CN210867178U

CN210867178U - Driver short-circuit protection circuit

Info

Publication number: CN210867178U
Application number: CN201921709458.9U
Authority: CN
Inventors: 林延军
Original assignee: Zhejiang kaiyao Lighting Co Ltd
Current assignee: Zhejiang kaiyao Lighting Co Ltd
Priority date: 2019-10-12
Filing date: 2019-10-12
Publication date: 2020-06-26
Anticipated expiration: 2029-10-12

Abstract

The utility model discloses a driver short-circuit protection circuit. The protection circuit aims to overcome the problem that a protection circuit cannot keep a short-circuit protection state all the time after a driver is short-circuited and loses power. The utility model adopts the structure that the short-circuit protection circuit comprises a voltage transformation module, a rectification module, a filtering module, a driving module and an output module which are connected in sequence, the short-circuit protection circuit also comprises a detection module and a protection module, the detection end of the detection module is connected with the output module, the output end of the detection module is connected with the input end of the protection module, and the output end of the protection module is connected with the driving module; the protection module comprises an element which is used for continuously supplying power to the protection module during short-circuit protection. After the short-circuit protection action is executed and the power is lost, the protection module can be maintained to carry out the short-circuit protection continuously by depending on the power supply of the capacitor. After short circuit loses the electricity, increase forward power supply circuit in the output module, ensure that detection module can maintain short circuit detection state after the short circuit loses the electricity always, improved the security of circuit.

Description

Driver short-circuit protection circuit

Technical Field

The utility model relates to a short-circuit protection field especially relates to a driver short-circuit protection circuit.

Background

With the vigorous popularization of energy-saving products in China, the demand of a DC power supply and an LED driver on the market is increasing. Under various demand changes, power and LED driver certification and safety requirements are increasing. After the output is short-circuited, a very high current is generated on a loop, and if a driver is not protected, a power device or an external lead in the loop generates high loss, so that the reliability and safety risk of a product are influenced due to heating. And most products only enter into the protective state when the short circuit on the output terminal, and when the output lead wire is longer, have certain internal resistance, cause the preceding stage to discern not short-circuit protection, can output power continuously, and output stage detection loop, because the output short circuit loses the power supply support, can't give the short-circuit protection signal.

For example, a "PWM output short-circuit protection circuit" disclosed in chinese patent literature, whose publication number "CN 103490391B" includes an input port, an output port, an MCU chip, and a switching tube, where the input port is connected to the output port by connecting a lead inductor, the MUC chip has a PWM output pin, the PWM output pin is connected to a control terminal of the switching tube, one end of the switching tube is connected to the output port, and the other end is grounded, a voltage dividing line is connected between the output port and the ground, the MCU chip further has an external interrupt pin, and the external interrupt pin is connected to the voltage dividing line. The short circuit mode can only act at the moment of short circuit, after the short circuit protection action, the power is cut off due to the fact that short circuit protection is carried out after the protection signal is received again, and the protection circuit cannot execute the protection action; the short-circuit protection cannot be carried out for a long time, and the short-circuit protection state cannot be kept all the time during short circuit.

SUMMERY OF THE UTILITY MODEL

The utility model mainly solves the problem that the protection circuit can not keep the short-circuit protection state all the time after the driver is short-circuited and loses power in the prior art; a driver short-circuit protection circuit is provided, which can maintain a short-circuit protection state after a driver is short-circuited and loses power.

The above technical problem of the present invention can be solved by the following technical solutions:

the utility model comprises a voltage transformation module, a rectification module, a filtering module, a driving module and an output module which are connected in sequence, wherein the short-circuit protection circuit also comprises a detection module and a protection module, the detection end of the detection module is connected with the output module, the output end of the detection module is connected with the input end of the protection module, and the output end of the protection module is connected with the driving module; the protection module comprises an element which is used for continuously supplying power to the protection module during short-circuit protection. The detection module is connected with the output module, detects whether the output is short-circuited, and sends a short-circuit signal to the protection module when the output is short-circuited, and the protection module performs short-circuit protection on the driving module and disconnects the power supply of the driving module. The continuous power supply element during short-circuit protection is added in the protection module, after the protection module performs short-circuit protection action to power off the driver, if the detection module continues to detect a short-circuit signal, the protection module continues to power off the drive module, the short-circuit protection action can be kept all the time, and the chip power supply loop cannot be restored to continue short circuit due to charging. The safety of the driver short-circuit protection circuit is improved, and the service life of the circuit is prolonged.

