used for directly driving a power NMOS gate electrode and form a phase inverter connection type; drain ends of the first PMOS tube and the first NMOS tube serve as the output end of the logic driving circuit; and the output end of the logic driving circuit is connected with a pull-down branch circuit. With the adoption of the power tube overload detection circuit of the switching power supply, inductive current zero passage and resonance wave trough detection can be achieved by control and detection on a gate electrode signal, multiple peripheral cells are saved, pins of a chip are reduced, and the cost of the chip and a power supply system is lowered greatly.

Description

technical field [0001] The invention belongs to the field of integrated circuits and relates to an overload detection circuit for a switching power supply power tube. Background technique [0002] When the isolated DC / DC converter realizes the electrical isolation between the output and the input, it usually uses a transformer to realize it. Since the transformer has the function of voltage transformation, it is beneficial to expand the output application range of the converter, and it is also convenient to realize multiple outputs of different voltages. , or multiple outputs of the same voltage. [0003] In the switching power supply management chip, according to the different working modes of inductor current and voltage, it can be divided into CCM (continuous current working mode), BCM (critical continuous current working mode), DCM (discontinuous current working mode) and QR ( quasi-resonant control mode), etc. Different power supply system designs will adopt differ...

AI Technical Summary

Problems solved by technology

[0007] Aiming at the existing chips needing to add coupling inductors or auxiliary windings and voltage dividing resistors in order to realize inductance current zero-crossing and resonance valley detection, thus resulting in the disadvantages of increasing system design complexity and cost, the present invention provides a switching power supply power tube overload detection circuit

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