CN113225875B - Drive power supply and output short-circuit protection circuit thereof - Google Patents

Drive power supply and output short-circuit protection circuit thereof Download PDF

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Publication number
CN113225875B
CN113225875B CN202110423730.2A CN202110423730A CN113225875B CN 113225875 B CN113225875 B CN 113225875B CN 202110423730 A CN202110423730 A CN 202110423730A CN 113225875 B CN113225875 B CN 113225875B
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circuit
voltage
resistor
output
comparator
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CN113225875A (en
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王宗友
潘松
邹超洋
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Shenzhen Sosen Electronics Co Ltd
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Shenzhen Sosen Electronics Co Ltd
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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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/30—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels
    • G09G3/32—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using electroluminescent panels semiconductive, e.g. using light-emitting diodes [LED]
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • 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]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • 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]

Abstract

The invention relates to a driving power supply and an output short-circuit protection circuit thereof, comprising a voltage sampling circuit, a comparison circuit and a current reference regulating circuit; the input end of the voltage sampling circuit is connected with the output end of the driving power supply, the output end of the voltage sampling circuit is connected with the second input end of the comparison circuit, the first input end of the comparison circuit is connected with reference voltage, the output end of the comparison circuit is connected with the input end of the current reference regulating circuit, and the output end of the current reference regulating circuit is connected to the current reference signal input end of the current control loop; the voltage sampling circuit samples the output voltage of the driving power supply and outputs a voltage sampling signal; the comparison circuit compares the voltage sampling signal with a reference voltage and outputs a conducting signal when the voltage of the voltage sampling signal is smaller than the reference voltage; the current reference adjusting circuit is conducted according to the conducting signal to reduce the reference current. This practicality is through discerning the short circuit and reducing reference current at power secondary side, avoids the circuit out of control, effective protection circuit and power.

Description

Driving power supply and output short-circuit protection circuit thereof
Technical Field
The invention relates to the technical field of driving power supplies, in particular to a driving power supply and an output short-circuit protection circuit thereof.
Background
The LED driving power supply generally adopts a constant output current mode to supply power to a load, the output current is constant, the output voltage is related to the quantity of load LED lamp beads, the existing short-circuit protection is realized by identifying that the load becomes very large after short circuit, so that the primary side working current is increased at a very high speed to trigger the primary side control chip to close the output by an overcurrent threshold value, and the protection function is realized.
The existing protection function is realized by the following flows: short circuit output → theoretically load becoming infinite → secondary side working current surge → transfer to primary side working current surge through transformer → primary side sampling working current state exceeding control chip protection threshold → chip closing drive output → circuit shutdown.
It can be seen from the above working flows that the circuit works in a complete out-of-control state in the time period from the short circuit occurrence time to the time when the control chip closes the output after recognizing the short circuit fault. When a short-circuit fault occurs, a very large impact current is generated in a rectifier element, a filter element, a transformer and a primary side power switching tube on the secondary side, the impact current continuously rises until the control chip closes the output after identifying the fault and stops working, and the power device is irreversibly damaged by the strong impact current, so that the service life and the reliability of the product are finally influenced.