Preferably, the protection module comprises an optocoupler U42, a diode DS61, a diode DS6, a resistor RS63, a resistor RS64, a resistor RS59A, a resistor RS59B, a transistor QS62, a transistor QS63, a capacitor CS64 and an electrolytic capacitor C63; two ends of a diode of the optical coupler U42 are connected with the detection module, a collector of the optical coupler U42 is connected with a power supply end of the driving module, an emitter of the optical coupler U42 is connected with a first end of a resistor RS59A, a second end of the resistor RS59A is connected with a first end of a resistor RS59B, and a second end of the resistor RS59 is grounded; the positive terminal of the electrolytic capacitor C63 is connected with the first terminal of the resistor RS59B, and the negative terminal of the electrolytic capacitor C63 is grounded; the base electrode of the triode QS62 is connected with the positive electrode end of the electrolytic capacitor C63, the emitter electrode of the triode QS62 is grounded, the collector electrode of the triode QS62 is connected with the base electrode of the triode QS63, the emitter electrode of the triode QS63 is connected with the power supply end of the driving module, the collector electrode of the triode QS is connected with the first end of the resistor RS64, and the second end of the resistor RS64 is connected with the base electrode of the triode QS 63; the anode of the diode DS63 is connected with the emitter of the transistor QS63, and the cathode of the diode DS63 is connected with the base of the transistor QS 63; the first end of the capacitor CS64 is connected to the collector of the transistor QS63, the second end of the capacitor CS64 is grounded, the first end of the resistor RS63 is connected to the first end of the resistor RS64, the second end of the resistor RS63 is connected to the cathode of the diode DS61, and the anode of the diode DS61 is connected to the feedback end of the driving module. When the detection module detects a short-circuit signal, the optocoupler U42 is switched on, so that the triode QS62 is switched on, the power supply end of the driving module is directly grounded, and the driving module is powered off. The safety of the circuit is improved, the power supply cutting speed is high, and the optical coupler U42 is used for preventing the interference of voltage jitter.

Preferably, the elements for continuously supplying power to the protection module 7 are a diode DS62 and a capacitor CS 65; a first end of the capacitor CS65 is connected with a collector of the optocoupler U42, and a second end of the capacitor CS65 is grounded; the cathode of the diode DS62 is connected to the first terminal of the capacitor CS65, and the anode of the diode DS62 is connected to the power supply terminal of the driving module. The power supply of the optocoupler U42 depends on the power supply end of the driving module to supply power together, and when the power supply end of the driving module is grounded by the protection module, the power supply of the driving module is disconnected, and meanwhile, the power supply of the optocoupler U42 is also disconnected. The driving module can quickly restore self-charging through the chip power supply loop. After the diode DS62 and the capacitor CS65 are added, the capacitor CS65 is normally charged, after the power supply of the driver is disconnected, the capacitor CS65 is used for supplying power to the optocoupler U42, and the unidirectional conduction characteristic of the diode DS62 enables the electric energy in the capacitor CS65 to supply power only to the optocoupler U42, and does not flow to the driving module. After the short-circuit action driver is powered off, the short-circuit protection function can be maintained all the time, and when a next short-circuit signal is obtained, the short-circuit protection action can be still carried out, so that the safety of the circuit is improved.

Preferably, the detection module comprises a resistor R51, a resistor RS52A, a resistor RS53A, a resistor RS53B, a resistor RS53D, a resistor RS58, a capacitor CS55, a capacitor CS51, a capacitor CS53, a diode DS51A, a voltage regulator ZS51 and a comparator US 51; the two ends of the resistor R51 are connected with the output module, the first end of the capacitor CS55 is connected with the first end of the resistor R51, the second end of the capacitor CS55 is connected with the second end of the resistor R51, the second end of the resistor R51 is connected with the first end of the resistor RS52A, the second end of the resistor RS52A is connected with the first end of the capacitor CS51, and the second end of the capacitor CS51 is grounded; the positive input end of the comparator US51 is connected with the second end of the resistor RS52A, the output end of the comparator US51 is connected with the anode of the diode DS51A, the cathode of the diode DS51A is connected with the first end of the resistor RS58, and the second end of the resistor RS58 is connected with the protection module; a first end of the capacitor CS52 is connected with the output end of the comparator US51, and a second end of the capacitor CS52 is connected with the negative input end of the comparator US 51; the negative input end of the comparator US51 is connected with the first end of the resistor RS53B, the first end of the resistor RS53D is connected with the negative input end of the comparator US51, and the second end of the resistor RS53D is grounded; the second end of the resistor RS53B is connected with the cathode of the voltage regulator ZS51, the anode of the voltage regulator ZS51 is grounded, the cathode of the voltage regulator ZS51 is connected with the first end of the capacitor CS53, and the second end of the capacitor CS53 is grounded; a first terminal of the resistor RS53A is connected to the output terminal of the output module, and a second terminal of the resistor RS53A is connected to a first terminal of the capacitor CS 53. When the output end of the output module is short-circuited, the voltage of the current detection resistor R51 is raised, the voltage is input from the positive output end of the comparator US51 and is compared with the reference voltage of the negative input end of the comparator US51, when the voltage of the positive input end exceeds 0.125V, the operational amplifier outputs high level, and the sink current is limited to a high level signal of the protection module through the diode DS51A and the resistor RS 58. The short-circuit signal can be accurately sent, the circuit is simple, and the safety of the circuit is improved.

