CN108322963B - Short circuit detection protection circuit - Google Patents
Short circuit detection protection circuit Download PDFInfo
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- CN108322963B CN108322963B CN201810231977.2A CN201810231977A CN108322963B CN 108322963 B CN108322963 B CN 108322963B CN 201810231977 A CN201810231977 A CN 201810231977A CN 108322963 B CN108322963 B CN 108322963B
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
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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
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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Abstract
The invention discloses a short circuit detection protection circuit, which comprises an LED driving circuit, wherein the LED driving circuit is electrically connected with an LED and comprises a first MOS tube; a protection circuit connected in parallel or in series with the LEDs; the two ends of the short circuit detection circuit are respectively and electrically connected with the protection circuit and the first MOS tube; when the short circuit detection circuit detects that the first MOS tube breaks down, the short circuit detection circuit sends a fault signal to the protection circuit so as to drive the protection circuit to execute protection action on the LED, so that the LED is effectively prevented from continuously heating, further, the carbonization of a PCB around the LED, the hot melting of a surrounding plastic structural member, the damage of an insulating layer and the like are avoided, and the risk of electric shock is reduced.
Description
Technical Field
The invention relates to the technical field of display, in particular to a short circuit detection protection circuit.
Background
Some conventional fluorescent lamp lighting products connected with inductive ballasts in the market are gradually replaced by LED products. In the LED product compatible with the inductive ballast, the driving circuit may be a buck circuit, as shown in fig. 1, when DS of a power MOS Q1 of the buck circuit breaks down and is shorted, the input mains supply forms a loop through the inductive ballast 1, the FUSE, the rectifier bridge DB1, the LED, the inductor L1, and the shorted MOS Q1. At this time, the LED current increases sharply. The increased LED current is insufficient to open the FUSE due to the current limiting of the inductive ballast, but may exceed the maximum current that the LED can withstand. In this state, the LED continues to heat, which can cause carbonization of the PCB around the LED and even hot melting of the surrounding plastic structural members, seriously damage the insulating layer, and risk electric shock.
Disclosure of Invention
The embodiment of the invention provides a short circuit detection protection circuit which is used for solving the problem that an LED continuously heats due to the fact that an MOS tube in the existing LED driving circuit breaks down.
The embodiment of the invention adopts the following technical scheme:
in a first aspect, the present invention provides a short circuit detection protection circuit, comprising:
the LED driving circuit is electrically connected with the LEDs and comprises a first MOS tube;
a protection circuit connected in parallel or in series with the LEDs;
the two ends of the short circuit detection circuit are respectively and electrically connected with the protection circuit and the first MOS tube;
when the short circuit detection circuit detects that the first MOS tube fails, the short circuit detection circuit sends a failure signal to the protection circuit so as to drive the protection circuit to execute protection action on the LED.
Further, the short circuit detection circuit includes: the first resistor, the second resistor, the third resistor, the first capacitor, the second capacitor, the first diode, the second diode and the first voltage stabilizing tube, wherein,
the two ends of the first resistor are respectively and electrically connected with the drain electrode of the first MOS tube and one end of the first capacitor, the other end of the first capacitor is respectively and electrically connected with the anode of the first diode and the cathode of the second diode, the cathode of the first diode is respectively and electrically connected with one end of the second capacitor, the cathode of the first voltage stabilizing tube and one end of the second resistor, the other end of the second resistor is respectively and electrically connected with one end of the third resistor and the protection circuit, and the other end of the third resistor, the anode of the first voltage stabilizing tube, the other end of the second capacitor and the anode of the second diode are electrically connected.
Further, the short circuit detection circuit includes: a first diode, a first resistor, a second resistor, a first capacitor and a first voltage stabilizing tube, wherein,
the positive electrode of the first diode is respectively and electrically connected with the drain electrode of the first MOS tube and one end of the first resistor, the other end of the first resistor is respectively and electrically connected with one end of the first capacitor, the negative electrode of the first voltage stabilizing tube, one end of the second resistor and the protection circuit, and the other end of the second resistor, the positive electrode of the first voltage stabilizing tube and the other end of the first capacitor are electrically connected.
Further, the protection circuit comprises a second MOS tube; wherein,
the drain electrode of the second MOS tube is electrically connected with the negative electrode of the LED;
the source electrode of the second MOS tube is electrically connected with the other end of the third resistor, the positive electrode of the first voltage stabilizing tube, the other end of the second capacitor and the positive electrode of the second diode;
and the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the second resistor and one end of the third resistor.