Disclosure of Invention
The present invention provides a driving power supply and an output short-circuit protection circuit thereof, which address the above-mentioned drawbacks of the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: an output short-circuit protection circuit of a drive power supply is configured, including: the device comprises a voltage sampling circuit, a comparison circuit and a current reference regulating circuit; the voltage sampling circuit, the comparison circuit and the current reference regulating circuit are arranged at the output end of the driving power supply;
the input end of the voltage sampling circuit is connected with the output end of the driving power supply, the output end of the voltage sampling circuit is connected with the second input end of the comparison circuit, the first input end of the comparison circuit is connected with reference voltage, the output end of the comparison circuit is connected with the input end of the current reference regulating circuit, and the output end of the current reference regulating circuit is connected with the current reference signal input end of the current control loop;
the voltage sampling circuit is used for sampling the output voltage of the driving power supply and outputting a voltage sampling signal to the comparison circuit;
the comparison circuit compares the voltage sampling signal with the reference voltage and outputs a conducting signal to the current reference regulating circuit when the voltage of the voltage sampling signal is smaller than the reference voltage;
the current reference regulating circuit is conducted according to the conducting signal to reduce the reference current of the current control loop.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the output short-circuit protection circuit further includes: a reference voltage generating circuit;
the input end of the reference voltage generating circuit is connected with a reference voltage, and the output end of the reference voltage generating circuit is connected with the first input end of the comparison circuit.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the voltage sampling circuit includes: a first voltage dividing resistor and a second voltage dividing resistor;
a first end of the first voltage-dividing resistor is connected to an output end of the driving power supply, a second end of the first voltage-dividing resistor is connected to a first end of the second voltage-dividing resistor, a connection end of the second end of the first voltage-dividing resistor and the first end of the second voltage-dividing resistor is connected to a second input end of the comparison circuit, and a second end of the second voltage-dividing resistor is grounded;
the first end of the first voltage-dividing resistor is an input end of the voltage sampling circuit, and a connection end between the second end of the first voltage-dividing resistor and the first end of the second voltage-dividing resistor is an output end of the voltage sampling circuit.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the reference voltage generating circuit includes: a third voltage dividing resistor and a fourth voltage dividing resistor;
a first end of the third voltage-dividing resistor is connected to the reference voltage, a second end of the third voltage-dividing resistor is connected to a first end of the fourth voltage-dividing resistor, a connection end of the second end of the third voltage-dividing resistor and the first end of the fourth voltage-dividing resistor is connected to the first input end of the comparison circuit, and a second end of the fourth voltage-dividing resistor is grounded;
a first end of the third voltage dividing resistor is an input end of the reference voltage generating circuit, and a connection end of a second end of the third voltage dividing resistor and a first end of the fourth voltage dividing resistor is an output end of the reference voltage generating circuit.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the comparison circuit includes: a comparator and a fifth resistor;
a positive input end of the comparator is connected to a second end of the third voltage-dividing resistor and a connection end of a first end of the fourth voltage-dividing resistor, a negative input end of the comparator is connected to a second end of the first voltage-dividing resistor and a connection end of a first end of the second voltage-dividing resistor, an output end of the comparator is connected to an input end of the current reference adjusting circuit, a first end of the fifth resistor is connected to a positive input end of the comparator, and a second end of the fifth resistor is connected to an output end of the comparator;
the positive input end of the comparator is the first input end of the comparison circuit, the negative input end of the comparator is the second input end of the comparison circuit, and the output end of the comparator is the output end of the comparison circuit.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the comparison circuit includes: a comparator, a first diode and a fifth resistor;
a positive input end of the comparator is connected to a second end of the third voltage-dividing resistor and a connection end of a first end of the fourth voltage-dividing resistor, a negative input end of the comparator is connected to a second end of the first voltage-dividing resistor and a connection end of a first end of the second voltage-dividing resistor, an output end of the comparator is connected to an input end of the current reference adjusting circuit, a cathode of the first diode is connected to a positive input end of the comparator, an anode of the first diode is connected to a first end of the fifth resistor, and a second end of the fifth resistor is connected to an output end of the comparator;
the positive input end of the comparator is the first input end of the comparison circuit, the negative input end of the comparator is the second input end of the comparison circuit, and the output end of the comparator is the output end of the comparison circuit.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the current reference adjusting circuit includes: the sixth resistor, the seventh resistor, the eighth resistor, the ninth resistor and the switching tube;
a first end of the sixth resistor is connected with an output end of the comparator, a second end of the sixth resistor is connected with a first end of the seventh resistor and a first end of the switching tube, a first end of the eighth resistor is connected with a reference signal, a second end of the eighth resistor is connected with a first end of the ninth resistor, a second end of the ninth resistor is connected with a second end of the switching tube, a third end of the switching tube and a second end of the seventh resistor are grounded, and a connection end of the second end of the eighth resistor and the first end of the ninth resistor is further connected to a current reference signal input end of the current control loop;
the first end of the sixth resistor is an input end of the current reference regulating circuit, and a connection end between the second end of the eighth resistor and the first end of the ninth resistor is an output end of the current reference regulating circuit.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the current reference adjusting circuit includes: a sixth resistor and an eighth resistor;
a first end of the sixth resistor is connected with the output end of the comparator, a second end of the sixth resistor is connected with a second end of the eighth resistor, the first end of the eighth resistor is connected with a reference signal, and a connection end of the second end of the sixth resistor and the second end of the eighth resistor is further connected with a current reference signal input end of the current control loop;
the first end of the sixth resistor is the input end of the current reference regulating circuit, and the connection end of the second end of the sixth resistor and the second end of the eighth resistor is the output end of the current reference regulating circuit.