Preferably, the output module comprises a forward power supply loop for supplying power to the comparator US 51; the forward power supply loop comprises a transformer L41, a diode DS53 and an electrolytic capacitor C56; a primary side L41A of the transformer L41 is an output end of the driving module, a first secondary side L41C of the transformer L41 is an input end of the output module, a first end of a second secondary side L41D of the transformer L41 is connected with a first secondary side L41C of the transformer L41, a second end of a second secondary side L41D of the transformer L41 is connected with an anode of a diode DS53, a cathode of the diode DS53 is connected with a positive end of an electrolytic capacitor C56, and a negative end of the electrolytic capacitor C56 is grounded; the positive terminal of the electrolytic capacitor C56 is connected with the power supply terminal of the comparator US 51. Because the voltage of the short-circuit output is jumped between 0V and 5V, the power supply for the detection loop operational amplifier cannot be provided, and the detection loop cannot transmit the over-current protection information to the front stage. A forward power supply loop is added, when power is supplied normally, the electrolytic capacitor C56 is charged through the diode DS53 through the second secondary side L41D of the transformer L41, and the comparator US51 supplies power through the diode DS54 through the output 24V voltage of the output module; when the output is short-circuited, the electrolytic capacitor C56 supplies power to the comparator US51, so that the comparator US51 can be ensured to work normally, and the short-circuit state of the circuit is judged. The power supply for the detection module can be guaranteed under the condition of short circuit power loss, the short circuit state is detected, and short circuit protection is achieved.

Preferably, the driving module comprises a driving chip and a peripheral loop connected with the driving chip, wherein the peripheral loop comprises a chip power supply loop, a voltage feedback loop, a chip output loop and a current feedback loop; the input end of the chip power supply loop is connected with the output end of the filtering module, and the output end of the chip power supply loop is connected with the protection module; the input end of the chip output loop is connected with the output end of the filtering module, and the output end of the chip output loop is connected with the output module. The model of the driving chip is IW3627, the chip power supply loop supplies power to the driving chip, the protection module is connected with the chip power supply loop, and when a short-circuit signal exists, the chip power supply loop is grounded, so that the driving module is powered off to perform short-circuit protection action.

Preferably, the chip power supply circuit comprises a resistor RS61, a resistor RS62, a capacitor CS62, an electrolytic capacitor C61 and a MOS transistor QS 61; a first end of the resistor RS61 is connected with an output end of the filtering module, a second end of the resistor RS61 is connected with a gate of the MOS transistor QS61, a first end of the resistor RS62 is connected with a first end of the resistor RS61, and a second end of the resistor RS62 is connected with a drain of the MOS transistor QS 61; the source of the MOS transistor QS61 is connected with the first end of the capacitor CS62, the second end of the capacitor CS62 is grounded, the first end of the capacitor CS62 is connected with the positive electrode end of the electrolytic capacitor C61, and the second end of the electrolytic capacitor C61 is grounded; the source of the MOS transistor QS61 is connected to the power supply end of the driver chip, the source of the MOS transistor is connected to the protection circuit, and the second end of the resistor RS61 is connected to the high-voltage starting end of the driver chip. When the driving circuit works normally, the chip power supply loop charges a high-voltage starting end VIN of the driving chip through a resistor RS61, controls a MOS tube QS61 to charge VCC of the driving chip through RS62, and when the voltage reaches a starting 14V voltage, the driving chip starts to work and drives a MOS tube Q41 to conduct and output. When the short circuit occurs, the chip power supply loop is grounded by the protection module, the driving chip loses power, and the whole driver executes short circuit protection action to cut off power.

The utility model has the advantages that:

1. the mode of optical coupler power supply in the protection module relies on the electric capacity power supply after carrying out short-circuit protection action and losing power, maintains that the protection module can last short-circuit protection, improves the security of circuit.

2. After short circuit loses the electricity, increase forward power supply circuit in the output module, ensure that comparator US51 can work always, can maintain short circuit detection state always after the short circuit loses the electricity, improved the security of circuit.

Drawings

Fig. 1 is a block diagram of a circuit principle connection structure of the present invention.

Fig. 2 is a circuit diagram of a transforming, rectifying and filtering module according to the present invention.

Fig. 3 is a circuit diagram of a driving module according to the present invention.

Fig. 4 is a circuit diagram of a protection module according to the present invention.

Fig. 5 is a circuit diagram of an output module according to the present invention.

Fig. 6 is a circuit diagram of a detection module according to the present invention.

In the figure, 1, a transformation module, 2, a rectification module, 3, a filtering module, 4, a driving module, 41, a driving chip, 42, a chip power supply loop, 43, a chip output loop, 44, a voltage feedback loop, 45, a current feedback loop, 5, an output module, 6, a detection module and 7, a protection module are arranged.

Detailed Description

The technical solution of the present invention is further specifically described below by way of examples and with reference to the accompanying drawings.

