CN219145257U - Step-down power supply circuit with short-circuit protection - Google Patents
Step-down power supply circuit with short-circuit protection Download PDFInfo
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- CN219145257U CN219145257U CN202320048258.3U CN202320048258U CN219145257U CN 219145257 U CN219145257 U CN 219145257U CN 202320048258 U CN202320048258 U CN 202320048258U CN 219145257 U CN219145257 U CN 219145257U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
The embodiment of the utility model provides a step-down power supply circuit with short-circuit protection. The step-down power supply circuit with short-circuit protection comprises: the voltage stabilizing diode Z1, the first switching triode Q1, the second switching triode Q2, the third switching triode Q3, the first capacitor C1, the second capacitor C2, the third capacitor C3 and the first resistor R1; the third capacitor C3 is connected between the emitter of the second switching triode Q2 and the emitter of the third switching triode Q3; the positive electrode of the first capacitor C1 is connected with the base electrode of the third switching triode Q3 through the voltage stabilizing diode Z1; an emitter of the third switching triode Q3 is connected with a cathode of the first capacitor C1; an emitter of the second switching triode Q2 is connected with a collector of the third switching triode Q3; the base electrode of the first switching triode Q1 is connected with the collector electrode of the second switching triode Q2. The utility model solves the technical problem that the step-down circuit is invalid due to overheat burnout of the switching tube when the output is in short circuit.
Description
Technical Field
The utility model relates to the technical field of step-down power supply circuits, in particular to a step-down power supply circuit with short-circuit protection.
Background
The common linear step-down circuit uses a switching tube to absorb the redundant voltage. When the output is short-circuited or the output voltage is reduced too much, the switching tube is overheated and burnt out due to absorbing the excess voltage. After the triode is burned, the voltage reducing circuit is disabled, the output voltage is approximately equal to the input voltage, and the subsequent circuit is easy to damage.
Disclosure of Invention
In order to solve the problem that the step-down circuit is invalid due to overheat burnout of a switching tube when an output is in short circuit, the utility model provides a step-down power supply circuit with short circuit protection, which comprises: the voltage stabilizing diode Z1, the first switching triode Q1, the second switching triode Q2, the third switching triode Q3, the first capacitor C1, the second capacitor C2, the third capacitor C3 and the first resistor R1; the first capacitor C1 is connected with the direct current input end in parallel, and the second capacitor C2 is connected with the load output end in parallel; the third capacitor C3 is connected between the emitter of the second switching triode Q2 and the emitter of the third switching triode Q3; the positive electrode of the first capacitor C1 is connected with the base electrode of the third switching triode Q3 through the voltage stabilizing diode Z1; an emitter of the third switching triode Q3 is connected with a cathode of the first capacitor C1; an emitter of the second switching triode Q2 is connected with a collector of the third switching triode Q3; the base electrode of the first switching triode Q1 is connected with the collector electrode of the second switching triode Q2; the first resistor R1 is disposed between the first capacitor C1 and the zener diode Z1, and the first resistor R1 is connected in parallel with the third capacitor C3.
Compared with the prior art, the technical effect that this embodiment can reach is: through setting up zener diode Z1, first switching triode Q1, second switching triode Q2, third switching triode Q3, first electric capacity C1, second electric capacity C2, third electric capacity C3, first resistance R1 in this take short-circuit protection's step-down power supply circuit. And the first capacitor C1 is arranged in parallel with the direct current input end, the second capacitor C2 is connected in parallel with the load output end, the input can be stabilized through the first capacitor C1, and the output voltage is controlled by controlling the voltage of the two ends of the second capacitor C2. The emitter of the second switching triode Q2 is connected with the emitter of the third switching triode Q3 through the third capacitor C3; the positive electrode of the first capacitor C1 is connected with the base electrode of the third switching triode Q3 through the voltage stabilizing diode Z1; an emitter of the third switching triode Q3 is connected with a cathode of the first capacitor C1; an emitter of the second switching triode Q2 is connected with a collector of the third switching triode Q3; the base electrode of the first switching triode Q1 is connected with the collector electrode of the second switching triode Q2; the first resistor R1 is arranged between the first capacitor C1 and the zener diode Z1, the first resistor R1 is connected with the third capacitor C3 in parallel, the zener diode Z1 can be limited by the first resistor R1, and the third capacitor C3 is charged by the first resistor R1; when the output end of the load is short-circuited or the output voltage is reduced too much, the zener diode Z1 is not conducted any more, so that the third switching triode Q3, the second switching triode Q2 and the first switching triode Q1 are not conducted any more, at the moment, the first resistor R1 charges the third capacitor C3, so that the zener diode Z1 is conducted again, and the cycle is repeated until the fault disappears and normal operation is restored.
