CN216016438U - Low-power-consumption and low-cost short-circuit protection circuit - Google Patents
Low-power-consumption and low-cost short-circuit protection circuit Download PDFInfo
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- CN216016438U CN216016438U CN202122325183.2U CN202122325183U CN216016438U CN 216016438 U CN216016438 U CN 216016438U CN 202122325183 U CN202122325183 U CN 202122325183U CN 216016438 U CN216016438 U CN 216016438U
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Abstract
The utility model discloses a low-power consumption low-cost short-circuit protection circuit, including signal detection unit, signal drive unit and switch unit: the signal detection unit comprises voltage division resistors R1-R3 and a filter capacitor C1; one end of the R1 is connected with the PWM controller after being connected with the R2 in parallel, and the other end of the R1 is connected with the divider resistor R3, the filter capacitor C1 and the anode of the switch diode D1 respectively; the signal driving unit comprises a D1, a switching triode Q1, a discharging resistor R4 and an energy storage capacitor C2; the anode of the D1 is connected with the signal detection unit, and the other end of the D1 is connected with the base of the Q1; the collector of Q1 is connected with the 7.2V terminal in the PWM controller; the emitter of the Q1 is respectively connected with the discharge resistor R4, the energy storage capacitor C2 and the grid of the Q2 in the switch unit; r4 and C2 are connected in parallel, and the other end of the R4 and the other end of the C2 are connected with an input ground; the switch unit comprises a switch Q2, the grid electrode of the switch Q2 is connected with the signal driving unit, the drain electrode of the switch Q2 is connected with the SS terminal in the PWM controller, and the source electrode of the switch Q8932 is connected with the input ground. The utility model discloses the circuit is simple, low-power consumption, response are fast, the reliability is high.
Description
Technical Field
The utility model relates to a switching power supply technical field, specifically speaking relates to a low-power consumption low-cost short-circuit protection circuit.
Background
The main function of the switching power supply circuit is to realize the conversion of the output voltage by controlling the high-frequency switch of the power device. Because of its advantages of small size, light weight and high power density, it is widely used in various small-sized electronic systems. However, due to the uncertainty and instability of the rear-end load, during the user debugging or testing process, the switching power supply circuit or even the power supply equipment at the front end of the switching power supply often fails due to the problems of abnormal lapping of the rear-end load circuit, short circuit of the load fault and the like. Therefore, a short-circuit protection circuit must be designed inside the switching power supply circuit. On one hand, the power module is protected, and meanwhile, the front-end power supply equipment can be protected from being damaged.
In a switching power supply circuit, the following method is generally used to realize short-circuit protection: the comparator is used as a voltage comparison circuit, reference voltage is set, input current is detected, and when the output end is short-circuited and the input current is abnormal, the comparator outputs high level to turn off the power conversion circuit. The method is common, but has the following disadvantages: 1. a power supply circuit is needed to be designed to supply power to the comparator, and the power consumption of the product is increased. 2. The circuit is more complicated, and the peripheral circuit is many, is unfavorable for cost control and the miniaturized control of product.
Disclosure of Invention
Not enough to prior art exists, the utility model aims to provide a low-power consumption low-cost short-circuit protection circuit to solve the product consumption increase that exists among the prior art and be unfavorable for cost and the problem that the miniaturization required because the circuit is complicated.
In order to solve the technical problem, the utility model discloses a following technical scheme realizes:
the utility model provides a short-circuit protection circuit of low-power consumption low cost, includes signal detection unit, signal drive unit and the switch unit that links to each other in proper order, wherein:
the signal detection unit comprises voltage division resistors R1-R3 and a filter capacitor C1; one end of the voltage division resistor R1 is connected with a COMP terminal in a power conversion circuit PWM controller after being connected with the voltage division resistor R2 in parallel, and the other end of the voltage division resistor R1 is connected with the voltage division resistor R3, the filter capacitor C1 and the anode of a switch diode D1 in a signal driving unit; the voltage dividing resistor R3 and the filter capacitor C1 are connected in parallel, and then the other end of the voltage dividing resistor R3 is connected with an input ground terminal;
the signal driving unit comprises a switching diode D1, a switching triode Q1, a discharging resistor R4 and an energy storage capacitor C2 which are connected; the anode of the switching diode D1 is connected with the signal detection unit, and the other end of the switching diode D1 is connected with the base of the switching triode Q1; the collector of the switching triode Q1 is connected with a 7.2V terminal in the PWM controller of the power conversion circuit; the emitting electrode of the switching triode Q1 is respectively connected with the discharge resistor R4, the energy storage capacitor C2 and the grid electrode of the switching MOSFET Q2 in the switching unit; the other end of the discharging resistor R4 is connected with an input ground terminal after being connected with the energy storage capacitor C2 in parallel;
the switching unit comprises a switching MOSFET Q2; the gate of the switching MOSFET Q2 is connected to the signal driver unit, the drain is connected to the SS terminal of the PWM controller, and the source is connected to the "input ground" terminal.