Example (b):

a driver short-circuit protection circuit is shown in figure 1 and comprises a voltage transformation module 1, a rectification module 2, a filtering module 3, a driving module 4 and an output module 5 which are sequentially connected, and further comprises a detection module 6 and a protection module 7, wherein the detection end of the detection module 6 is connected with the output module 5, the output end of the detection module 6 is connected with the input end of the protection module 7, and the output end of the protection module 7 is connected with the driving module 4.

The driving module 4 includes a driving chip 41 and a peripheral loop connected to the driving chip 41, and the peripheral loop includes a chip power supply loop 42, a voltage feedback loop 44, a chip output loop 43, and a current feedback loop 45. The input end of the chip power supply loop 42 is connected with the output end of the filtering module 3, and the output end of the chip power supply loop 42 is connected with the protection module 7; the input end of the chip output loop 43 is connected with the output end of the filter module 3, and the output end of the chip output loop 43 is connected with the output module 5.

As shown in fig. 3, the driver chip 41 has a model IW 3627.

The chip output circuit 43 includes a resistor RS32A, a resistor RS32B, a resistor RS63, a resistor RS43, a resistor RS44, a resistor R41, a resistor R42, a capacitor C45, a capacitor C46, a diode DS32, a diode D42, a MOS transistor Q41, and a transformer L41. The MOS transistor Q41 is an N-channel MOS transistor. The first end of the resistor RS32B is connected to the 6-pin output end of the driver chip 41, the second end of the resistor RS32B is connected to the first end of the resistor RS63, the first end of the resistor RS32A is connected to the first end of the resistor RS32B, the cathode of the diode DS32 is connected to the second end of the resistor RS32A, and the anode of the diode DS32 is connected to the second end of the resistor RS 32B. The second end of the resistor RS63 is connected with the gate of the MOS transistor Q41, the drain of the MOS transistor Q41 is connected with the first end of the resistor RS44, the second end of the resistor RS44 is connected with the first end of the resistor RS43, the second end of the resistor RS43 is connected with the anode of the diode D42, the cathode of the diode D42 is connected with the first end of the resistor R41, the second end of the resistor R41 is connected with the first end of the resistor R42, and the second end of the resistor R42 is connected with the output end of the filter module 3. The first end of the capacitor C46 is connected with the second end of the resistor RS44, the second end of the capacitor C46 is connected with the source of the MOS transistor Q41, the second end of the resistor R41 is connected with the first end of the capacitor C45, and the second end of the capacitor C45 is connected with the second end of the resistor R42. The first end of the primary side L41A of the transformer L41 is connected with the second end of the capacitor C45, the second end of the primary side L41A of the transformer L41 is connected with the anode of the diode D42, and the first end of the primary side L41A of the transformer L41 is the same-name end.

The current feedback loop 45 includes a resistor RS34A, a resistor RS36, and a capacitor CS 31. The first end of the resistor RS35 is connected to the 4-pin current feedback end of the driver chip 41, the second end of the resistor RS35 is connected to the source of the MOS transistor Q41, the first end of the resistor RS34A is connected to the second end of the resistor RS35, and the second end of the resistor RS34A is grounded. The first end of the capacitor CS31 is connected to the first end of the resistor RS35, and the second end of the resistor CS31 is grounded.

The chip power supply circuit 42 comprises a resistor RS61, a resistor RS62, a capacitor CS62, an electrolytic capacitor C61 and a MOS transistor QS 61. A first end of the resistor RS61 is connected to the output end of the filter module 3, a second end of the resistor RS61 is connected to the gate of the MOS transistor QS61, a first end of the resistor RS62 is connected to a first end of the resistor RS61, and a second end of the resistor RS62 is connected to the drain of the MOS transistor QS 61. The source of the MOS transistor QS61 is connected to the first end of the capacitor CS62, the second end of the capacitor CS62 is grounded, the first end of the capacitor CS62 is connected to the positive terminal of the electrolytic capacitor C61, and the second end of the electrolytic capacitor C61 is grounded. The source of the MOS transistor QS61 is connected to pin 1 of the driver chip 41, i.e., the power supply terminal, the source of the MOS transistor is connected to the protection circuit, and the second terminal of the resistor RS61 is connected to pin 3 of the driver chip 41, i.e., the high voltage start terminal.

The voltage feedback loop 44 includes a resistor RS36B, a resistor RS36C, and a capacitor CS 33. The first end of the resistor RS36B is connected to the 2-pin voltage feedback end of the driver chip 41, the second end of the resistor RS36B is connected to the protection module 7, the first end of the capacitor CS33 is connected to the first end of the resistor RS36B, and the second end of the capacitor CS33 is grounded. A first terminal of the resistor RS36C is connected to a first terminal of the capacitor CS33, and a second terminal of the resistor RS36C is grounded. A second terminal of the resistor RS36C is connected to a first terminal of the third secondary side L41B of the transformer L41, and a second terminal of the third secondary side L41B of the transformer L41 is connected to a second terminal of the resistor RS 36B. The first terminal of the third secondary side L41B of the transformer L41 is a dotted terminal.