Further, the protection circuit includes: a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a second voltage stabilizing tube, a first thyristor and a second MOS tube, wherein,
the drain electrode of the second MOS tube is respectively and electrically connected with one end of the fourth resistor, the negative electrode of the second voltage stabilizing tube and one end of the sixth resistor, the other end of the fourth resistor is electrically connected with the positive electrode of the LED, the positive electrode of the second voltage stabilizing tube is respectively and electrically connected with one end of the seventh resistor, one end of the third capacitor and the control electrode of the first thyristor, the anode of the first thyristor is electrically connected with one end of the fifth resistor, and the other end of the fifth resistor is electrically connected with the positive electrode of the LED;
the source electrode of the second MOS tube, the cathode of the first thyristor, the other end of the seventh resistor, the other end of the third capacitor, the other end of the sixth resistor, the other end of the third resistor, the positive electrode of the first voltage stabilizing tube, the other end of the second capacitor and the positive electrode of the second diode are electrically connected;
and the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the second resistor and one end of the third resistor.
Further, the protection circuit comprises a second MOS tube; wherein,
the drain electrode of the second MOS tube is electrically connected with the negative electrode of the LED;
the source electrode of the second MOS tube is electrically connected with the short circuit detection circuit;
and the grid electrode of the second MOS tube is electrically connected with the short circuit detection circuit.
Further, the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the first resistor, one end of the first capacitor, the negative electrode of the first voltage stabilizing tube and one end of the second resistor;
the source electrode of the second MOS tube is respectively and electrically connected with the other end of the second resistor, the positive electrode of the first voltage stabilizing tube and the other end of the first capacitor.
Further, the protection circuit includes: a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a second voltage stabilizing tube, a first thyristor and a second MOS tube, wherein,
the drain electrode of the second MOS tube is respectively and electrically connected with one end of the fourth resistor, the negative electrode of the second voltage stabilizing tube and one end of the sixth resistor, the other end of the fourth resistor is electrically connected with the positive electrode of the LED, the positive electrode of the second voltage stabilizing tube is respectively and electrically connected with one end of the seventh resistor, one end of the third capacitor and the control electrode of the first thyristor, the anode of the first thyristor is electrically connected with one end of the fifth resistor, and the other end of the fifth resistor is electrically connected with the positive electrode of the LED;
the source electrode of the second MOS tube, the cathode of the first thyristor, the other end of the seventh resistor, the other end of the third capacitor and the other end of the sixth resistor are electrically connected with the short circuit detection circuit;
and the grid electrode of the second MOS tube is electrically connected with the short circuit detection circuit.
Further, the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the first resistor, one end of the first capacitor, the negative electrode of the first voltage stabilizing tube and one end of the second resistor;
the source electrode of the second MOS tube is respectively and electrically connected with the other end of the second resistor, the positive electrode of the first voltage stabilizing tube and the other end of the first capacitor.
Further, the LED driving circuit is a BUCK circuit.
Further, the BUCK circuit includes: the fuse, the rectifier bridge, the first polar capacitor, the second polar capacitor, the first diode, the first resistor, the second resistor and the first inductor, wherein,
one end of the fuse is electrically connected with the inductive ballast, the other end of the fuse is electrically connected with the first end of the rectifier bridge, the second end of the rectifier bridge is respectively electrically connected with the positive electrode of the first polarity capacitor, the negative electrode of the first diode, the positive electrode of the second polarity capacitor, one end of the first resistor and the positive electrode of the LED, the third end of the rectifier bridge is electrically connected with the zero line, the fourth end of the rectifier bridge is respectively electrically connected with the negative electrode of the first polarity capacitor and one end of the second resistor, the other end of the second resistor is electrically connected with the source electrode of the first MOS tube, the drain electrode of the first MOS tube is electrically connected with one end of the first inductor, the other end of the first inductor is respectively electrically connected with the negative electrode of the second polarity capacitor and the other end of the first resistor, and the grid electrode of the first MOS tube is connected with a driving signal.
The above at least one technical scheme adopted by the embodiment of the invention can achieve the following beneficial effects:
the short circuit detection protection circuit comprises an LED driving circuit, a protection circuit and a short circuit detection circuit, wherein the LED driving circuit is electrically connected with an LED, the LED driving circuit comprises a first MOS tube, the protection circuit is connected with the LED in parallel or in series, and two ends of the short circuit detection circuit are respectively electrically connected with the protection circuit and the first MOS tube. When the short circuit detection circuit detects that the first MOS tube breaks down, the short circuit detection circuit sends a fault signal to the protection circuit so as to drive the protection circuit to execute protection action on the LED, thereby effectively avoiding continuous heating of the LED, further avoiding carbonization of a PCB around the LED, hot melting of surrounding plastic structural members, damage of an insulating layer and the like, and reducing the risk of electric shock.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and do not constitute a limitation on the invention. In the drawings:
fig. 1 is a schematic diagram of a prior art LED driving circuit;
fig. 2 is a schematic structural diagram of a short-circuit detection protection circuit according to an embodiment of the present invention;
FIG. 3 is a second schematic diagram of a short-circuit detection protection circuit according to an embodiment of the present invention;
FIG. 4 is a third schematic diagram of a short-circuit detection protection circuit according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a short-circuit detection protection circuit according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a short-circuit detection protection circuit according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a short-circuit detection protection circuit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The short circuit detection protection circuit provided by the embodiment of the invention comprises: an LED driving circuit 10, a protection circuit 20, and a short detection circuit 30. The LED driving circuit 10 may have a circuit structure in the prior art, and the LED driving circuit is electrically connected to the LED, where the LED driving circuit includes a first MOS transistor.