In one embodiment of the present utility model, the step-down power supply circuit with short-circuit protection further includes: and a second resistor R2, wherein the second resistor R2 is connected between the collector electrode of the third switching triode Q3 and the base electrode of the second switching triode Q2.
Compared with the prior art, the technical effect that this embodiment can reach is: through set up second resistance R2 between third switch triode Q3's collecting electrode and second switch triode Q2's base, can utilize second resistance R2's current-limiting effect protection second switch triode Q2 and third switch triode Q3, prevent second switch triode Q2's base electric current too big, the circuit appearance short circuit.
In one embodiment of the present utility model, the step-down power supply circuit with short-circuit protection further includes: the diode D1 is connected to the first capacitor C1 and the second capacitor C2.
Compared with the prior art, the technical effect that this embodiment can reach is: through setting up diode D1 intercommunication first electric capacity C1 and second electric capacity C2, can improve the discharge rate of second electric capacity C2 through diode D1 for the discharge rate of the parallelly connected load output of direct current input of first electric capacity C1 and second electric capacity C2 keeps synchronous.
In one embodiment of the present utility model, when the load output end works normally, the zener diode Z1, the third switching transistor Q3, the second switching transistor Q2, and the first switching transistor Q1 are turned on in sequence, and a first loop, a second loop, and a third loop are formed, so that the voltage across the second capacitor C2, the base voltage of the first switching transistor Q1, and the emitter voltage of the first switching transistor Q1 are clamped by the zener diode Z1.
Compared with the prior art, the technical effect that this embodiment can reach is: when the load output end works normally, a first loop, a second loop and a third loop can be formed by sequentially conducting the voltage stabilizing diode Z1, the third switching triode Q3, the second switching triode Q2 and the first switching triode Q1, so that the voltage of two ends of the second capacitor C2, the base voltage of the first switching triode Q1 and the emitter voltage of the first switching triode Q1 can be clamped through the voltage stabilizing diode Z1, the voltage of two ends of the second capacitor C2, the base voltage of the first switching triode Q1 and the emitter voltage of the first switching triode Q1 are approximately equal to the conducting voltage of the voltage stabilizing diode Z1, and the working stability of a circuit can be improved.
In one embodiment of the present utility model, when the load output end works normally, the voltage across the third capacitor C3 is greater than the voltage across the zener diode Z1, and the zener diode Z1 and the third switching triode Q3 are conducted to form a first loop, so that the voltage across the second capacitor C2 is clamped by the zener diode Z1.
Compared with the prior art, the technical effect that this embodiment can reach is: when the load output end works normally, the voltage at two ends of the third capacitor C3 is larger than the voltage at two ends of the zener diode Z1, and the zener diode Z1 and the third switching triode Q3 are conducted to form a first loop. The current flows from the first capacitor C1, sequentially passes through the first resistor R1, the zener diode Z1, the base electrode of the third switching triode Q3, the emitter electrode of the third switching triode Q3 and returns to the first capacitor C1. At this time, the voltage across the second capacitor C2 is clamped by the zener diode Z1, which is approximately equal to the on voltage of the zener diode Z1.
In one embodiment of the present utility model, after the zener diode Z1 is turned on with the third switching transistor Q3, the second switching transistor Q2 is turned on to form the second loop, so that the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1.
Compared with the prior art, the technical effect that this embodiment can reach is: after the zener diode Z1 is turned on with the third switching transistor Q3, the second switching transistor Q2 is turned on to form a second loop. The current flows out from the third capacitor C3, flows through the emitter of the second switching triode Q2, the second resistor R2, the collector of the third switching triode Q3, the emitter of the third switching triode Q3 in sequence, and returns to the third capacitor C3. At this time, the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1, which is approximately equal to the turn-on voltage of the zener diode Z1.
In one embodiment of the present utility model, when the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1, the emitter voltage of the first switching transistor Q1 is clamped by the zener diode Z1, forming the third loop.