As shown in fig. 5, the output module 5 includes a diode D41, a resistor RS44, a capacitor C43, a capacitor CS44, and an electrolytic capacitor C42A. The output module 5 further comprises a forward power supply loop for supplying power to the detection module 6. The forward power supply loop comprises a transformer L41, a diode DS53 and an electrolytic capacitor C56. The primary side L41A of the transformer L41 is the output terminal of the driver module 4, and the first secondary side L41C of the transformer L41 is the input terminal of the output module 5. An anode of the diode D41 is connected to the second terminal of the first secondary L41C of the transformer L41, a first terminal of the capacitor C43 is connected to an anode of the diode D41, a second terminal of the capacitor C43 is connected to a first terminal of the resistor R44, and a second terminal of the resistor R44 is connected to a cathode of the diode D41. A first end of a second secondary side L41D of the transformer L41 is connected to a first end of a first secondary side L41C of the transformer L41, a second end of the second secondary side L41D of the transformer L41 is connected to an anode of a diode DS53, a cathode of the diode DS53 is connected to a positive terminal of an electrolytic capacitor C56, and a negative terminal of the electrolytic capacitor C56 is grounded. The positive terminal of the electrolytic capacitor C56 is connected with the power supply terminal of the detection module 6. The positive terminal of the electrolytic capacitor C42A is connected to the cathode of the diode D41, and the negative terminal of the electrolytic capacitor C42A is connected to the negative terminal of the electrolytic capacitor C56. A first end of the capacitor CS44 is connected to the positive terminal of the electrolytic capacitor C42A, and a second end of the capacitor CS44 is connected to the negative terminal of the electrolytic capacitor CS 44. A first terminal of the capacitor CS44 is connected to the supply terminal of the detection module 6. The first terminal of the first secondary L41C of the transformer L41 is a dotted terminal, and the second terminal of the second secondary L41D of the transformer L41 is a dotted terminal.

As shown in fig. 6, the detection module 6 includes a resistor R51, a resistor RS52A, a resistor RS53A, a resistor RS53B, a resistor RS53D, a resistor RS58, a capacitor CS55, a capacitor CS51, a capacitor CS53, a voltage regulator ZS51, and a comparator US 51. The output module 5 is connected to both ends of the resistor R51, the first end of the resistor R52 is connected to the second end of the capacitor CS44, the first end of the capacitor CS55 is connected to the first end of the resistor R51, and the second end of the capacitor CS55 is connected to the second end of the resistor R51. The second end of the resistor R51 is connected to the first end of the resistor RS52A, the second end of the resistor RS52A is connected to the first end of the capacitor CS51, and the second end of the capacitor CS51 is grounded. The positive input end of the comparator US51 is connected with the second end of the resistor RS52A, the output end of the comparator US51 is connected with the anode of the diode DS51A, the cathode of the diode DS51A is connected with the first end of the resistor RS58, and the second end of the resistor RS58 is connected with the protection module 7; a first end of the capacitor CS52 is connected with the output end of the comparator US51, and a second end of the capacitor CS52 is connected with the negative input end of the comparator US 51; the negative input end of the comparator US51 is connected with the first end of the resistor RS53B, the first end of the resistor RS53D is connected with the negative input end of the comparator US51, and the second end of the resistor RS53D is grounded; the second end of the resistor RS53B is connected with the cathode of the voltage regulator ZS51, the anode of the voltage regulator ZS51 is grounded, the cathode of the voltage regulator ZS51 is connected with the first end of the capacitor CS53, and the second end of the capacitor CS53 is grounded. A first terminal of the resistor RS53A is connected to a first terminal of the capacitor CS44, and a second terminal of the resistor RS53A is connected to a first terminal of the capacitor CS 53.

The power supply of the optocoupler U42 depends on the power supply end of the driving module to supply power together, and when the power supply end of the driving module is grounded by the protection module, the power supply of the driving module is disconnected, and meanwhile, the power supply of the optocoupler U42 is also disconnected. The driving module can quickly restore self-charging through the chip power supply loop. After the diode DS62 and the capacitor CS65 are added, the capacitor CS65 is normally charged, after the power supply of the driver is disconnected, the capacitor CS65 is used for supplying power to the optocoupler U42, and the unidirectional conduction characteristic of the diode DS62 enables the electric energy in the capacitor CS65 to supply power only to the optocoupler U42, and does not flow to the driving module. After the short-circuit action driver is powered off, the short-circuit protection function can be maintained all the time, and when a next short-circuit signal is obtained, the short-circuit protection action can be still carried out, so that the safety of the circuit is improved.