In implementation, the LED driving circuit 10 may be a BUCK circuit, and the BUCK circuit may include: the device comprises a fuse F1, a rectifier bridge DB1, a first polarity capacitor EC1, a second polarity capacitor EC2, a first diode D01, a first resistor R01, a second resistor R02 and a first inductor L1.
One end of the fuse F1 is electrically connected to the inductive ballast, the other end of the fuse F1 is electrically connected to the first end of the rectifier bridge DB1, the second end of the rectifier bridge DB1 is electrically connected to the positive electrode of the first polarity capacitor EC1, the negative electrode of the first diode D01, the positive electrode of the second polarity capacitor EC2, one end of the first resistor R01 and the positive electrode of the LED respectively, the third end of the rectifier bridge DB1 is electrically connected to the zero line, the fourth end of the rectifier bridge DB1 is electrically connected to the negative electrode of the first polarity capacitor EC1 and one end of the second resistor R02 respectively, the other end of the second resistor R02 is electrically connected to the source electrode of the first MOS transistor, the drain electrode of the first MOS transistor is electrically connected to one end of the first inductor L1, the other end of the first inductor L1 is electrically connected to the negative electrode of the second polarity capacitor EC2, the other end of the first resistor R01 respectively, and the gate electrode of the first MOS transistor is connected to the constant current driving integrated circuit IC for accessing the gate electrode of the first MOS transistor to the driving signal.
The working principle of the BUCK circuit is as follows: when the driving signal accessed by the grid electrode of the first MOS tube Q1 is a high-level signal, the drain electrode and the source electrode of the first MOS tube Q1 are conducted, the first inductor L1 is magnetized, the current flowing through the first inductor L1 is increased linearly, and meanwhile the second polar capacitor EC2 is charged, so that energy is provided for the load LED; when the driving signal connected to the gate of the first MOS transistor Q1 is a low level signal, the first MOS transistor Q1 is turned off, the first inductor L1 discharges through the freewheeling first diode D01, and the current flowing through the first inductor L1 decreases linearly, so that the energy provided to the load LED is maintained by the discharging of the second diode capacitor EC2 and the reduced current of the first inductor L1. The second resistor R02 is a current sampling resistor, the rectifier bridge DB1 is used for rectifying, and the first polarity capacitor EC1 is used for filtering.
Of course, other structures may be adopted for the implementation structure of the LED driving circuit, and the embodiment of the present invention is not limited in particular. The specific implementation is set according to the actual requirement.
The circuit connection structure of the short circuit detection protection circuit provided by the embodiment of the invention is as follows:
first, as shown in fig. 2, the protection circuit 20 is connected in parallel with the LEDs. Both ends of the short circuit detection circuit 30 are electrically connected to the protection circuit 20 and the first MOS transistor Q1, respectively. When the short circuit detection circuit 30 detects that the first MOS transistor Q1 fails, the short circuit detection circuit 30 sends a failure signal to the protection circuit 20 to drive the protection circuit 20 to perform a protection action on the LED.
Second, as shown in fig. 3, a protection circuit 20 is connected in series with the LEDs. Both ends of the short circuit detection circuit 30 are electrically connected to the protection circuit 20 and the first MOS transistor Q1, respectively. When the short circuit detection circuit 30 detects that the first MOS transistor Q1 fails, the short circuit detection circuit 30 sends a failure signal to the protection circuit 20 to drive the protection circuit 20 to perform a protection action on the LED.
The short circuit detection protection circuit comprises an LED driving circuit, a protection circuit and a short circuit detection circuit, wherein the LED driving circuit is electrically connected with an LED, the LED driving circuit comprises a first MOS tube, the protection circuit is connected with the LED in parallel or in series, and two ends of the short circuit detection circuit are respectively electrically connected with the protection circuit and the first MOS tube. When the short circuit detection circuit detects that the first MOS tube breaks down, the short circuit detection circuit sends a fault signal to the protection circuit so as to drive the protection circuit to execute protection action on the LED, thereby effectively avoiding continuous heating of the LED, further avoiding carbonization of a PCB around the LED, hot melting of surrounding plastic structural members, damage of an insulating layer and the like, and reducing the risk of electric shock.