Compared with the prior art, the technical effect that this embodiment can reach is: when the base voltage of the first switching triode Q1 is clamped by the zener diode Z1, the emitter voltage of the first switching triode Q1 follows the base voltage of the first switching triode Q1 and is approximately equal to the turn-on voltage of the zener diode Z1, forming a third loop. The current flows out from the first capacitor C1, flows through the collector of the first switching triode Q1, the emitter of the first switching triode Q1, and the second capacitor C2 in sequence, and returns to the first capacitor C1.
In one embodiment of the present utility model, when a short circuit fault occurs at the load output terminal or the output voltage of the load output terminal decreases abnormally, the voltage across the third capacitor C3 is smaller than the zener diode Z1, and the zener diode Z1 and the third switching transistor Q3 are not turned on any more.
Compared with the prior art, the technical effect that this embodiment can reach is: when a short circuit fault occurs at the load output end or the output voltage of the load output end is reduced abnormally, the load output end is at zero potential or low potential, at the moment, the emitter frequency of the third switching triode Q3 is zero, the base voltage of the first switching triode Q1 is reduced, the third switching triode Q3 cannot be conducted, and the zener diode Z1 cannot be conducted.
In one embodiment of the present utility model, when the zener diode Z1 and the third switching transistor Q3 are no longer conductive, the second switching transistor Q2 and the first switching transistor Q1 are no longer conductive.
Compared with the prior art, the technical effect that this embodiment can reach is: when the zener diode Z1 and the third switching transistor Q3 are not turned on, the collector voltage of the second switching transistor Q2 is smaller than the emitter voltage of the third switching transistor Q3, the second switching transistor Q2 is not turned on, and the first switching transistor Q1 is not turned on.
In one embodiment of the present utility model, when the second switching transistor Q2 and the first switching transistor Q1 are not turned on any more, the first resistor R1 charges the third capacitor C3, so that the zener diode Z1 is turned on to clamp the voltage across the second capacitor C2.
Compared with the prior art, the technical effect that this embodiment can reach is: when the second switching triode Q2 and the first switching triode Q1 are not conducted any more, the first resistor R1 charges the third capacitor C3 again to enable the zener diode Z1 to be conducted, and the operation is repeated until the fault disappears.
In summary, the foregoing embodiments of the present application may have one or more of the following advantages or benefits:
(1) Through setting up zener diode Z1, first switching triode Q1, second switching triode Q2, third switching triode Q3, first electric capacity C1, second electric capacity C2, third electric capacity C3, first resistance R1 in this take short-circuit protection's step-down power supply circuit. And the first capacitor C1 is arranged in parallel with the direct current input end, the second capacitor C2 is connected in parallel with the load output end, the input can be stabilized through the first capacitor C1, and the output voltage is controlled by controlling the voltage of the two ends of the second capacitor C2. The emitter of the second switching triode Q2 is connected with the emitter of the third switching triode Q3 through the third capacitor C3; the positive electrode of the first capacitor C1 is connected with the base electrode of the third switching triode Q3 through the voltage stabilizing diode Z1; an emitter of the third switching triode Q3 is connected with a cathode of the first capacitor C1; an emitter of the second switching triode Q2 is connected with a collector of the third switching triode Q3; the base electrode of the first switching triode Q1 is connected with the collector electrode of the second switching triode Q2; the first resistor R1 is arranged between the first capacitor C1 and the zener diode Z1, the first resistor R1 is connected with the third capacitor C3 in parallel, the zener diode Z1 can be limited by the first resistor R1, and the third capacitor C3 is charged by the first resistor R1; when the output end of the load is short-circuited or the output voltage is reduced too much, the zener diode Z1 is not conducted any more, so that the third switching triode Q3, the second switching triode Q2 and the first switching triode Q1 are not conducted any more, at the moment, the first resistor R1 charges the third capacitor C3, so that the zener diode Z1 is conducted again, and the cycle is repeated until the fault disappears and normal operation is restored.
(2) When the load output end works normally, a first loop, a second loop and a third loop can be formed by sequentially conducting the voltage stabilizing diode Z1, the third switching triode Q3, the second switching triode Q2 and the first switching triode Q1, so that the voltage of two ends of the second capacitor C2, the base voltage of the first switching triode Q1 and the emitter voltage of the first switching triode Q1 can be clamped through the voltage stabilizing diode Z1, the voltage of two ends of the second capacitor C2, the base voltage of the first switching triode Q1 and the emitter voltage of the first switching triode Q1 are approximately equal to the conducting voltage of the voltage stabilizing diode Z1, and the working stability of a circuit can be improved.