In the output short-circuit protection circuit of a driving power supply according to the present invention, the current reference adjusting circuit includes: a second diode, a sixth resistor and an eighth resistor;
a cathode of the second diode is connected with an output end of the comparator, an anode of the second diode is connected with a second end of the sixth resistor, a first end of the sixth resistor is connected with a second end of the eighth resistor, the first end of the eighth resistor is connected with a reference signal, and a connection end of the first end of the sixth resistor and the second end of the eighth resistor is further connected to a current reference signal input end of the current control loop;
the cathode of the second diode is an input end of the current reference regulating circuit, and a connection end of a first end of the sixth resistor and a second end of the eighth resistor is an output end of the current reference regulating circuit.
The present invention also provides a driving power supply including: the output short-circuit protection circuit of the driving power supply.
The output short-circuit protection circuit of the driving power supply has the following beneficial effects: the device comprises a voltage sampling circuit, a comparison circuit and a current reference regulating circuit; the input end of the voltage sampling circuit is connected with the output end of the driving power supply, the output end of the voltage sampling circuit is connected with the second input end of the comparison circuit, the first input end of the comparison circuit is connected with reference voltage, the output end of the comparison circuit is connected with the input end of the current reference regulating circuit, and the output end of the current reference regulating circuit is connected to the current reference signal input end of the current control loop; the voltage sampling circuit samples the output voltage of the driving power supply and outputs a voltage sampling signal; the comparison circuit compares the voltage sampling signal with a reference voltage and outputs a conducting signal when the voltage of the voltage sampling signal is smaller than the reference voltage; the current reference regulating circuit is conducted according to the conducting signal to reduce the reference current. This practicality is through discerning the short circuit and reducing reference current at power secondary side, avoids the circuit out of control, effective protection circuit and power.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
fig. 1 is a schematic block diagram of an output short-circuit protection circuit of a driving power supply according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a first embodiment of an output short-circuit protection circuit of a driving power supply according to the present invention;
FIG. 3 is a circuit diagram of a second embodiment of the output short-circuit protection circuit of the driving power supply according to the present invention;
fig. 4 is a circuit diagram of a third embodiment of an output short-circuit protection circuit of a driving power supply according to the present invention;
fig. 5 is a circuit diagram of a fourth embodiment of the output short-circuit protection circuit of the driving power supply according to the present invention;
fig. 6 is a circuit diagram of an embodiment of an output short-circuit protection circuit of a driving power supply according to the present invention;
fig. 7 is a circuit diagram of an output short-circuit protection circuit of a driving power supply according to a sixth embodiment of the present invention;
fig. 8 is a circuit diagram of a seventh embodiment of the output short-circuit protection circuit of the driving power supply provided by the present invention;
fig. 9 is a circuit diagram of an embodiment eight of the output short-circuit protection circuit of the driving power supply provided by the present invention;
fig. 10 is a schematic diagram of an output current of the output short-circuit protection circuit of the driving power supply according to the present invention.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
Referring to fig. 1, fig. 1 is a schematic block diagram of an alternative embodiment of an output short-circuit protection circuit of a driving power supply provided by the present invention. This output short-circuit protection circuit sets up the output at drive power supply, be used for carrying out real-time sampling to drive power supply's output voltage, and carry out the comparison with voltage sampling signal that real-time sampling obtained, when voltage sampling signal is less than reference voltage, judge that drive power supply's output appears the short circuit promptly, and then directly reduce current control loop's reference current, realize drawing down output current immediately when the output short circuit, reduce output, reach the purpose of protection, can also avoid appearing the electric current spike simultaneously once, avoid appearing the circuit out of control phenomenon and lead to device and power damage in the circuit, effective protection circuit and power.
Specifically, as shown in fig. 1, the output short-circuit protection circuit of the driving power supply includes: a voltage sampling circuit 101, a comparison circuit 103, and a current reference adjustment circuit 104; the voltage sampling circuit 101, the comparison circuit 103, and the current reference adjustment circuit 104 are provided at the output terminal of the drive power supply.