The specific implementation structure of the short circuit detection circuit 30 in the above embodiment may be various, and the embodiment of the present invention is not limited in particular. In specific implementation, the short-circuit detection circuit 30 may have the following structures, for example:
the short circuit detection circuit 30 of the first structure, the short circuit detection circuit 30 may include: the first resistor, the second resistor, the third resistor, the first capacitor, the second capacitor, the first diode, the second diode and the first voltage stabilizing tube, wherein,
the both ends of first resistance are connected with the drain electrode of first MOS pipe and the one end electricity of first electric capacity respectively, the other end of first electric capacity is connected with the positive pole of first diode and the negative pole electricity of second diode respectively, the negative pole of first diode is connected with the one end of second electric capacity respectively, the negative pole of first steady voltage tube, the one end electricity of second resistance, the other end of second resistance is connected with the one end and the protection circuit 20 electricity of third resistance respectively, the other end of third resistance, the positive pole of first steady voltage tube, the other end of second electric capacity and the positive pole electricity of second diode are connected.
The frequency of the first MOS transistor during normal operation may be 30K-100KHZ, and of course, the frequency of the first MOS transistor during normal operation may also be other power, which is not limited during implementation. The first resistor and the first capacitor are used for high-frequency power taking, the first diode and the second diode play a role in rectification, the second capacitor is a filter capacitor, and the first voltage stabilizing tube is used for stabilizing voltage to direct-current voltage.
The short circuit detection circuit 30 of the second structure, the short circuit detection circuit 30 may include: a first diode, a first resistor, a second resistor, a first capacitor and a first voltage stabilizing tube, wherein,
the positive pole of first diode is connected with the drain electrode of first MOS pipe and the one end electricity of first resistance respectively, and the other end of first resistance is connected with the one end of first electric capacity, the negative pole of first steady voltage tube, the one end and the protection circuit 20 electricity of second resistance respectively, and the other end of second resistance, the positive pole of first steady voltage tube and the other end electricity of first electric capacity are connected.
The frequency of the first MOS transistor during normal operation may be 30K-100KHZ, and of course, the frequency of the first MOS transistor during normal operation may also be other power, which is not limited during implementation. The first diode is used for rectification, the first resistor and the first capacitor are used for filtering, the first voltage stabilizing tube is used for limiting voltage, and the second resistor is used for limiting current.
The specific implementation structure of the protection circuit 20 in the above embodiment may be various, and the embodiment of the present invention is not limited in particular. In specific implementation, the protection circuit 20 may have the following structures, for example:
the protection circuit 20 of the first structure, the protection circuit 20 may include a second MOS transistor; wherein,
the drain electrode of the second MOS tube is electrically connected with the negative electrode of the LED;
the source electrode of the second MOS tube is electrically connected with the short circuit detection circuit 30;
the gate of the second MOS transistor is electrically connected to the short detection circuit 30.
The protection circuit 20 of the second structure, the protection circuit 20 may include: a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a second voltage stabilizing tube, a first thyristor and a second MOS tube, wherein,
the drain electrode of the second MOS tube is respectively and electrically connected with one end of a fourth resistor, the negative electrode of the second voltage stabilizing tube and one end of a sixth resistor, the other end of the fourth resistor is electrically connected with the positive electrode of the LED, the positive electrode of the second voltage stabilizing tube is respectively and electrically connected with one end of a seventh resistor, one end of a third capacitor and the control electrode of the first thyristor, the anode of the first thyristor is electrically connected with one end of a fifth resistor, and the other end of the fifth resistor is electrically connected with the positive electrode of the LED;
the source electrode of the second MOS tube, the cathode of the first thyristor, the other end of the seventh resistor, the other end of the third capacitor and the other end of the sixth resistor are electrically connected with the short circuit detection circuit 30;
the gate of the second MOS transistor is electrically connected to the short detection circuit 30.
The fourth resistor and the sixth resistor jointly determine overvoltage protection on the output opening, the fifth resistor is a current-limiting resistor, the seventh resistor provides a discharge path for the third capacitor when the second voltage-stabilizing tube is cut off, meanwhile, the seventh resistor can prevent the control electrode of the first thyristor from being triggered by mistake when the second voltage-stabilizing tube is cut off, and the third capacitor is used for filtering.
In specific implementation, the above-mentioned short circuit detection circuit 30 with the first structure, the short circuit detection circuit 30 with the second structure, the protection circuit 20 with the first structure, and the protection circuit 20 with the second structure may be combined two by two to form a short circuit detection protection circuit with four structures, which is as follows:
first, as shown in fig. 4, the short detection protection circuit includes an LED driving circuit 10, a short detection circuit 30, and a protection circuit 20.
