Multi-output dimming power supply

Abstract

The application relates to the technical field of dimming power supply, and discloses a multi-channel output dimming power supply which comprises a power supply main circuit, a plurality of power control tubes, a control circuit, a primary protection circuit and a secondary protection circuit. The input end of the power supply main circuit is connected with external power supply, the positive pole of the output end is connected with the positive poles of a plurality of lamp loads, and the negative pole of the output end is connected with the common ground of the dimming power supply. The source poles of the plurality of power control tubes are all connected with the common ground, the drain poles are connected with the negative poles of the corresponding lamp loads, and the plurality of output ends of the control circuit are connected with the gate poles of the plurality of power control tubes. The primary protection circuit is used for sending a short-circuit detection signal to the feedback end of the control circuit when the positive pole of any lamp load is at the same potential as the common ground, so that the control circuit closes the output of the output end. The secondary protection circuit is used for lowering the gate voltage of the power control tube when the positive pole and the negative pole of any lamp load are at the same potential. The dimming power supply can realize reliable short-circuit protection at a lower cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dimming power supply, in particular to a multi-output dimming power supply. BACKGROUND

[0002] With the advent of dimming power supply, various dimming power supplies appear. The constant voltage dimming power supply generally controls the dimming through the power MOS tube at the output end. When the output occurs short circuit, the power MOS tube may be damaged due to the too large power output at the moment or continuously during the short circuit. Therefore, in order to avoid the occurrence of the above phenomenon, the dimming power supply on the market will set a short circuit protection circuit to protect the power device from being damaged when short circuit occurs. At present, the short circuit protection scheme on the market is to connect a sampling resistor in series at the output end, and to trigger the short circuit protection by collecting the output current. This short circuit protection scheme is relatively simple and effective for single output, but for the dimming power supply with multiple outputs, it is necessary to set a sampling resistor for each output, so that the short circuit protection process becomes cumbersome, and the cost increases with the increase of the number of outputs, greatly increasing the cost of short circuit protection. Therefore, it is necessary to design a new short circuit protection scheme suitable for the multi-output dimming power supply. SUMMARY

[0003] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a multi-output dimming power supply which can reduce the cost of short circuit protection.

[0004] To solve the above problems, the technical scheme adopted by the present application is as follows: a multi-output dimming power supply, comprising: a power supply main circuit, an input end connected with external power supply, a positive electrode of an output end connected with positive electrodes of a plurality of lamp loads, and a negative electrode of the output end connected with a common ground of the dimming power supply, for converting the external power supply into direct current required by the lamp load; a plurality of power control tubes, respectively arranged between the negative electrode of the output end of the power supply main circuit and the negative electrode of the corresponding lamp load, the source electrodes of the plurality of power control tubes are all connected with the common ground, and the drain electrodes of the power control tubes are connected with the negative electrodes of the corresponding lamp load; a control circuit, a plurality of output ends are connected with gate electrodes of the plurality of power control tubes respectively, for controlling switching frequencies of the plurality of power control tubes; a primary protection circuit, an input end connected with the positive electrodes of the plurality of lamp loads, and an output end connected with a feedback end of the control circuit, for sending a short circuit detection signal to the feedback end of the control circuit when the positive electrode of any lamp load is at the same potential as the common ground, so as to close the output of the control circuit; a secondary protection circuit, a plurality of first input ends connected with the negative electrodes of the plurality of lamp loads respectively, a second input end connected with the positive electrodes of the plurality of lamp loads, and a plurality of output ends connected with the gate electrodes of the plurality of power control tubes respectively, for pulling down the gate voltage of the plurality of power control tubes when any first input end is at the same potential as the second input end.

[0005] Compared with the prior art, the application has the beneficial effects that: by connecting multiple lamp loads in common anode connection, and by detecting whether the potential of the positive pole of the multiple lamp loads connected in parallel is equal to the potential of the common ground of the power supply through a primary protection circuit, short circuit detection of the lamp load is realized, thereby avoiding setting a sampling resistor on each output, and reducing the short circuit protection cost of the multi-output dimming power supply. The secondary protection circuit detects whether the positive pole and the negative pole of the lamp load are equal in potential to determine whether the short circuit protection is triggered, and when the short circuit protection is triggered, the gate voltage of the power control tube is pulled down to make the power control tube off, preventing the power control tube from being mis-triggered and burned when the short circuit protection is triggered, and further enhancing the reliability of the short circuit protection of the power control tube.