The input end of the voltage sampling circuit 101 is connected with the output end of the driving power supply, the output end of the voltage sampling circuit 101 is connected with the second input end of the comparison circuit 103, the first input end of the comparison circuit 103 is connected with reference voltage, the output end of the comparison circuit 103 is connected with the input end of the current reference regulating circuit 104, and the output end of the current reference regulating circuit 104 is connected with the current reference signal input end of the current control loop.
The voltage sampling circuit 101 is configured to sample an output voltage of the driving power supply and output a voltage sampling signal to the comparison circuit 103.
Optionally, in some embodiments, the voltage sampling circuit 101 may be implemented by dividing voltage through resistors, that is, by connecting a plurality of resistors in series, sampling the voltage output by the output terminal of the driving power supply in real time, and dividing the voltage output by the resistors to obtain a voltage sampling signal.
The comparison circuit 103 compares the voltage sampling signal with a reference voltage, and outputs a turn-on signal to the current reference adjustment circuit 104 when the voltage of the voltage sampling signal is smaller than the reference voltage.
Alternatively, in some embodiments, the comparison circuit 103 may be implemented by the comparator U1A or a conventional operational amplifier. The comparator U1A may be an OC type comparator U1A.
The current reference regulating circuit 104 is turned on according to the on signal to reduce the reference current of the current control loop. The current control loop is a reference current of the secondary side, directly reduces the power of the secondary side and avoids the impact current of the primary side.
Optionally, in some embodiments, the current reference adjusting circuit 104 may be implemented by dividing voltage through a switch tube Q1 and a resistor, where the switch tube Q1 may be a field effect transistor or a bipolar transistor. Of course, it is understood that, in other embodiments, the switch tube Q1 may be replaced by a pull-down or pull-up function implemented in the output pin of the comparator U1A. Alternatively, in some other embodiments, the diode is added to the output pin of the comparator U1A to realize the pull-down only and not the pull-up.
Further, in some embodiments, as shown in fig. 1, the output short-circuit protection circuit of the driving power supply further includes: the reference voltage generating circuit 102.
An input terminal of the reference voltage generating circuit 102 is connected to a reference voltage, and an output terminal of the reference voltage generating circuit 102 is connected to a first input terminal of the comparing circuit 103.
Optionally, in some embodiments, the reference voltage generating circuit 102 may be implemented by dividing voltage through resistors, that is, by connecting a plurality of resistors in series, dividing the reference voltage to obtain the reference voltage.
The following examples are given for the purpose of illustration.
The first embodiment is as follows:
referring to fig. 2, fig. 2 is a circuit diagram of a first embodiment of an output short-circuit protection circuit of a driving power supply according to the present invention.
As shown in fig. 2, in this embodiment, the voltage sampling circuit 101 includes: a first voltage dividing resistor R1 and a second voltage dividing resistor R2. The reference voltage generating circuit 102 includes: a third voltage dividing resistor R3 and a fourth voltage dividing resistor R4. The comparison circuit 103 includes: a comparator U1A and a fifth resistor R5. The current reference adjusting circuit 104 includes: a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a switching tube Q1. In this embodiment, the switching transistor Q1 is a MOS transistor. The first end of the switching tube Q1 is a grid electrode of the MOS tube, the second end of the switching tube Q1 is a drain electrode of the MOS tube, and the third end of the switching tube Q1 is a source electrode of the MOS tube.
As shown in fig. 2, a first end of the first voltage-dividing resistor R1 is connected to the output end of the driving power supply, a second end of the first voltage-dividing resistor R1 is connected to a first end of the second voltage-dividing resistor R2, a connection end between the second end of the first voltage-dividing resistor R1 and the first end of the second voltage-dividing resistor R2 is connected to a second input end of the comparing circuit 103, and a second end of the second voltage-dividing resistor R2 is grounded. The first end of the first voltage-dividing resistor R1 is an input end of the voltage sampling circuit 101, and a connection end between the second end of the first voltage-dividing resistor R1 and the first end of the second voltage-dividing resistor R2 is an output end of the voltage sampling circuit 101.