The short circuit detection circuit 30 may include: the first resistor R1, the second resistor R2, the third resistor R3, the first capacitor C1, the second capacitor C2, the first diode D1, the second diode D2 and the first voltage stabilizing tube ZD1, wherein,
the two ends of the first resistor R1 are respectively and electrically connected with the drain electrode of the first MOS tube and one end of the first capacitor C1, the other end of the first capacitor C1 is respectively and electrically connected with the anode of the first diode D1 and the cathode of the second diode D2, the cathode of the first diode D1 is respectively and electrically connected with one end of the second capacitor C2, the cathode of the first voltage stabilizing tube ZD1 and one end of the second resistor R2, the other end of the second resistor R2 is respectively and electrically connected with one end of the third resistor R3 and the protection circuit 20, and the other end of the third resistor R3, the anode of the first voltage stabilizing tube ZD1, the other end of the second capacitor C2 and the anode of the second diode D2 are electrically connected.
The protection circuit 20 is connected in parallel with the LED, and specifically may be implemented as: the protection circuit 20 may include: a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, a second voltage stabilizing tube ZD2, a first thyristor SCR1 and a second MOS tube Q2, wherein,
the drain electrode of the second MOS tube Q2 is respectively and electrically connected with one end of a fourth resistor R4, the negative electrode of a second voltage stabilizing tube ZD2 and one end of a sixth resistor R6, the other end of the fourth resistor R4 is electrically connected with the positive electrode of the LED, the positive electrode of the second voltage stabilizing tube ZD2 is respectively and electrically connected with one end of a seventh resistor R7, one end of a third capacitor C3 and the control electrode of a first thyristor SCR1, the anode of the first thyristor SCR1 is electrically connected with one end of a fifth resistor R5, and the other end of the fifth resistor R5 is electrically connected with the positive electrode of the LED;
the source electrode of the second MOS tube Q2, the cathode of the first thyristor SCR1, the other end of the seventh resistor R7, the other end of the third capacitor C3, the other end of the sixth resistor R6, the other end of the third resistor R3, the positive electrode of the first voltage stabilizing tube ZD1, the other end of the second capacitor C2 and the positive electrode of the second diode D2 are electrically connected;
the grid electrode of the second MOS tube Q2 is respectively and electrically connected with the other end of the second resistor R2 and one end of the third resistor R3.
The working principle of the short circuit detection protection circuit with the first structure provided by the embodiment of the invention is as follows: when the first MOS transistor Q1 works normally, the drain of the first MOS transistor Q1 is a high-frequency switching signal, and a high-frequency current flows through the first resistor R1, the first capacitor C1, the first diode D1, the second resistor R2 to the gate of the second MOS transistor Q2, and the gate-source voltage of the second MOS transistor Q2 is high. At this time, the second MOS transistor Q2 is turned on, a part of current at the positive electrode of the LED flows through the fourth resistor R4 and the drain-source electrode of the second MOS transistor Q2, and the second voltage regulator ZD2 and the first thyristor SCR1 are turned off; when the first MOS transistor Q1 has a drain-source short circuit fault, the drain-source voltage of the first MOS transistor Q1 is a dc signal, no current flows into the gate of the second MOS transistor Q2 through the first capacitor C1, and the gate-source voltage of the second MOS transistor Q2 is low. At this time, the second MOS transistor Q2 is turned off, the current at the positive electrode of the LED flows through the fourth resistor R4 and the second voltage stabilizing tube ZD2 to the control electrode of the first thyristor SCR1, the first thyristor SCR1 is triggered and turned on, and the fifth resistor R5 and the first thyristor SCR1 are equivalent to the conductive wires because the on-resistance of the fifth resistor R5 and the first thyristor SCR1 is very small, and after the first thyristor SCR1 is triggered and turned on, the current at the positive electrode of the LED flows through the fifth resistor R5 and the first thyristor SCR1 to short-circuit the LED, thereby achieving the purpose of protecting the LED.
Second, as shown in fig. 5, the short detection protection circuit includes an LED driving circuit 10, a short detection circuit 30, and a protection circuit 20.
The short circuit detection circuit 30 may include: the first resistor R1, the second resistor R2, the third resistor R3, the first capacitor C1, the second capacitor C2, the first diode D1, the second diode D2 and the first voltage stabilizing tube ZD1, wherein,
the two ends of the first resistor R1 are respectively and electrically connected with the drain electrode of the first MOS tube and one end of the first capacitor C1, the other end of the first capacitor C1 is respectively and electrically connected with the anode of the first diode D1 and the cathode of the second diode D2, the cathode of the first diode D1 is respectively and electrically connected with one end of the second capacitor C2, the cathode of the first voltage stabilizing tube ZD1 and one end of the second resistor R2, the other end of the second resistor R2 is respectively and electrically connected with one end of the third resistor R3 and the protection circuit 20, and the other end of the third resistor R3, the anode of the first voltage stabilizing tube ZD1, the other end of the second capacitor C2 and the anode of the second diode D2 are electrically connected.