Furthermore, the resistance values of the voltage dividing resistors R1 and R2 are 10K, the resistance value of the voltage dividing resistor R3 is 2K, and the resistance value of the discharge resistor R4 is 470K.
Furthermore, the capacitance value of the filter capacitor C1 is 0.1uF, and the capacitance value of the energy storage capacitor C2 is 1 uF.
Furthermore, the type of the switching diode D1 is 1N4148 WS-7-F.
Furthermore, the switching triode Q1 is MMBT5551LT 1G.
Further, the switching MOSFET Q2 is 2N 7002.
Compared with the prior art, the utility model, following technological effect has:
(I) the utility model discloses a low-power consumption low-cost short-circuit protection circuit need not independent design supply circuit, and the circuit does not produce the consumption when normally working, only plays effect when short-circuit protection function moves, and the range of application is extensive.
(II) the utility model discloses a low-cost short-circuit protection circuit, it constitutes only needs conventional resistance, electric capacity, diode and triode, and the circuit is simple, with low costs, response speed is fast, and realizes the miniaturization easily.
In summary, in a conventional control mode, a voltage comparator is used as a core device of a short-circuit protection circuit, a detection signal is compared with a reference signal, and the comparator consumes power all the time no matter whether the short-circuit protection circuit is triggered or not, so that the overall power consumption of the switching power supply circuit is increased, and the improvement of the product efficiency is not facilitated. Meanwhile, since there are many peripheral devices, when designing a printed board, the difficulty of layout and wiring is increased, and many devices also increase the cost of products, which is particularly obvious when the products are in batches. Compared with the prior art, the utility model provides a short-circuit protection circuit of low-cost of low-power consumption realizes the short-circuit protection function through resistance-capacitance, two triode class basic devices. The voltage comparator in the conventional scheme is replaced by utilizing the self voltage drop characteristics of the diode and the triode and the switching principle thereof, so that the situation that the power supply circuit of the comparator is designed independently is avoided, and the comparator is simple, low in power consumption, low in cost, fast in response, high in reliability and wide in application range.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention;
the reference numerals in the figures denote: 1. a signal detection unit; 2. a signal driving unit; 3. a switch unit.
Detailed Description
The following embodiments of the present invention are given, and it should be noted that the present invention is not limited to the following embodiments, and all the equivalent transformations made on the basis of the technical solution of the present application all fall into the protection scope of the present invention.
Example 1:
the present invention will be described in further detail with reference to the accompanying drawings.
With reference to fig. 1, the utility model provides a low-power consumption low-cost short-circuit protection circuit, including consecutive signal detection unit 1, signal drive unit 2 and switch unit 3. Wherein:
the signal detection unit 1 is used for dividing and filtering the voltage signal detected by COMP and providing bias voltage for the signal driving unit;
the signal driving unit 2 is used for converting the bias voltage provided by the signal detection unit into a control signal of the switching unit.
The switch unit 3 is used for pulling down the SS terminal in the PWM controller of the power conversion circuit to realize short-circuit protection. The power conversion circuit PWM controller is a core device of a switching power supply circuit.
As a preferable mode of the present embodiment, the signal detection unit 1 includes voltage dividing resistors R1 to R3 and a filter capacitor C1. One end of the voltage dividing resistor R1 is connected with a COMP terminal in the power conversion circuit PWM controller after being connected with the voltage dividing resistor R2 in parallel, and the other end of the voltage dividing resistor R3 is connected with the anode of a switch diode D1 in the signal driving unit and the filter capacitor C1 respectively; the voltage dividing resistor R3 and the filter capacitor C1 are connected in parallel, and then the other end of the voltage dividing resistor R3 is connected with an input ground terminal.
As a preferable mode of the present embodiment, the signal driving unit 2 includes a switching diode D1, a switching transistor Q1, a discharging resistor R4, and an energy storage capacitor C2 connected. The anode of the switching diode D1 is connected with the signal detection unit, and the other end of the switching diode D1 is connected with the base of the switching triode Q1; the collector of the switching triode Q1 is connected with a 7.2V terminal in the PWM controller of the power conversion circuit; an emitter of the switching triode Q1 is respectively connected with the discharge resistor R4, the energy storage capacitor C2 and the gate of a switching MOSFET Q2 in the switching unit; the other end of the discharge resistor R4 is connected with an input ground terminal after being connected with the energy storage capacitor C2 in parallel. In this scheme, when the bias voltage provided by the signal detection unit is greater than V of the switching diode D1 and the switching transistor Q1BEWhen the sum of the conducting voltages is reached, the switching triode Q1 is in saturated conduction, and the 7.2V voltage in the PWM controller charges the energy storage capacitor C2 to about 7V.
