Switching power supply controlled by constant on-time length, its control circuit and control method

Abstract

Disclosed are a switching power supply controlled by a constant conduction period, a control circuit and a control method thereof. When the switching power supply enters the super-audio mode, turn on the low-side switching tube to discharge the output capacitor, and generate a supplementary slope compensation signal whose voltage rises from the initial voltage during the discharge phase, and combine the supplementary slope compensation signal with the The algebra of the reference voltage is compared with the feedback signal representing the output voltage, which shortens the discharge time of the low-side switch and accelerates the conduction of the high-side switch. While avoiding audio noise, it eliminates the dual Pulse, thereby reducing the output voltage ripple of the switching power supply, reducing the loss of the high-side switching tube, and improving the efficiency of the switching power supply.

Description

technical field [0001] Embodiments of the present invention relate to electronic circuits, and in particular to a switching power supply controlled by a constant on-time duration, a control circuit and a control method thereof. Background technique [0002] Constant on-time control has been well applied in the power supply field due to its superior load transient response, simple internal structure and smooth operation mode switching. figure 1 It is a schematic circuit diagram of a conventional switching power supply 100 controlled by a constant on-time duration. The switching power supply 100 includes a conduction duration control unit 101 , a comparison unit 102 , a logic unit 103 , a switch circuit 104 and a slope compensation unit 105 . The switch circuit 104 adopts a synchronous buck conversion topology, including a high-side switch HS, a low-side switch LS, an inductor L, and an output capacitor C, wherein the common terminal of the high-side switch HS and the low-sid...

AI Technical Summary

Problems solved by technology

[0007] Depend on figure 2 It can be seen that in the super-audio mode of the existing switching power supply 100, the high-side control signal HCTRL may have two consecutive conduction pulses in the same cycle, so there will also be double pulses at the switching node SW, which makes the switching power supply output The voltage ripple is large, and the switching loss of the high-side switching tube HS is high, which adversely affects the efficiency of the switching power supply

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