The protection circuit 20 is connected in series with the LED, and can be specifically implemented as: the protection circuit 20 may include a second MOS transistor Q2; wherein,
the drain electrode of the second MOS tube Q2 is electrically connected with the cathode of the LED;
the source electrode of the second MOS tube Q2 is electrically connected with the other end of the third resistor R3, the positive electrode of the first voltage stabilizing tube ZD1, the other end of the second capacitor C2 and the positive electrode of the second diode D2;
the grid electrode of the second MOS tube Q2 is respectively and electrically connected with the other end of the second resistor R2 and one end of the third resistor R3.
The working principle of the short circuit detection protection circuit with the second structure provided by the embodiment of the invention is as follows: when the first MOS transistor Q1 works normally, the drain of the first MOS transistor Q1 is a high-frequency switching signal, and a high-frequency current flows through the first resistor R1, the first capacitor C1, the first diode D1, the second resistor R2 to the gate of the second MOS transistor Q2, and the gate-source voltage of the second MOS transistor Q2 is high. At this time, the second MOS transistor Q2 is conducted, and the current at the positive electrode of the LED flows through the LED and the drain-source electrode of the second MOS transistor Q2; when the first MOS transistor Q1 has a drain-source short circuit fault, the drain-source voltage of the first MOS transistor Q1 is a dc signal, no current flows into the gate of the second MOS transistor Q2 through the first capacitor C1, and the gate-source voltage of the second MOS transistor Q2 is low. At this time, the second MOS transistor Q2 is turned off, and no current flows through the LED, thereby achieving the purpose of protecting the LED.
Third, as shown in fig. 6, the short detection protection circuit includes an LED driving circuit 10, a short detection circuit 30, and a protection circuit 20.
The short circuit detection circuit 30 may include: a first diode D1, a first resistor R1, a second resistor R2, a first capacitor C1 and a first voltage stabilizing tube ZD1, wherein,
the positive pole of first diode D1 is connected with the drain electrode of first MOS pipe and the one end electricity of first resistance R1 respectively, and the other end of first resistance R1 is connected with the one end of first electric capacity C1, the negative pole of first voltage regulator ZD1, one end and the protection circuit 20 electricity of second resistance R2 respectively, and the other end of second resistance R2, the positive pole of first voltage regulator ZD1 and the other end electricity of first electric capacity C1 are connected.
The protection circuit 20 is connected in parallel with the LED, and specifically may be implemented as: the protection circuit 20 may include: a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, a second voltage stabilizing tube ZD2, a first thyristor SCR1 and a second MOS tube Q2, wherein,
the drain electrode of the second MOS tube Q2 is respectively and electrically connected with one end of a fourth resistor R4, the negative electrode of a second voltage stabilizing tube ZD2 and one end of a sixth resistor R6, the other end of the fourth resistor R4 is electrically connected with the positive electrode of the LED, the positive electrode of the second voltage stabilizing tube ZD2 is respectively and electrically connected with one end of a seventh resistor R7, one end of a third capacitor C3 and the control electrode of a first thyristor SCR1, the anode of the first thyristor SCR1 is electrically connected with one end of a fifth resistor R5, and the other end of the fifth resistor R5 is electrically connected with the positive electrode of the LED;
the source electrode of the second MOS tube Q2, the cathode of the first thyristor SCR1, the other end of the seventh resistor R7, the other end of the third capacitor C3, the other end of the sixth resistor R6, the other end of the second resistor R2, the anode of the first voltage stabilizing tube ZD1 and the other end of the first capacitor C1 are electrically connected;
the grid electrode of the second MOS tube Q2 is respectively and electrically connected with the other end of the first resistor R1, one end of the first capacitor C1, the negative electrode of the first voltage stabilizing tube ZD1 and one end of the second resistor R2.
The working principle of the short circuit detection protection circuit with the third structure provided by the embodiment of the invention is as follows: when the first MOS transistor Q1 works normally, the drain of the first MOS transistor Q1 is a high-frequency switching signal, and a high-frequency current flows through the first diode D1, the first resistor R1 to the gate of the second MOS transistor Q2, and the gate-source voltage of the second MOS transistor Q2 is high. At this time, the second MOS transistor Q2 is turned on, a part of current at the positive electrode of the LED flows through the fourth resistor R4 and the drain-source electrode of the second MOS transistor Q2, and the second voltage regulator ZD2 and the first thyristor SCR1 are turned off; when the first MOS transistor Q1 has a short-circuit fault, the drain-source voltages of the first MOS transistor Q1 are the same and are low, the first diode D1 is turned off, no current flows into the grid electrode of the second MOS transistor Q2, and the grid-source voltage of the second MOS transistor Q2 is low. At this time, the second MOS transistor Q2 is turned off, the current at the positive electrode of the LED flows through the fourth resistor R4 and the second voltage stabilizing tube ZD2 to the control electrode of the first thyristor SCR1, the first thyristor SCR1 is triggered and turned on, and the fifth resistor R5 and the first thyristor SCR1 are equivalent to the conductive wires because the on-resistance of the fifth resistor R5 and the first thyristor SCR1 is very small, and after the first thyristor SCR1 is triggered and turned on, the current at the positive electrode of the LED flows through the sixth resistor R6 and the first thyristor SCR1, so as to short-circuit the LED, thereby achieving the purpose of protecting the LED.