The first end of the third voltage-dividing resistor R3 is connected to the reference voltage, the second end of the third voltage-dividing resistor R3 is connected to the first end of the fourth voltage-dividing resistor R4, the connection end of the second end of the third voltage-dividing resistor R3 and the first end of the fourth voltage-dividing resistor R4 is connected to the first input end of the comparison circuit 103, and the second end of the fourth voltage-dividing resistor R4 is grounded. A first end of the third voltage dividing resistor R3 is an input end of the reference voltage generating circuit 102, and a connection end between a second end of the third voltage dividing resistor R3 and a first end of the fourth voltage dividing resistor R4 is an output end of the reference voltage generating circuit 102.
The positive input end of the comparator U1A is connected to the second end of the third voltage-dividing resistor R3 and the connection end of the first end of the fourth voltage-dividing resistor R4, the negative input end of the comparator U1A is connected to the second end of the first voltage-dividing resistor R1 and the connection end of the first end of the second voltage-dividing resistor R2, the output end of the comparator U1A is connected to the input end of the current reference adjusting circuit 104, the first end of the fifth resistor R5 is connected to the positive input end of the comparator U1A, and the second end of the fifth resistor R5 is connected to the output end of the comparator U1A. The positive input end of the comparator U1A is a first input end of the comparison circuit 103, the negative input end of the comparator U1A is a second input end of the comparison circuit 103, and the output end of the comparator U1A is an output end of the comparison circuit 103.
Referring to fig. 3, fig. 3 is a circuit diagram of a second embodiment of the output short-circuit protection circuit of the driving power supply according to the present invention.
As shown in fig. 3, in this embodiment, the structural composition of the voltage sampling circuit 101, the reference voltage generating circuit 102, and the comparing circuit 103 is the same as that of the first embodiment, and only the current reference adjusting circuit 104 is different. In this embodiment, the current reference adjusting circuit 104 includes: a sixth resistor R6 and an eighth resistor R8.
As shown in fig. 3, a first end of the sixth resistor R6 is connected to the output end of the comparator U1A, a second end of the sixth resistor R6 is connected to a second end of the eighth resistor R8, the first end of the eighth resistor R8 is connected to the reference signal, and a connection end of the second end of the sixth resistor R6 and the second end of the eighth resistor R8 is further connected to the current reference signal input end of the current control loop. A first end of the sixth resistor R6 is an input end of the current reference adjusting circuit 104, and a connection end between a second end of the sixth resistor R6 and a second end of the eighth resistor R8 is an output end of the current reference adjusting circuit 104.
In this embodiment, the sixth resistor R6 and the eighth resistor R8 directly form a voltage divider circuit, which further simplifies the output signal control portion and achieves the purpose of adjusting the reference current.
Referring to fig. 4, fig. 4 is a circuit diagram of a third embodiment of the output short-circuit protection circuit of the driving power supply according to the present invention.
As shown in fig. 4, in this embodiment, the structural compositions of the voltage sampling circuit 101, the reference voltage generating circuit 102, and the current reference adjusting circuit 104 are the same as those of the embodiment, and only the comparison circuit 103 is different. In this embodiment, the comparison circuit 103 includes: comparator U1A, the first diode and fifth resistance R5.
As shown in fig. 4, a positive input end of the comparator U1A is connected to the second end of the third voltage-dividing resistor R3 and the connection end of the first end of the fourth voltage-dividing resistor R4, a negative input end of the comparator U1A is connected to the second end of the first voltage-dividing resistor R1 and the connection end of the first end of the second voltage-dividing resistor R2, an output end of the comparator U1A is connected to the input end of the current reference adjusting circuit 104, a cathode of the first diode D1 is connected to the positive input end of the comparator U1A, an anode of the first diode D1 is connected to the first end of the fifth resistor R5, and a second end of the fifth resistor R5 is connected to the output end of the comparator U1A. The positive input end of the comparator U1A is a first input end of the comparison circuit 103, the negative input end of the comparator U1A is a second input end of the comparison circuit 103, and the output end of the comparator U1A is an output end of the comparison circuit 103.
In this embodiment, on the basis of the second embodiment, the first diode D1 is added, so that the working quadrant and the hysteresis range of the comparator U1A can be adjusted.
Referring to fig. 5, fig. 5 is a circuit diagram of a fourth embodiment of the output short-circuit protection circuit of the driving power supply according to the present invention.
As shown in fig. 5, in this embodiment, the structural composition of the voltage sampling circuit 101, the reference voltage generating circuit 102, and the current reference adjusting circuit 104 is the same as that of the first embodiment, and only the comparison circuit 103 is different. In this embodiment, the comparison circuit 103 includes: comparator U1A, the first diode and fifth resistance R5.