Because the voltage of the short-circuit output is jumped between 0V and 5V, the power supply for the detection loop operational amplifier cannot be provided, and the detection loop cannot transmit the over-current protection information to the front stage. A forward power supply loop is added, when power is supplied normally, the electrolytic capacitor C56 is charged through the diode DS53 through the second secondary side L41D of the transformer L41, and the comparator US51 supplies power through the diode DS54 through the output 24V voltage of the output module; when the output is short-circuited, the electrolytic capacitor C56 supplies power to the comparator US51, so that the comparator US51 can be ensured to work normally, and the short-circuit state of the circuit is judged. The power supply for the detection module can be guaranteed under the condition of short circuit power loss, the short circuit state is detected, and short circuit protection is achieved.

As shown in fig. 4, the protection module 7 includes an optocoupler U42, a diode DS61, a diode DS6, a resistor RS63, a resistor RS64, a resistor RS59A, a resistor RS59B, a transistor QS62, a transistor QS63, a capacitor CS64, an electrolytic capacitor C63, a diode DS62, and a capacitor CS 65. The transistor QS36 is an NPN transistor. The first end of the capacitor CS65 is connected with the collector of the optocoupler U42, and the second end of the capacitor CS65 is grounded. The cathode of the diode DS62 is connected to the first end of the capacitor CS65, and the anode of the diode DS62 is connected to the source of the MOS transistor Q61 of the driver module 4. The anode of the optical coupler U42 is connected with the second end of the resistor RS58, and the cathode of the optical coupler U42 is grounded; the collector of the optical coupler U42 is connected with the cathode of the diode DS62, and the emitter of the optical coupler U42 is connected with the first end of the resistor RS 59A. The second end of the resistor RS59A is connected to the first end of the resistor RS59B, and the second end of the resistor RS59 is grounded. The positive terminal of the electrolytic capacitor C63 is connected to the first terminal of the resistor RS59B, and the negative terminal of the electrolytic capacitor C63 is grounded. The base of the transistor QS62 is connected with the positive electrode end of the electrolytic capacitor C63, the emitter of the transistor QS62 is grounded, the collector of the transistor QS62 is connected with the base of the transistor QS63, the emitter of the transistor QS63 is connected with the power supply end of the driving module 4, the collector of the transistor QS is connected with the first end of the resistor RS64, and the second end of the resistor RS64 is connected with the base of the transistor QS 63. The anode of the diode DS63 is connected to the emitter of the transistor QS63, and the cathode of the diode DS63 is connected to the base of the transistor QS 63. A first end of the capacitor CS64 is connected to a collector of the transistor QS63, a second end of the capacitor CS64 is grounded, a first end of the resistor RS63 is connected to a first end of the resistor RS64, a second end of the resistor RS63 is connected to a cathode of the diode DS61, and an anode of the diode DS61 is connected to a second end of the resistor RS36B of the driving module 4.

When the detection module detects a short-circuit signal, the optocoupler U42 is switched on, so that the triode QS62 is switched on, the power supply end of the driving module is directly grounded, and the driving module is powered off. The safety of the circuit is improved, the power supply cutting speed is high, and the optical coupler U42 is used for preventing the interference of voltage jitter. The power supply of the optocoupler U42 depends on the power supply end of the driving module to supply power together, and when the power supply end of the driving module is grounded by the protection module, the power supply of the driving module is disconnected, and meanwhile, the power supply of the optocoupler U42 is also disconnected. The driving module can quickly restore self-charging through the chip power supply loop. After the diode DS62 and the capacitor CS65 are added, the capacitor CS65 is normally charged, after the power supply of the driver is disconnected, the capacitor CS65 is used for supplying power to the optocoupler U42, and the unidirectional conduction characteristic of the diode DS62 enables the electric energy in the capacitor CS65 to supply power only to the optocoupler U42, and does not flow to the driving module. After the short-circuit action driver is powered off, the short-circuit protection function can be maintained all the time, and when a next short-circuit signal is obtained, the short-circuit protection action can be still carried out, so that the safety of the circuit is improved.

The protection module 7 does not work after the VCC of the driving chip 41 is pulled to an undervoltage state. If the short-circuit protection of the detection module 6 does not disappear and the VCC of the driving chip 41 is powered off, the short-circuit protection signal at this time cannot work normally, and the chip power supply circuit 42 works at the interval time period of the VCC power supply of the driving chip 41 to output a larger current. After the power supply of the optocoupler U42 is independently increased, the short circuit information of the detection module 6 continuously switches on the triode QS62 through the optocoupler U42, and the voltage of the chip power supply loop 42 is lowered to an undervoltage state which enables the chip to be incapable of being started, so that the working time of the time interval is effectively delayed, and the effective value of the output current is reduced.

The driver adopts IW3627, when the AC power voltage is switched on, a resistor RS61 is quickly started by the chip to charge VIN, and MOS tube QS61 is controlled to charge C61 VCC through a resistor RS 62. When the voltage of the starting 14V is reached, the chip starts to work, the MOS tube Q41 is driven to be switched on, energy is stored through the flyback transformer L41, when the MOS tube Q41 is switched off, the first secondary side L41C of the transformer L41 is converted into an output end in a discharge mode, and the constant 24V voltage is output after the constant voltage is rectified through the diode D41 and subjected to electrolytic filtering through the electrolytic capacitor C42A.