Fourth, as shown in fig. 7, the short detection protection circuit includes an LED driving circuit 10, a short detection circuit 30, and a protection circuit 20.
The short circuit detection circuit 30 may include: a first diode D1, a first resistor R1, a second resistor R2, a first capacitor C1 and a first voltage stabilizing tube ZD1, wherein,
the positive pole of first diode D1 is connected with the drain electrode of first MOS pipe and the one end electricity of first resistance R1 respectively, and the other end of first resistance R1 is connected with the one end of first electric capacity C1, the negative pole of first voltage regulator ZD1, one end and the protection circuit 20 electricity of second resistance R2 respectively, and the other end of second resistance R2, the positive pole of first voltage regulator ZD1 and the other end electricity of first electric capacity C1 are connected.
The protection circuit 20 is connected in series with the LED, and can be specifically implemented as: the protection circuit 20 may include a second MOS transistor Q2; wherein,
the drain electrode of the second MOS tube Q2 is electrically connected with the cathode of the LED;
the source electrode of the second MOS tube Q2 is respectively and electrically connected with the other end of the second resistor R2, the positive electrode of the first voltage stabilizing tube ZD1 and the other end of the first capacitor C1;
the grid electrode of the second MOS tube Q2 is respectively and electrically connected with the other end of the first resistor R1, one end of the first capacitor C1, the negative electrode of the first voltage stabilizing tube ZD1 and one end of the second resistor R2.
The working principle of the short circuit detection protection circuit with the fourth structure provided by the embodiment of the invention is as follows: when the first MOS transistor Q1 works normally, the drain of the first MOS transistor Q1 is a high-frequency switching signal, and a high-frequency current flows through the first diode D1, the first resistor R1 to the gate of the second MOS transistor Q2, and the gate-source voltage of the second MOS transistor Q2 is high. At this time, the second MOS transistor Q2 is conducted, and the current at the positive electrode of the LED flows through the LED and the drain-source electrode of the second MOS transistor Q2; when the first MOS transistor Q1 has a short-circuit fault, the drain-source voltages of the first MOS transistor Q1 are the same and are low, the first diode D1 is turned off, no current flows into the grid electrode of the second MOS transistor Q2, and the grid-source voltage of the second MOS transistor Q2 is low. At this time, the second MOS transistor Q2 is turned off, and no current flows through the LED, thereby achieving the purpose of protecting the LED.
It will be apparent to those skilled in the art that while preferred embodiments of the present invention have been described, additional variations and modifications may be made to these embodiments once the basic inventive concepts are known to those skilled in the art. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (9)
1. A short circuit detection protection circuit, comprising:
the LED driving circuit is electrically connected with the LEDs and comprises a first MOS tube;
a protection circuit connected in parallel or in series with the LEDs;
the two ends of the short circuit detection circuit are respectively and directly electrically connected with the protection circuit and the first MOS tube;
when the short circuit detection circuit detects that the first MOS tube fails, the short circuit detection circuit sends a failure signal to the protection circuit so as to drive the protection circuit to execute protection action on the LED.
2. The short circuit detection protection circuit according to claim 1, wherein,
the short circuit detection circuit includes: the first resistor, the second resistor, the third resistor, the first capacitor, the second capacitor, the first diode, the second diode and the first voltage stabilizing tube, wherein,
the two ends of the first resistor are respectively and electrically connected with the drain electrode of the first MOS tube and one end of the first capacitor, the other end of the first capacitor is respectively and electrically connected with the anode of the first diode and the cathode of the second diode, the cathode of the first diode is respectively and electrically connected with one end of the second capacitor, the cathode of the first voltage stabilizing tube and one end of the second resistor, the other end of the second resistor is respectively and electrically connected with one end of the third resistor and the protection circuit, and the other end of the third resistor, the anode of the first voltage stabilizing tube, the other end of the second capacitor and the anode of the second diode are electrically connected.