As shown in fig. 5, the positive input terminal of the comparator U1A is connected to the second terminal of the third voltage-dividing resistor R3 and the first terminal of the fourth voltage-dividing resistor R4, the negative input terminal of the comparator U1A is connected to the second terminal of the first voltage-dividing resistor R1 and the first terminal of the second voltage-dividing resistor R2, the output terminal of the comparator U1A is connected to the input terminal of the current reference adjusting circuit 104, the cathode of the first diode D1 is connected to the positive input terminal of the comparator U1A, the anode of the first diode D1 is connected to the first terminal of the fifth resistor R5, and the second terminal of the fifth resistor R5 is connected to the output terminal of the comparator U1A. The positive input end of the comparator U1A is a first input end of the comparison circuit 103, the negative input end of the comparator U1A is a second input end of the comparison circuit 103, and the output end of the comparator U1A is an output end of the comparison circuit 103.
Referring to fig. 6, fig. 6 is a circuit diagram of an output short-circuit protection circuit of a driving power supply according to a fifth embodiment of the present invention.
As shown in fig. 6, in this embodiment, the structural compositions of the voltage sampling circuit 101, the reference voltage generating circuit 102, and the comparing circuit 103 are the same as those of the first embodiment, and only the current reference adjusting circuit 104 is different. In this embodiment, the comparison circuit 103 is different from the comparison circuit 103 of the first embodiment in that the switching transistor Q1 in this embodiment is a triode. In this embodiment, the first end of the switching tube Q1 is a base of the triode, the second end of the switching tube Q1 is a collector of the triode, and the third end of the switching tube Q1 is an emitter of the triode.
Referring to fig. 7, fig. 7 is a circuit diagram of an output short-circuit protection circuit of a driving power supply according to a sixth embodiment of the present invention.
As shown in fig. 7, in this embodiment, the structural compositions of the voltage sampling circuit 101, the reference voltage generating circuit 102, and the current reference adjusting circuit 104 are the same as those of the fifth embodiment, and only the comparison circuit 103 is different. In this embodiment, the comparison circuit 103 includes: comparator U1A, the first diode and fifth resistance R5.
As shown in fig. 7, a positive input end of the comparator U1A is connected to the second end of the third voltage-dividing resistor R3 and the connection end of the first end of the fourth voltage-dividing resistor R4, a negative input end of the comparator U1A is connected to the second end of the first voltage-dividing resistor R1 and the connection end of the first end of the second voltage-dividing resistor R2, an output end of the comparator U1A is connected to the input end of the current reference adjusting circuit 104, a cathode of the first diode D1 is connected to the positive input end of the comparator U1A, an anode of the first diode D1 is connected to the first end of the fifth resistor R5, and a second end of the fifth resistor R5 is connected to the output end of the comparator U1A. A positive input end of the comparator U1A is a first input end of the comparator 103, a negative input end of the comparator U1A is a second input end of the comparator 103, and an output end of the comparator U1A is an output end of the comparator 103.
Referring to fig. 8, fig. 8 is a circuit diagram of a seventh embodiment of the output short-circuit protection circuit of the driving power supply according to the present invention.
As shown in fig. 8, in this embodiment, the structural composition of the voltage sampling circuit 101, the reference voltage generating circuit 102, and the comparison circuit 103 are the same as those of the three phases of the embodiment, and only the current reference adjusting circuit 104 is different. In this embodiment, the current reference adjusting circuit 104 includes: a second diode D2, a sixth resistor R6 and an eighth resistor R8.
The cathode of the second diode D2 is connected to the output end of the comparator U1A, the anode of the second diode D2 is connected to the second end of the sixth resistor R6, the first end of the sixth resistor R6 is connected to the second end of the eighth resistor R8, the first end of the eighth resistor R8 is connected to the reference signal, and the connection end of the first end of the sixth resistor R6 and the second end of the eighth resistor R8 is further connected to the current reference signal input end of the current control loop. The cathode of the second diode D2 is an input terminal of the current reference adjusting circuit 104, and a connection end between the first end of the sixth resistor R6 and the second end of the eighth resistor R8 is an output terminal of the current reference adjusting circuit 104.
Referring to fig. 9, fig. 9 is a circuit diagram of an eighth embodiment of the output short-circuit protection circuit of the driving power supply according to the present invention.