When a short circuit occurs between the power output LED + and the LED-, the voltage of the current detection resistor R51 is raised, the voltage is input from the positive output end of the comparator US51 and compared with the reference voltage of the negative input end of the comparator US51, when the voltage of the positive input end exceeds 0.125V, the operational amplifier outputs high level, and the sinking current is limited to the optical coupler US42 signal through the diode DS51A and the resistor RS 58.

After the output short circuit, the output voltage is reduced to about 0V from 24V, and the highest voltage can reach a peak value of 5V when the internal resistances of the short circuit lines are different, so that the comparator US51 cannot work normally. A second secondary L41D2 turns of a forward winding transformer L41 is added. When the voltage is low after flyback forward short circuit, the reverse peak voltage is also very high, the electrolytic capacitor C56 is charged through the second secondary side L41D of the forward winding transformer L41 through rectification of the rectifier diode DS53, the voltage of more than 10V can be kept at two ends of the electrolytic capacitor C56 in a short circuit state, and the operational amplifier positive work and the optical coupling signal current of the optical coupler U42 are completely met. In the absence of a short circuit, the operational amplifier is powered directly from the output 24V via diode DS 54.

When the voltage VCC is switched on by the optocoupler US42, the voltage VCC is divided by the resistor RS59A and the resistor RS59B to charge the electrolytic capacitor C63, when the base of the triode QS62 reaches the switching-on voltage and the triode QS62 is switched on, the diode DS63 electrolyzes and discharges the electrolytic capacitor C61, and simultaneously the emitter follower chip power supply loop 42 formed by the winding of the third secondary side L41B of the transformer L41 through the diode DS61, the current limiting resistor RS63, the filter capacitor CS64, the resistor RS64 and the triode QS63 is cut off.

And the chip stops working after the VCC is powered off. The voltage on the capacitor CS65 is reversed by the diode DS62, the voltage on VCC is kept, when a short-circuit signal is found again in the later stage, the voltage of the optocoupler US42 is provided by the capacitor CS65, enough voltage is provided to enable the transistor QS62 to be switched on, and the charging voltage of VCC from the quick-charging circuit is continuously released. Because the capacity and voltage of the capacitor CS65 are high, the protective discharge operation can be maintained for a long time until the voltage cannot maintain the on state of the transistor QS 62. The chip will work again after the VCC is charged to 14.6V by the fast charging line. The effective protection time of the whole protection circuit is fast, and the pulse width of the output current is limited after the driving chip is restarted. And a low-power protection state after short circuit is achieved.

The utility model discloses a mode of opto-coupler power supply among the protection module relies on the electric capacity power supply after carrying out short-circuit protection action and loses the electricity, maintains the protection module and can last short-circuit protection. After short circuit loses the electricity, increase forward power supply circuit in the output module, ensure that comparator US51 can work always, can maintain short circuit detection state always after the short circuit loses the electricity, improved the security of circuit.

Claims

1. A driver short-circuit protection circuit comprises a voltage transformation module (1), a rectification module (2), a filtering module (3), a driving module (4) and an output module (5) which are sequentially connected, and is characterized by further comprising a detection module (6) and a protection module (7), wherein the detection end of the detection module (6) is connected with the output module (5), the output end of the detection module (6) is connected with the input end of the protection module (7), and the output end of the protection module (7) is connected with the driving module (4); the protection module (7) comprises an element which is used for continuously supplying power to the protection module (7) during short-circuit protection.

2. The driver short-circuit protection circuit as claimed in claim 1, wherein the protection module (7) comprises an optocoupler U42, a diode DS61, a diode DS6, a resistor RS63, a resistor RS64, a resistor RS59A, a resistor RS59B, a transistor QS62, a transistor QS63, a capacitor CS64 and an electrolytic capacitor C63; two ends of a diode of the optical coupler U42 are connected with the detection module (6), a collector of the optical coupler U42 is connected with a power supply end of the driving module (4), an emitter of the optical coupler U42 is connected with a first end of a resistor RS59A, a second end of the resistor RS59A is connected with a first end of a resistor RS59B, and a second end of the resistor RS59 is grounded; the positive terminal of the electrolytic capacitor C63 is connected with the first terminal of the resistor RS59B, and the negative terminal of the electrolytic capacitor C63 is grounded; the base electrode of the triode QS62 is connected with the positive electrode end of the electrolytic capacitor C63, the emitter electrode of the triode QS62 is grounded, the collector electrode of the triode QS62 is connected with the base electrode of the triode QS63, the emitter electrode of the triode QS63 is connected with the power supply end of the driving module (4), the collector electrode of the triode QS is connected with the first end of the resistor RS64, and the second end of the resistor RS64 is connected with the base electrode of the triode QS 63; the anode of the diode DS63 is connected with the emitter of the transistor QS63, and the cathode of the diode DS63 is connected with the base of the transistor QS 63; the first end of the capacitor CS64 is connected with the collector of the transistor QS63, the second end of the capacitor CS64 is grounded, the first end of the resistor RS63 is connected with the first end of the resistor RS64, the second end of the resistor RS63 is connected with the cathode of the diode DS61, and the anode of the diode DS61 is connected with the feedback end of the driving module (4).