3. The short circuit detection protection circuit according to claim 1, wherein,
the short circuit detection circuit includes: a first diode, a first resistor, a second resistor, a first capacitor and a first voltage stabilizing tube, wherein,
the positive electrode of the first diode is respectively and electrically connected with the drain electrode of the first MOS tube and one end of the first resistor, the other end of the first resistor is respectively and electrically connected with one end of the first capacitor, the negative electrode of the first voltage stabilizing tube, one end of the second resistor and the protection circuit, and the other end of the second resistor, the positive electrode of the first voltage stabilizing tube and the other end of the first capacitor are electrically connected.
4. The short circuit detection protection circuit according to claim 2, wherein,
the protection circuit comprises a second MOS tube; wherein,
the drain electrode of the second MOS tube is electrically connected with the negative electrode of the LED;
the source electrode of the second MOS tube is electrically connected with the other end of the third resistor, the positive electrode of the first voltage stabilizing tube, the other end of the second capacitor and the positive electrode of the second diode;
and the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the second resistor and one end of the third resistor.
5. The short circuit detection protection circuit according to claim 2, wherein,
the protection circuit includes: a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a second voltage stabilizing tube, a first thyristor and a second MOS tube, wherein,
the drain electrode of the second MOS tube is respectively and electrically connected with one end of the fourth resistor, the negative electrode of the second voltage stabilizing tube and one end of the sixth resistor, the other end of the fourth resistor is electrically connected with the positive electrode of the LED, the positive electrode of the second voltage stabilizing tube is respectively and electrically connected with one end of the seventh resistor, one end of the third capacitor and the control electrode of the first thyristor, the anode of the first thyristor is electrically connected with one end of the fifth resistor, and the other end of the fifth resistor is electrically connected with the positive electrode of the LED;
the source electrode of the second MOS tube, the cathode of the first thyristor, the other end of the seventh resistor, the other end of the third capacitor, the other end of the sixth resistor, the other end of the third resistor, the positive electrode of the first voltage stabilizing tube, the other end of the second capacitor and the positive electrode of the second diode are electrically connected;
and the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the second resistor and one end of the third resistor.
6. The short-circuit detection protection circuit according to claim 3, wherein,
the protection circuit comprises a second MOS tube; wherein,
the drain electrode of the second MOS tube is electrically connected with the negative electrode of the LED;
the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the first resistor, one end of the first capacitor, the negative electrode of the first voltage stabilizing tube and one end of the second resistor;
the source electrode of the second MOS tube is respectively and electrically connected with the other end of the second resistor, the positive electrode of the first voltage stabilizing tube and the other end of the first capacitor.
7. The short-circuit detection protection circuit according to claim 3, wherein,
the protection circuit includes: a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a second voltage stabilizing tube, a first thyristor and a second MOS tube, wherein,
the drain electrode of the second MOS tube is respectively and electrically connected with one end of the fourth resistor, the negative electrode of the second voltage stabilizing tube and one end of the sixth resistor, the other end of the fourth resistor is electrically connected with the positive electrode of the LED, the positive electrode of the second voltage stabilizing tube is respectively and electrically connected with one end of the seventh resistor, one end of the third capacitor and the control electrode of the first thyristor, the anode of the first thyristor is electrically connected with one end of the fifth resistor, and the other end of the fifth resistor is electrically connected with the positive electrode of the LED;
the source electrode of the second MOS tube, the cathode of the first thyristor, the other end of the seventh resistor, the other end of the third capacitor and the other end of the sixth resistor are electrically connected with the other end of the second resistor, the anode of the first voltage stabilizing tube and the other end of the first capacitor;
the grid electrode of the second MOS tube is respectively and electrically connected with the other end of the first resistor, one end of the first capacitor, the negative electrode of the first voltage stabilizing tube and one end of the second resistor.
8. The short circuit detection protection circuit according to claim 1, wherein,
the LED driving circuit is a BUCK circuit.
9. The short circuit detection protection circuit of claim 8, wherein,
the BUCK circuit includes: the fuse, the rectifier bridge, the first polar capacitor, the second polar capacitor, the first diode, the first resistor, the second resistor and the first inductor, wherein,
one end of the fuse is electrically connected with the inductive ballast, the other end of the fuse is electrically connected with the first end of the rectifier bridge, the second end of the rectifier bridge is respectively electrically connected with the positive electrode of the first polarity capacitor, the negative electrode of the first diode, the positive electrode of the second polarity capacitor, one end of the first resistor and the positive electrode of the LED, the third end of the rectifier bridge is electrically connected with the zero line, the fourth end of the rectifier bridge is respectively electrically connected with the negative electrode of the first polarity capacitor and one end of the second resistor, the other end of the second resistor is electrically connected with the source electrode of the first MOS tube, the drain electrode of the first MOS tube is electrically connected with one end of the first inductor, the other end of the first inductor is respectively electrically connected with the negative electrode of the second polarity capacitor and the other end of the first resistor, and the grid electrode of the first MOS tube is connected with a driving signal.
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