Switching power supply

Abstract

The invention discloses a switching power supply, which comprises an inductor and a master switch, wherein the master switch is controlled to turn on and turn off, so that the output end of the switching power supply outputs output voltage; the switching power supply further comprises a first branch, a detection module and a logic module, wherein the first branch is connected to the inductor in parallel and comprises a first switch and a ringing suppression resistor which are connected in series, and a connection node of the inductor and the master switch is marked as a switching node; the detection module is suitable for detecting whether associated voltage is smaller than threshold voltage, the output end outputs a detection result, and the associated voltage is associated with the voltage of the switching node; the first input end of the logic module is coupled to the output end of the detection module and the second input end of the logic module is coupled to the control end of the master switch; when the master switch is controlled to turn off and the detection result indicates that the associated voltage is smaller than the threshold voltage, the logic module controls the first switch to turn on until the master switch is controlled to turn on, otherwise the logic module controls the first switch to turn off. According to the scheme of the invention, the ringing can be suppressed, the cost is high and the stability is high.

Description

technical field [0001] The invention relates to the field of power supply design, in particular to a switching power supply. Background technique [0002] Switching power supply is a kind of power supply that uses modern power electronic technology to control the time ratio of switching on and off to maintain a stable output voltage. A switching power converter generally consists of a pulse width modulation (Pulse Width Modulation, PWM for short) control circuit, an energy storage element (such as an inductor) and a switch tube. A large number of switching power supply converters are used in mobile terminals, for various internal modules such as a central processing unit (Central Processing Unit, referred to as CPU), a subscriber identification module (Subscriber Identification Module, referred to as SIM) card, a radio frequency power amplifier, etc., Provide stable power. [0003] figure 1 A switched DC boost switching power supply 100 is shown, and the switching power s...

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Problems solved by technology

[0004] A method of suppressing ringing in the prior art is to insert a magnetic bead L2 between the input terminal of the switching power supply 100 and the inductor L1, but this will increase the system cost; in additi

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