Switching power supply with constant on-time control, and control circuit and control method for switching power supply

Abstract

The invention discloses a switching power supply with constant on-time control, and a control circuit and a control method for the switching power supply. When the switching power supply enters a superaudio mode, a low-side switch tube is switched on to discharge an output capacitor, a complementary ramp compensation signal of which the voltage is raised from initial voltage is generated in the discharge stage, the algebraic sum of the complementary ramp compensation signal and reference voltage is compared with a feedback signal representing output voltage, the discharge time of the low-side switch tube is shortened, the switch-on of a high-side switch tube is accelerated, audio noise is avoided, and dipulse in the superaudio mode is eliminated, so that the output voltage ripple of the switching power supply is reduced, the loss of the high-side switch tube is reduced, and the efficiency of the switching power supply is improved.

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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