As shown in fig. 9, in this embodiment, the constituent structures of the voltage sampling circuit 101, the reference voltage generating circuit 102, and the current reference adjusting circuit 104 are the same as those of the seventh embodiment, and only the comparison circuit 103 is different. In this embodiment, the comparison circuit 103 includes: a comparator U1A and a fifth resistor R5.
As shown in fig. 9, a positive input end of the comparator U1A is connected to the second end of the third voltage-dividing resistor R3 and the connection end of the first end of the fourth voltage-dividing resistor R4, a negative input end of the comparator U1A is connected to the second end of the first voltage-dividing resistor R1 and the connection end of the first end of the second voltage-dividing resistor R2, an output end of the comparator U1A is connected to an input end of the current reference adjusting circuit 104 (i.e., a cathode of the second diode D2), a first end of the fifth resistor R5 is connected to the positive input end of the comparator U1A, and a second end of the fifth resistor R5 is connected to the output end of the comparator U1A. The positive input end of the comparator U1A is a first input end of the comparison circuit 103, the negative input end of the comparator U1A is a second input end of the comparison circuit 103, and the output end of the comparator U1A is an output end of the comparison circuit 103.
By adding a second diode D2, a different tuning range can be achieved.
Further, the present invention also provides a driving power supply, including: the embodiment of the invention provides an output short-circuit protection circuit of a driving power supply. The driving power supply comprises but is not limited to an LED driving power supply, and can be applied to the fields of LED illumination, LED display, LED backlight and the like.
As shown in fig. 2, VO + is an equivalent output voltage end, and the first voltage dividing resistor R1 and the second voltage dividing resistor R2 form a voltage sampling circuit 101, divide the output voltage according to a certain proportion, and send the divided voltage to an input end of the comparator U1A; VREF is a stable voltage source, and the third voltage dividing resistor R3 and the fourth voltage dividing resistor R4 form a reference voltage generating circuit 102, which is set at a protection reference point required in the circuit; the fifth resistor R5 and the comparator U1A form a positive feedback circuit of the comparator U1A, a hysteresis control effect is achieved, and misoperation or output jitter of the circuit is effectively avoided; when the trigger condition is met (the voltage of the negative input end of the comparator U1A (the voltage of the voltage sampling signal) is smaller than the voltage of the positive input end of the comparator U1A (the reference voltage)), the output signal (the high-level signal) drives the switching tube Q1 to be conducted through the sixth resistor R6 and the seventh resistor R7, the ninth resistor R9 enters a working state, and the ninth resistor R9 and the eighth resistor R8 form a voltage division circuit to divide voltage of IREF, so that a proper I-ref signal is obtained, and the I-ref signal is a constant current reference for normal working of the circuit. Because the current reference is divided by the voltage and is necessarily reduced, the actual output current of the power supply is reduced, and therefore the protection effect is achieved. The specific operating current of the circuit is schematically shown in fig. 10.
As can be seen from fig. 10, when the output terminal is short-circuited, the current in the circuit can be rapidly pulled down, so as to achieve the purpose of effectively protecting the circuit and driving the power supply.
The above embodiments are only for illustrating the technical idea and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.

Claims (7)

1. An output short-circuit protection circuit of a driving power supply, comprising: the device comprises a voltage sampling circuit, a comparison circuit and a current reference regulating circuit; the voltage sampling circuit, the comparison circuit and the current reference regulating circuit are arranged at the output end of the driving power supply;
the input end of the voltage sampling circuit is connected with the output end of the driving power supply, the output end of the voltage sampling circuit is connected with the second input end of the comparison circuit, the first input end of the comparison circuit is connected with reference voltage, the output end of the comparison circuit is connected with the input end of the current reference regulating circuit, and the output end of the current reference regulating circuit is connected to the current reference signal input end of the current control loop;
the voltage sampling circuit is used for sampling the output voltage of the driving power supply and outputting a voltage sampling signal to the comparison circuit;
the comparison circuit compares the voltage sampling signal with the reference voltage and outputs a conducting signal to the current reference regulating circuit when the voltage of the voltage sampling signal is smaller than the reference voltage;
the current reference regulating circuit is conducted according to the conducting signal to reduce the reference current of the current control loop;
the current reference regulating circuit includes: the sixth resistor, the seventh resistor, the eighth resistor, the ninth resistor and the switching tube;
a first end of the sixth resistor is connected to an output end of the comparison circuit, a second end of the sixth resistor is connected to a first end of the seventh resistor and a first end of the switching tube, a first end of the eighth resistor is connected to a reference signal, a second end of the eighth resistor is connected to a first end of the ninth resistor, a second end of the ninth resistor is connected to a second end of the switching tube, a third end of the switching tube and a second end of the seventh resistor are grounded, and a connection end of the second end of the eighth resistor and the first end of the ninth resistor is further connected to a current reference signal input end of the current control loop;
the first end of the sixth resistor is the input end of the current reference regulating circuit, and the connection end of the second end of the eighth resistor and the first end of the ninth resistor is the output end of the current reference regulating circuit.