(2) By adding a short-circuit protection function to the step-down power supply circuit structure, the reliability of the step-down power supply circuit can be improved. In addition, the step-down power supply circuit with the short-circuit protection is simple in structural design, low in cost, obvious in effect and wide in application range, and an additional control circuit is not needed.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a circuit configuration diagram of a step-down power supply circuit with short-circuit protection according to an embodiment of the present utility model.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
Referring to fig. 1, a circuit structure diagram of a step-down power supply circuit with short-circuit protection according to an embodiment of the present utility model is shown. The step-down power supply circuit with short-circuit protection comprises: the voltage stabilizing diode Z1, the first switching triode Q1, the second switching triode Q2, the third switching triode Q3, the first capacitor C1, the second capacitor C2, the third capacitor C3 and the first resistor R1; the first capacitor C1 is connected with the direct current input end in parallel, and the second capacitor C2 is connected with the load output end in parallel; the third capacitor C3 is connected between the emitter of the second switching triode Q2 and the emitter of the third switching triode Q3; the positive electrode of the first capacitor C1 is connected with the base electrode of the third switching triode Q3 through the voltage stabilizing diode Z1; an emitter of the third switching triode Q3 is connected with a cathode of the first capacitor C1; an emitter of the second switching triode Q2 is connected with a collector of the third switching triode Q3; the base electrode of the first switching triode Q1 is connected with the collector electrode of the second switching triode Q2; the first resistor R1 is disposed between the first capacitor C1 and the zener diode Z1, and the first resistor R1 is connected in parallel with the third capacitor C3.
Through setting up zener diode Z1, first switching triode Q1, second switching triode Q2, third switching triode Q3, first electric capacity C1, second electric capacity C2, third electric capacity C3, first resistance R1 in this take short-circuit protection's step-down power supply circuit. And the first capacitor C1 is arranged in parallel with the direct current input end, the second capacitor C2 is connected in parallel with the load output end, the input can be stabilized through the first capacitor C1, and the output voltage is controlled by controlling the voltage of the two ends of the second capacitor C2. The emitter of the second switching triode Q2 is connected with the emitter of the third switching triode Q3 through the third capacitor C3; the positive electrode of the first capacitor C1 is connected with the base electrode of the third switching triode Q3 through the voltage stabilizing diode Z1; an emitter of the third switching triode Q3 is connected with a cathode of the first capacitor C1; an emitter of the second switching triode Q2 is connected with a collector of the third switching triode Q3; the base electrode of the first switching triode Q1 is connected with the collector electrode of the second switching triode Q2; the first resistor R1 is arranged between the first capacitor C1 and the zener diode Z1, the first resistor R1 is connected with the third capacitor C3 in parallel, the zener diode Z1 can be limited by the first resistor R1, and the third capacitor C3 is charged by the first resistor R1; when the output end of the load is short-circuited or the output voltage is reduced too much, the zener diode Z1 is not conducted any more, so that the third switching triode Q3, the second switching triode Q2 and the first switching triode Q1 are not conducted any more, at the moment, the first resistor R1 charges the third capacitor C3, so that the zener diode Z1 is conducted again, and the cycle is repeated until the fault disappears and normal operation is restored.
For example, the zener diode Z1 and the third switching transistor Q3 with different specifications can be selected according to different circuit systems. The resistance value of the first resistor R1 and the capacitance of the third capacitor C3 are adjusted according to the actual device type. Preferably, the capacitance of the high-frequency ripple wave can be increased at the third capacitance C3 according to the actual working condition.
Further, the step-down power supply circuit with short-circuit protection further includes: and a second resistor R2, wherein the second resistor R2 is connected between the collector electrode of the third switching triode Q3 and the base electrode of the second switching triode Q2.
Through set up second resistance R2 between third switch triode Q3's collecting electrode and second switch triode Q2's base, can utilize second resistance R2's current-limiting effect protection second switch triode Q2 and third switch triode Q3, prevent second switch triode Q2's base electric current too big, the circuit appearance short circuit.
Further, the step-down power supply circuit with short-circuit protection further includes: the diode D1 is connected to the first capacitor C1 and the second capacitor C2.
By providing the diode D1 to connect the first capacitor C1 and the second capacitor C2, the discharge speed of the dc input terminal connected in parallel to the first capacitor C1 and the discharge speed of the load output terminal connected in parallel to the second capacitor C2 can be kept synchronous by the diode D1.