[0006] The multi-output dimming power supply has a primary protection circuit including a detection voltage dividing circuit and a control voltage dividing circuit, a first end of the detection voltage dividing circuit is connected to the positive poles of the multiple lamp loads, a second end of the detection voltage dividing circuit is connected to the common ground, a first end of the control voltage dividing circuit is connected to the first voltage, a second end of the control voltage dividing circuit is connected to the common ground, a protection control tube is connected in series in the control voltage dividing circuit, a gate of the protection control tube is connected to a voltage dividing end of the detection voltage dividing circuit, and the voltage dividing end of the control voltage dividing circuit is connected to a feedback end of the control circuit.

[0007] The multi-output dimming power supply has a detection voltage dividing circuit including resistors R7 and R8, one end of the resistor R7 is connected to the positive poles of the multiple lamp loads, the other end of the resistor R7 is grounded, and a connection node between the resistors R7 and R8 is connected to a gate of the protection control tube as a voltage dividing end of the detection voltage dividing circuit.

[0008] The multi-output dimming power supply has a control voltage dividing circuit further including resistors R5 and R6, a source of the protection control tube is connected to the first voltage through the resistor R5, a drain of the protection control tube is connected to the common ground through the resistor R6, and the drain of the protection control tube is connected to a feedback end of the control circuit as a voltage dividing end of the control voltage dividing circuit.

[0009] The multi-output dimming power supply, the secondary protection circuit comprises a detection circuit and a control circuit, the control circuit comprises a plurality of controllable switching devices, first ends of the plurality of controllable switching devices are connected with gates of the plurality of power control tubes respectively, second ends of the plurality of controllable switching devices are connected with the common ground, control ends of the plurality of controllable switching devices are connected with an output end of the detection circuit and controlled by the detection circuit, a plurality of first input ends of the detection circuit are connected with negative poles of the plurality of lamp loads respectively, a second input end of the detection circuit is connected with positive poles of the plurality of lamp loads, and the detection circuit controls the plurality of controllable switching devices to be turned on when any first input end and the second input end of the detection circuit are at the same potential, so that the gates of the plurality of power control tubes are grounded.

[0010] The multi-output dimming power supply, the controllable switching device is an NMOS tube, a gate of the controllable switching device is connected with the output end of the detection circuit, a drain of the controllable switching device is connected with the gate of the corresponding power control tube, and a source of the controllable switching device is connected with the common ground.

[0011] The multi-output dimming power supply, the detection circuit comprises a detection triode which is a P-type triode, an emitter of the detection triode is connected with negative poles of the plurality of lamp loads through a plurality of first diodes respectively, positive poles of the first diodes are connected with negative poles of the corresponding lamp loads, negative poles of the first diodes are connected with the emitter of the detection triode, a base of the detection triode is connected with positive poles of the plurality of lamp loads through a plurality of second diodes connected in series, a positive pole of the outermost second diode is connected with the positive pole of the lamp load, a negative pole of the innermost second diode is connected with the base of the detection triode, and the emitter of the detection triode is connected with the control end of the plurality of controllable switching devices.

[0012] The multi-output dimming power supply, the detection circuit further comprises resistors R3 and R4, a collector of the detection triode is connected with the common ground through the resistors R3 and R4 in sequence, and a connection node between the resistors R3 and R4 is connected with the base of the plurality of controllable switching devices.

[0013] The multi-output dimming power supply, the detection circuit further comprises a capacitor C1, and the capacitor C1 is connected across the resistor R4 in parallel.

[0014] The multi-output dimming power supply, the detection circuit further comprises resistors R1 and R2, the base of the detection triode is connected with the common ground through the resistors R1 and R2 in sequence, and a connection node between the resistors R1 and R2 is connected with the negative pole of the innermost second diode.

[0015] The application will be further described in detail below in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The principle block diagram of the multi-output dimming power supply of the embodiment of the present application.

[0017] Figure 2 The circuit principle diagram of the multi-output dimming power supply of the embodiment of the present application.

