CN-224231942-U - Short circuit detection circuit of switching tube, switching converter and chip

CN224231942UCN 224231942 UCN224231942 UCN 224231942UCN-224231942-U

Abstract

The application discloses a short circuit detection circuit of a switching tube, a switching converter and a chip, wherein before the circuit is started or enters into formal work from a stop state, a lower switching tube is led to be turned on for a preset time period and then turned off, and detecting the frequency of the voltage signal of the common node of the upper bridge type switching tube and the lower bridge type switching tube at the turn-off moment, and judging that the common node of the upper bridge type switching tube and the lower bridge type switching tube is short-circuited when the detected frequency is larger than a frequency threshold value. The short circuit detection method of the switching tube is simple and reliable, can accurately judge whether the switching node is short-circuited, does not need to conduct the upper switching tube, and does not have failure risk.

Inventors

Wang siyun
XU AIMIN

Assignees

杰华特微电子股份有限公司

Dates

Publication Date: 20260512
Application Date: 20250424

Claims (9)

1. A short circuit detection circuit of a switching tube is applied to a circuit system of a bridge switching tube and is characterized by comprising a switching control circuit and a short circuit judging circuit, The bridge type switching tube comprises an upper switching tube and a lower switching tube, one end of the upper switching tube is connected with a high potential end, one end of the lower switching tube is connected with a low potential end, Before the circuit system enters into formal work from a stop state, the switch control circuit controls the lower switch tube to be conducted for a preset time period and then turns off the lower switch tube, And the short circuit judging circuit detects the frequency of the voltage signal of the common node of the bridge type switching tube at the turn-off moment of the lower switching tube, and judges that the common node of the bridge type switching tube is short-circuited when the detected frequency is larger than a frequency threshold value.
2. The short-circuit detection circuit according to claim 1, wherein the duration of the preset time period is set to any value between 50ns and 150 ns.
3. The short circuit detection circuit of claim 1, wherein the circuitry comprises an inductance connected between the common node of the bridge switching tube and an output of the circuitry, When the common node of the bridge type switching tube is not short-circuited, the parasitic capacitance of the lower switching tube and the inductor are in resonance, and the resonance frequency is recorded as a first frequency; when the common node of the bridge type switching tube is short-circuited, the parasitic capacitance of the lower switching tube and the short-circuited inductance are in resonance, and the resonance frequency is recorded as a second frequency; Wherein the first frequency is less than the second frequency.
4. The short circuit detection circuit according to claim 1, wherein the short circuit judging circuit includes a frequency detecting circuit and a frequency comparing circuit, The frequency detection circuit is used for detecting the frequency of the voltage signal of the common node of the bridge switch tube so as to obtain a frequency detection result, And the frequency comparison circuit compares the frequency detection result with a preset frequency threshold value to judge that the common node of the bridge switching tube is short-circuited according to the comparison result.
5. The short circuit detection circuit of claim 1, wherein entering formal operation from a stopped state comprises the circuitry powering on a started state or entering a restarted state from a failed state.
6. A chip, characterized by comprising a bridge switch tube and the short circuit detection circuit according to any one of claims 1-5, The bridge switching tube and the short circuit detection circuit are integrated in one chip, or one switching tube of the bridge switching tube and the short circuit detection circuit are integrated in one chip.
7. A switching converter comprising a bridge switching tube and a short-circuit detection circuit according to any one of claims 1 to 5, The switch control circuit controls the switching action of the bridge type switching tube to convert input power into output power; The short circuit detection circuit is used for detecting whether the middle node of the bridge type switching tube is short-circuited, and the switch control circuit controls the upper switching tube of the bridge type switching tube not to be conducted under the condition that the short circuit occurs.
8. The switching converter of claim 7, wherein the switching converter is a Buck switching converter.
9. The switching converter of claim 7, wherein the switching converter is a multiphase buck switching converter.

Description

Short circuit detection circuit of switching tube, switching converter and chip Technical Field The present utility model relates to the field of power electronics, and more particularly, to a short circuit detection circuit for a switching tube, a switching converter, and a chip. Background In a switching circuit, an upper bridge type switching tube and a lower bridge type switching tube are commonly connected together to serve as a switching device, as shown in fig. 1, the bridge type switching tube comprises an upper switching tube Q1 and a lower switching tube Q2, the upper switching tube is connected with a high potential end such as an input voltage end Vin, the lower switching tube is connected with a low potential end such as a ground end GND, and the input power is converted into the output power through on-off control of the two bridge type switching tubes. In the process of the operation of the upper switching tube and the lower switching tube of the bridge type switching tube, if the lower switching tube is short-circuited or the line from the node SW of the two switching tubes to the ground is short-circuited before the upper switching tube is turned on, a large instantaneous current is generated if the upper switching tube is turned on, and the switching tube is overheated and damaged. In the prior art, whether a short circuit occurs or not is judged by detecting the voltage of the SW at the moment of switching on the switching tube, but if the short circuit condition is serious, the switching tube is easy to fail. Disclosure of utility model Therefore, the utility model aims to provide a short circuit detection circuit of a switching tube, a switching converter and a chip, which are used for solving the technical problem of inaccurate short circuit detection of the switching tube in the prior art. The short circuit detection circuit of the switch tube is applied to a circuit system of a bridge switch tube and comprises a switch control circuit and a short circuit judgment circuit, wherein the bridge switch tube comprises an upper switch tube and a lower switch tube, one end of the upper switch tube is connected with a high potential end, one end of the lower switch tube is connected with a low potential end, the switch control circuit controls the lower switch tube to be conducted for a preset time period before the circuit system enters a formal work from a stop state, the lower switch tube is turned off, the short circuit judgment circuit detects the frequency of a voltage signal of a public node of the bridge switch tube at the turn-off moment of the lower switch tube, and when the detected frequency is larger than a frequency threshold, the public node of the bridge switch tube is judged to be short-circuited. Preferably, the duration of the preset time period is set to any value between 50ns and 150 ns. Preferably, the circuit system comprises an inductor, the inductor is connected between a common node of the bridge switching tube and an output end of the circuit system, when the common node of the bridge switching tube is not in short circuit, parasitic capacitance of the lower switching tube resonates with the inductor, the resonance frequency is recorded as a first frequency, when the common node of the bridge switching tube is in short circuit, the parasitic capacitance of the lower switching tube resonates with the short circuit inductor, the resonance frequency is recorded as a second frequency, and the first frequency is smaller than the second frequency. Preferably, the short circuit judging circuit includes a frequency detecting circuit for detecting a frequency of a voltage signal of the common node of the bridge switching tube to obtain a frequency detection result, and a frequency comparing circuit for comparing the frequency detection result with a preset frequency threshold to judge that the common node of the bridge switching tube is short-circuited according to the comparison result. Preferably, entering formal operation from a stopped state includes the circuitry powering up the start-up state or entering a restarted state from a failed state. In a second aspect, a chip is provided, including a bridge switch tube and the short circuit detection circuit described above, where the bridge switch tube and the short circuit detection circuit are integrated in a chip, or one of the bridge switch tubes and the short circuit detection circuit are integrated in a chip. The third aspect of the switching converter comprises a bridge type switching tube and the short circuit detection circuit, wherein the switch control circuit controls the switching action of the bridge type switching tube to convert input power into output power, the short circuit detection circuit is used for detecting whether a short circuit occurs at the middle node of the bridge type switching tube, and when the short circuit occurs, the switch control circuit controls the upper switching tube of the bridge t