Further, when the load output end works normally, the zener diode Z1, the third switching transistor Q3, the second switching transistor Q2, and the first switching transistor Q1 are turned on in sequence, and a first loop, a second loop, and a third loop are formed, so that the voltages at two ends of the second capacitor C2, the base voltage of the first switching transistor Q1, and the emitter voltage of the first switching transistor Q1 are clamped by the zener diode Z1.
In a specific embodiment, when the load output end works normally, the first loop, the second loop and the third loop can be formed by sequentially conducting the zener diode Z1, the third switching triode Q3, the second switching triode Q2 and the first switching triode Q1, so that the voltage at two ends of the second capacitor C2, the base voltage of the first switching triode Q1 and the emitter voltage of the first switching triode Q1 can be clamped by the zener diode Z1, the voltage at two ends of the second capacitor C2, the base voltage of the first switching triode Q1 and the emitter voltage of the first switching triode Q1 are approximately equal to the conducting voltage of the zener diode Z1, and the working stability of the circuit can be improved.
Further, when the load output end works normally, the voltage at two ends of the third capacitor C3 is greater than the voltage at two ends of the zener diode Z1, and the zener diode Z1 and the third switching triode Q3 are conducted to form a first loop, so that the voltage at two ends of the second capacitor C2 is clamped by the zener diode Z1.
In a specific embodiment, when the load output end works normally, the voltage across the third capacitor C3 is greater than the voltage across the zener diode Z1, and the zener diode Z1 and the third switching triode Q3 are conducted to form a first loop. The current flows from the first capacitor C1, sequentially passes through the first resistor R1, the zener diode Z1, the base electrode of the third switching triode Q3, the emitter electrode of the third switching triode Q3 and returns to the first capacitor C1. At this time, the voltage across the second capacitor C2 is clamped by the zener diode Z1, which is approximately equal to the on voltage of the zener diode Z1.
Further, after the zener diode Z1 is turned on with the third switching transistor Q3, the second switching transistor Q2 is turned on to form the second loop, so that the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1.
In one embodiment, after the zener diode Z1 is turned on with the third switching transistor Q3, the second switching transistor Q2 is turned on to form a second loop. The current flows out from the third capacitor C3, flows through the emitter of the second switching triode Q2, the second resistor R2, the collector of the third switching triode Q3, the emitter of the third switching triode Q3 in sequence, and returns to the third capacitor C3. At this time, the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1, which is approximately equal to the turn-on voltage of the zener diode Z1.
Further, when the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1, the emitter voltage of the first switching transistor Q1 is clamped by the zener diode Z1, forming the third loop.
In one embodiment, when the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1, the emitter voltage of the first switching transistor Q1 follows the base voltage of the first switching transistor Q1, which is approximately equal to the turn-on voltage of the zener diode Z1, forming a third loop. The current flows out from the first capacitor C1, flows through the collector of the first switching triode Q1, the emitter of the first switching triode Q1, and the second capacitor C2 in sequence, and returns to the first capacitor C1.
Further, when a short circuit fault occurs at the load output end or the output voltage of the load output end is reduced abnormally, the voltage at two ends of the third capacitor C3 is smaller than the zener diode Z1, and the zener diode Z1 and the third switching triode Q3 are not conducted any more.
In a specific embodiment, when a short circuit fault occurs at the load output end or the output voltage of the load output end decreases abnormally, the load output end is at zero potential or low potential, at this time, the emitter frequency of the third switching triode Q3 is zero, the base voltage of the first switching triode Q1 decreases, the third switching triode Q3 cannot be turned on, and the zener diode Z1 cannot be turned on.
Further, when the zener diode Z1 and the third switching transistor Q3 are not turned on, the second switching transistor Q2 and the first switching transistor Q1 are not turned on.
In a specific embodiment, when the zener diode Z1 and the third switching transistor Q3 are no longer turned on, the collector voltage of the second switching transistor Q2 is smaller than the emitter voltage of the third switching transistor Q3, the second switching transistor Q2 is no longer turned on, and the first switching transistor Q1 is no longer turned on.
Further, when the second switching transistor Q2 and the first switching transistor Q1 are not turned on, the first resistor R1 charges the third capacitor C3, so that the zener diode Z1 is turned on to clamp the voltage across the second capacitor C2.
In a specific embodiment, when the second switching transistor Q2 and the first switching transistor Q1 are not turned on any more, the first resistor R1 charges the third capacitor C3 to turn on the zener diode Z1 again, and the operation is repeated until the fault disappears.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.