As a preference of the present embodiment, the switching unit 3 includes a switching MOSFET Q2. The gate of the switching MOSFET Q2 is connected to the signal driver unit, the drain is connected to the SS terminal in the power converter PWM controller, and the source is connected to the "input ground" terminal. In this scheme, when the gate voltage of Q2 is greater than its turn-on voltage by 2.5V, the switching MOSFET Q2 is turned on, pulling the PWM controller SS low, and the power conversion circuit PWM controller stops operating.
Specifically, the selection of each element in the present embodiment is as follows:
the resistance values of the voltage dividing resistors R1 and R2 are 10K, the resistance value of the voltage dividing resistor R3 is 2K, and the resistance value of the discharge resistor R4 is 470K;
the capacitance value of the filter capacitor C1 is 0.1uF, and the capacitance value of the energy storage capacitor C2 is 1 uF.
The switch diode D1 is 1N4148WS-7-F model.
The switching transistor Q1 is of type MMBT5551LT 1G.
The switching MOSFET Q2 is model 2N 7002.
The working principle of the utility model is as follows:
when the output end of the switching power supply circuit is in no-load, a 7.2V voltage source is output from the PWM controller of the power conversion circuit, and the voltage of a COMP terminal is about 1V. The voltage dividing resistors R1 and R2 in the signal detection unit 1 are connected in parallel and then connected in series with the voltage dividing resistor R3, and then a 0.4V voltage signal is obtained through a C1 filter capacitor. The 0.4V voltage signal is input into the signal driving unit 2, since the conduction voltage of the switching diode D1 is 0.7V, and the conduction voltage of the switching transistor Q1 is 0.7V, the conduction of the switching transistor Q1 requires at least more than 1.4V, therefore, the 0.4V voltage signal is not enough to conduct the switching transistor Q1, the emitter voltage of the switching transistor Q1 is 0V, the switching MOSFET Q1 in the switching unit 3 is not conducted, the SS terminal voltage is about 2.5V, the power conversion circuit PWM controller outputs the driving signal normally, and the switching power supply circuit works normally.
When the output end of the switching power supply circuit is loaded, a 7.2V voltage source is output from the PWM controller of the power conversion circuit, and the voltage of a COMP terminal is about 2.2V. The voltage dividing resistors R1 and R2 in the signal detection unit 1 are connected in parallel and then connected in series with the voltage dividing resistor R3, and then a 0.9V voltage signal is obtained through the C1 filter capacitor. The 0.9V voltage signal is input into the signal driving unit 2, because the conduction voltage of the switching diode D1 is 0.7V, and the conduction voltage of the switching triode Q1 is 0.7V, the conduction of the switching triode Q1 requires at least more than 1.4V, therefore, the 0.9V voltage signal is not enough to conduct the switching triode Q1, the emitter voltage of the switching triode Q1 is 0V, the switching MOSFET Q1 in the switching unit 3 is not conducted, the SS terminal voltage is about 2.5V, the power conversion circuit PWM controller normally outputs the driving signal, and the switching power supply circuit normally works.
When the output end of the switching power supply circuit is short-circuited, a 7.2V voltage source is output from the PWM controller of the power conversion circuit, and the voltage of a COMP terminal rises to be more than 5V at the short-circuit moment. The voltage dividing resistors R1 and R2 in the signal detection unit 1 are connected in parallel and then connected in series with the voltage dividing resistor R3, and then a voltage signal of more than 2V is obtained through a C1 filter capacitor. The 2V voltage signal is input into the signal driving unit 2, the conduction voltage of the switching diode D1 is 0.7V, and the conduction voltage of the switching triode Q1 is 0.7V, so the switching triode Q1 meets the conduction condition and is instantly conducted, the emitter of the switching triode Q1 rapidly charges the energy storage capacitor C2 to about 7V, the grid voltage of the switching MOSFET Q1 in the switching unit 3 is 2.5V greater than the opening threshold of the MOSFET Q1, the SS terminal voltage is pulled down to about 0V, the power conversion circuit PWM controller stops outputting the driving signal, and the switching power supply circuit stops working.