2. The output short-circuit protection circuit of a driving power supply according to claim 1, further comprising: a reference voltage generating circuit;
the input end of the reference voltage generating circuit is connected with a reference voltage, and the output end of the reference voltage generating circuit is connected with the first input end of the comparison circuit.
3. The output short-circuit protection circuit of a driving power supply according to claim 2, wherein the voltage sampling circuit comprises: a first voltage dividing resistor and a second voltage dividing resistor;
a first end of the first voltage-dividing resistor is connected with an output end of the driving power supply, a second end of the first voltage-dividing resistor is connected with a first end of the second voltage-dividing resistor, a connection end of the second end of the first voltage-dividing resistor and the first end of the second voltage-dividing resistor is connected to a second input end of the comparison circuit, and a second end of the second voltage-dividing resistor is grounded;
the first end of the first voltage-dividing resistor is an input end of the voltage sampling circuit, and a connection end between the second end of the first voltage-dividing resistor and the first end of the second voltage-dividing resistor is an output end of the voltage sampling circuit.
4. The output short-circuit protection circuit of claim 3, wherein the reference voltage generation circuit comprises: a third voltage dividing resistor and a fourth voltage dividing resistor;
a first end of the third voltage-dividing resistor is connected to the reference voltage, a second end of the third voltage-dividing resistor is connected to a first end of the fourth voltage-dividing resistor, a connection end of the second end of the third voltage-dividing resistor and the first end of the fourth voltage-dividing resistor is connected to the first input end of the comparison circuit, and a second end of the fourth voltage-dividing resistor is grounded;
a first end of the third voltage dividing resistor is an input end of the reference voltage generating circuit, and a connection end of a second end of the third voltage dividing resistor and a first end of the fourth voltage dividing resistor is an output end of the reference voltage generating circuit.
5. The output short-circuit protection circuit of a driving power supply according to claim 4, wherein the comparison circuit includes: a comparator and a fifth resistor;
a positive input end of the comparator is connected to a second end of the third voltage-dividing resistor and a first end of the fourth voltage-dividing resistor, a negative input end of the comparator is connected to a second end of the first voltage-dividing resistor and a first end of the second voltage-dividing resistor, an output end of the comparator is connected to a first end of the sixth resistor, a first end of the fifth resistor is connected to a positive input end of the comparator, and a second end of the fifth resistor is connected to an output end of the comparator;
the positive input end of the comparator is the first input end of the comparison circuit, the negative input end of the comparator is the second input end of the comparison circuit, and the output end of the comparator is the output end of the comparison circuit.
6. The output short-circuit protection circuit of a driving power supply according to claim 4, wherein the comparison circuit includes: the comparator, the first diode and the fifth resistor;
a positive input end of the comparator is connected to a second end of the third voltage-dividing resistor and a first end of the fourth voltage-dividing resistor, a negative input end of the comparator is connected to a second end of the first voltage-dividing resistor and a first end of the second voltage-dividing resistor, an output end of the comparator is connected to a first end of the sixth resistor, a cathode of the first diode is connected to a positive input end of the comparator, an anode of the first diode is connected to a first end of the fifth resistor, and a second end of the fifth resistor is connected to an output end of the comparator;
the positive input end of the comparator is the first input end of the comparison circuit, the negative input end of the comparator is the second input end of the comparison circuit, and the output end of the comparator is the output end of the comparison circuit.
7. A drive power supply, comprising: an output short-circuit protection circuit of a driving power supply according to any one of claims 1 to 6.
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