Claims (10)
1. A buck power supply circuit with short-circuit protection, the buck power supply circuit with short-circuit protection comprising: the voltage stabilizing diode Z1, the first switching triode Q1, the second switching triode Q2, the third switching triode Q3, the first capacitor C1, the second capacitor C2, the third capacitor C3 and the first resistor R1; the first capacitor C1 is connected with the direct current input end in parallel, and the second capacitor C2 is connected with the load output end in parallel; the third capacitor C3 is connected to the emitter of the second switching triode Q2 and the emitter of the third switching triode Q3; the positive electrode of the first capacitor C1 is connected with the base electrode of the third switching triode Q3 through the voltage stabilizing diode Z1; an emitter of the third switching triode Q3 is connected with a cathode of the first capacitor C1; an emitter of the second switching triode Q2 is connected with a collector of the third switching triode Q3; the base electrode of the first switching triode Q1 is connected with the collector electrode of the second switching triode Q2; the first resistor R1 is disposed between the first capacitor C1 and the zener diode Z1, and the first resistor R1 is connected in parallel with the third capacitor C3.
2. The buck power circuit with short-circuit protection according to claim 1, wherein the buck power circuit with short-circuit protection further includes:
and a second resistor R2, wherein the second resistor R2 is connected between the collector electrode of the third switching triode Q3 and the base electrode of the second switching triode Q2.
3. The buck power circuit with short-circuit protection according to claim 1, wherein the buck power circuit with short-circuit protection further includes:
the diode D1 is connected to the first capacitor C1 and the second capacitor C2.
4. A buck power supply circuit with short-circuit protection according to any of claims 1-3, wherein when the load output terminal is operating normally, the zener diode Z1, the third switching transistor Q3, the second switching transistor Q2 and the first switching transistor Q1 are turned on in sequence, and a first loop, a second loop and a third loop are formed, so that the voltage across the second capacitor C2, the base voltage of the first switching transistor Q1 and the emitter voltage of the first switching transistor Q1 are clamped by the zener diode Z1.
5. The buck power circuit with short-circuit protection according to claim 4, wherein,
when the load output end works normally, the voltage at two ends of the third capacitor C3 is larger than the voltage at two ends of the zener diode Z1, and the zener diode Z1 and the third switching triode Q3 are conducted to form a first loop, so that the voltage at two ends of the second capacitor C2 is clamped by the zener diode Z1.
6. The buck power circuit with short-circuit protection according to claim 5, wherein,
after the zener diode Z1 is turned on with the third switching transistor Q3, the second switching transistor Q2 is turned on to form the second loop, so that the base voltage of the first switching transistor Q1 is clamped by the zener diode Z1.
7. The buck power circuit with short-circuit protection according to claim 6, wherein,
when the base voltage of the first switching triode Q1 is clamped by the zener diode Z1, the emitter voltage of the first switching triode Q1 is clamped by the zener diode Z1, so as to form the third loop.
8. The buck power supply circuit with short-circuit protection according to claim 1, wherein when a short-circuit fault occurs at the load output terminal or the output voltage at the load output terminal decreases abnormally, the voltage across the third capacitor C3 is smaller than the zener diode Z1, and the zener diode Z1 is not turned on any more with the third switching transistor Q3.
9. The buck power circuit with short-circuit protection according to claim 8, wherein when the zener diode Z1 and the third switching transistor Q3 are no longer conductive, the second switching transistor Q2 and the first switching transistor Q1 are no longer conductive.
10. The buck power supply circuit with short-circuit protection according to claim 9, wherein when the second switching transistor Q2 and the first switching transistor Q1 are no longer conductive, the first resistor R1 charges the third capacitor C3 to cause the zener diode Z1 to be conductive to clamp the voltage across the second capacitor C2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320048258.3U CN219145257U (en) | 2023-01-03 | 2023-01-03 | Step-down power supply circuit with short-circuit protection |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320048258.3U CN219145257U (en) | 2023-01-03 | 2023-01-03 | Step-down power supply circuit with short-circuit protection |
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| Publication Number | Publication Date |
|---|---|
| CN219145257U true CN219145257U (en) | 2023-06-06 |
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| CN202320048258.3U Active CN219145257U (en) | 2023-01-03 | 2023-01-03 | Step-down power supply circuit with short-circuit protection |
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2023
- 2023-01-03 CN CN202320048258.3U patent/CN219145257U/en active Active
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