Meanwhile, because the energy storage capacitor C2 and the discharge resistor R4 are connected in parallel, the discharge resistor R4 will slowly discharge the gate voltage of the switching MOSFET Q1 in the switching unit 3, after about 1500ms, when the gate voltage of the switching MOSFET Q1 is discharged to be below 2.5V of the turn-on threshold thereof, the Q1 is turned off, the SS terminal is released, the power conversion circuit PWM controller will recharge the SS terminal to 2.5V, meanwhile, the PWM controller starts to output the driving signal, the switching power supply circuit tries to establish the output voltage, and if the output short circuit abnormality is not released, the above processes are repeated. And when the short circuit abnormality is removed, the output voltage of the switching power supply circuit is normally established.
As can be seen from the above, in the conventional control method, the voltage comparator is used as a core device of the short-circuit protection circuit, and the comparator consumes power all the time no matter whether the short-circuit protection circuit operates, which is not beneficial to improving the product efficiency. In addition, the number of peripheral devices is large, the product cost is increased, the difficulty of layout and wiring is increased, and the reliability is reduced. Compared with the prior art, the utility model provides a short-circuit protection circuit device of low-power consumption low cost is few, with low costs, low power dissipation, response are fast, the reliability is high, and the range of application is extensive.
The above description is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can change or replace the present invention without creative efforts within the technical scope of the present invention.
Claims (6)
1. The short-circuit protection circuit with low power consumption and low cost is characterized by comprising a signal detection unit (1), a signal driving unit (2) and a switch unit (3) which are sequentially connected, wherein:
the signal detection unit (1) comprises voltage division resistors R1-R3 and a filter capacitor C1; one end of the voltage division resistor R1 is connected with a COMP terminal in a power conversion circuit PWM controller after being connected with the voltage division resistor R2 in parallel, and the other end of the voltage division resistor R1 is connected with the voltage division resistor R3, the filter capacitor C1 and the anode of a switch diode D1 in a signal driving unit; the voltage dividing resistor R3 and the filter capacitor C1 are connected in parallel, and then the other end of the voltage dividing resistor R3 is connected with an input ground terminal;
the signal driving unit (2) comprises a switching diode D1, a switching triode Q1, a discharging resistor R4 and an energy storage capacitor C2 which are connected; the anode of the switching diode D1 is connected with the signal detection unit, and the other end of the switching diode D1 is connected with the base of the switching triode Q1; the collector of the switching triode Q1 is connected with a 7.2V terminal in the PWM controller of the power conversion circuit; the emitting electrode of the switching triode Q1 is respectively connected with the discharge resistor R4, the energy storage capacitor C2 and the grid electrode of the switching MOSFET Q2 in the switching unit; the other end of the discharging resistor R4 is connected with an input ground terminal after being connected with the energy storage capacitor C2 in parallel;
the switching unit (3) comprises a switching MOSFET Q2; the gate of the switching MOSFET Q2 is connected to the signal driver unit, the drain is connected to the SS terminal of the PWM controller, and the source is connected to the "input ground" terminal.
2. The short-circuit protection circuit with low power consumption and low cost as claimed in claim 1, wherein the resistances of the voltage dividing resistors R1 and R2 are 10K, the resistance of the voltage dividing resistor R3 is 2K, and the resistance of the discharge resistor R4 is 470K.
3. The short-circuit protection circuit with low power consumption and low cost as claimed in claim 1, wherein the capacitance of the filter capacitor C1 is 0.1uF, and the capacitance of the energy storage capacitor C2 is 1 uF.
4. The low power consumption low cost short circuit protection circuit of claim 1, wherein said switching diode D1 is type 1N4148 WS-7-F.
5. The low power consumption and low cost short circuit protection circuit of claim 1, wherein said switching transistor Q1 is of the type MMBT5551LT 1G.
6. The low power consumption low cost short circuit protection circuit of claim 1, wherein said switching MOSFET Q2 is of type 2N 7002.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122325183.2U CN216016438U (en) | 2021-09-24 | 2021-09-24 | Low-power-consumption and low-cost short-circuit protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122325183.2U CN216016438U (en) | 2021-09-24 | 2021-09-24 | Low-power-consumption and low-cost short-circuit protection circuit |
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| Publication Number | Publication Date |
|---|---|
| CN216016438U true CN216016438U (en) | 2022-03-11 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202122325183.2U Active CN216016438U (en) | 2021-09-24 | 2021-09-24 | Low-power-consumption and low-cost short-circuit protection circuit |
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| CN (1) | CN216016438U (en) |
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- 2021-09-24 CN CN202122325183.2U patent/CN216016438U/en active Active
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