3. A driver short-circuit protection circuit as claimed in claim 2, characterized in that said elements for continuously powering the protection module (7) are a diode DS62 and a capacitor CS 65; a first end of the capacitor CS65 is connected with a collector of the optocoupler U42, and a second end of the capacitor CS65 is grounded; the cathode of the diode DS62 is connected to the first end of the capacitor CS65, and the anode of the diode DS62 is connected to the power supply end of the driving module (4).

4. A driver short-circuit protection circuit according to claim 1, 2 or 3, characterized in that said detection module (6) comprises a resistor R51, a resistor RS52A, a resistor RS53A, a resistor RS53B, a resistor RS53D, a resistor RS58, a capacitor CS55, a capacitor CS51, a capacitor CS53, a diode DS51A, a voltage regulator ZS51 and a comparator US 51; the two ends of the resistor R51 are connected with the output module (5), the first end of the capacitor CS55 is connected with the first end of the resistor R51, the second end of the capacitor CS55 is connected with the second end of the resistor R51, the second end of the resistor R51 is connected with the first end of the resistor RS52A, the second end of the resistor RS52A is connected with the first end of the capacitor CS51, and the second end of the capacitor CS51 is grounded; the positive input end of the comparator US51 is connected with the second end of the resistor RS52A, the output end of the comparator US51 is connected with the anode of the diode DS51A, the cathode of the diode DS51A is connected with the first end of the resistor RS58, and the second end of the resistor RS58 is connected with the protection module (7); a first end of the capacitor CS52 is connected with the output end of the comparator US51, and a second end of the capacitor CS52 is connected with the negative input end of the comparator US 51; the negative input end of the comparator US51 is connected with the first end of the resistor RS53B, the first end of the resistor RS53D is connected with the negative input end of the comparator US51, and the second end of the resistor RS53D is grounded; the second end of the resistor RS53B is connected with the cathode of the voltage regulator ZS51, the anode of the voltage regulator ZS51 is grounded, the cathode of the voltage regulator ZS51 is connected with the first end of the capacitor CS53, and the second end of the capacitor CS53 is grounded; the first end of the resistor RS53A is connected with the output end of the output module (5), and the second end of the resistor RS53A is connected with the first end of the capacitor CS 53.

5. A driver short-circuit protection circuit according to claim 4, characterized in that the output module (5) comprises a forward power supply loop for supplying power to the comparator US 51; the forward power supply loop comprises a transformer L41, a diode DS53 and an electrolytic capacitor C56; a primary side L41A of the transformer L41 is an output end of the driving module (4), a first secondary side L41C of the transformer L41 is an input end of the output module (5), a first end of a second secondary side L41D of the transformer L41 is connected with a first secondary side L41C of the transformer L41, a second end of a second secondary side L41D of the transformer L41 is connected with an anode of a diode DS53, a cathode of the diode DS53 is connected with a positive end of an electrolytic capacitor C56, and a negative end of the electrolytic capacitor C56 is grounded; the positive terminal of the electrolytic capacitor C56 is connected with the power supply terminal of the comparator US 51.

6. A driver short-circuit protection circuit according to claim 1, wherein the driving module (4) comprises a driving chip (41) and a peripheral loop connected to the driving chip (41), the peripheral loop comprising a chip power supply loop (42), a voltage feedback loop (44), a chip output loop (43) and a current feedback loop (45); the input end of the chip power supply loop (42) is connected with the output end of the filtering module (3), and the output end of the chip power supply loop (42) is connected with the protection module (7); the input end of the chip output loop (43) is connected with the output end of the filtering module (3), and the output end of the chip output loop (43) is connected with the output module (5).

7. The driver short-circuit protection circuit of claim 6, wherein the chip power supply circuit (42) comprises a resistor RS61, a resistor RS62, a capacitor CS62, an electrolytic capacitor C61 and a MOS transistor QS 61; the first end of the resistor RS61 is connected with the output end of the filter module (3), the second end of the resistor RS61 is connected with the gate of the MOS transistor QS61, the first end of the resistor RS62 is connected with the first end of the resistor RS61, and the second end of the resistor RS62 is connected with the drain of the MOS transistor QS 61; the source of the MOS transistor QS61 is connected with the first end of the capacitor CS62, the second end of the capacitor CS62 is grounded, the first end of the capacitor CS62 is connected with the positive electrode end of the electrolytic capacitor C61, and the second end of the electrolytic capacitor C61 is grounded; the source of the MOS tube QS61 is connected with the power supply end of the driving chip (41), the source of the MOS tube is connected with the protection circuit, and the second end of the resistor RS61 is connected with the high-voltage starting end of the driving chip (41).