[0018] BRIEF DESCRIPTION OF DRAWINGS

[0019] 100, power supply main circuit, 200, control circuit, 300, primary protection circuit, 400, secondary protection circuit. DETAILED DESCRIPTION

[0020] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. Figure 1 The embodiments of the present application provide a multi-output dimming power supply, which comprises a power supply main circuit 100, a plurality of power control tubes QL1, QL2 to QLn, a control circuit 200, a primary protection circuit 300 and a secondary protection circuit 400. The input end of the power supply main circuit 100 is connected with external power supply of alternating current or direct current, the positive pole of the output end is connected with the positive poles of a plurality of lamp loads, the negative pole of the output end is connected with the common ground GSN of the dimming power supply, and is connected with the negative poles of the lamp loads through the plurality of power control tubes respectively. The power supply main circuit 100 is used for converting the external power supply into direct current required by the lamp loads. The number of the power control tubes is consistent with the number of the output channels of the dimming power supply required. The source poles of the power control tubes are all connected with the common ground GSN of the power supply, the gate poles are connected with the corresponding output ends of the control circuit 200, and the drain poles are connected with the negative poles of the corresponding lamp loads. The control circuit 200 is used for controlling the switching frequency of the power control tubes, so as to adjust the power output to the lamp loads, and to realize the adjustment of the brightness or color temperature of the lamp loads. The input end of the primary protection circuit 300 is connected with the positive poles of the lamp loads, and the output end is connected with the feedback end of the control circuit 200. When the primary protection circuit 300 detects that the input end is at the same potential as the common ground GSN, it is judged that a short circuit of the lamp load occurs, a short circuit detection signal is fed back to the control circuit 200, the output of the output end of the control circuit 200 is turned off, and the short circuit protection of the power control tube is realized. The plurality of first output ends of the secondary protection circuit 400 are connected with the negative poles of the lamp loads respectively, the second input end is connected with the positive poles of the lamp loads, and the plurality of output ends are connected with the gate poles of the power control tubes respectively. When the secondary protection circuit 400 detects that the first output end and the second input end are at the same potential, it is judged that the short circuit protection is triggered, the gate poles of the power control tubes are all pulled down, the power control tubes are prevented from being mis-triggered, and the power control tubes are further prevented from being burned out by the short circuit current when the short circuit occurs.

[0021] The multi-output dimming power supply can detect whether the potential of the positive pole of the lamp is equal to the potential of the common ground GSN through the one-stage protection circuit 300, so as to realize short circuit detection of any lamp load, avoid setting a sampling resistor, avoid increasing the number of sampling resistors when the number of output paths is increased, and thus reduce the cost of short circuit protection of the multi-output dimming power supply. In addition, it is not necessary to set a detection circuit for each output path, so that the area of the circuit is reduced, the miniaturization of the dimming power supply is facilitated, and the cost of short circuit protection of the power supply will not be significantly increased with the increase of the number of output paths. Meanwhile, when the short circuit protection is triggered, the dimming power supply further pulls the gate of the power control tube low through the two-stage protection circuit 400, so as to further avoid the conduction of the power control tube when the lamp load is short-circuited, and improve the reliability of the short circuit protection.

[0022] With reference to Figure 2 In some embodiments, the one-stage protection circuit 300 includes a detection voltage dividing circuit and a control voltage dividing circuit, one end of the one-stage protection circuit 300 is connected with the positive poles of a plurality of lamp loads, and the other end is connected with the common ground GSN. One end of the two-stage protection circuit 400 is connected with the first voltage VCC, and the other end is connected with the common ground GSN. The control voltage dividing circuit has the protection control tube Q2 connected in series. The gate of the protection control tube Q2 is connected with the voltage dividing end of the detection voltage dividing circuit, and the voltage dividing end of the control voltage dividing circuit is connected with the feedback end of the control circuit 200. In this embodiment, the protection control tube Q2 is a PMOS tube. In normal operation, the detection voltage dividing circuit divides the voltage of the positive pole of the lamp load, i.e. the voltage of the positive pole of the main circuit 100 of the power supply, and then transmits the voltage to the gate of the protection control tube Q2, so as to avoid breakdown and burnout of the protection control tube Q2. At this time, the gate voltage of the protection control tube Q2 is higher than the source voltage of the protection control tube Q2, and the protection control tube Q2 is turned off. When any lamp load is short-circuited, the positive pole of the short-circuited lamp load is equal to the common ground GSN, the gate voltage of the protection control tube Q2 is lower than the source voltage of the protection control tube Q2, and the protection control tube Q2 is turned on. Thus, the voltage output by the voltage dividing end of the control voltage dividing circuit changes, a short circuit detection signal is generated, the control circuit 200 is informed that the lamp load is short-circuited, the PWM signal output by the output end of the control circuit 200 is stopped, and the short circuit protection of the power control tube is realized.

[0023] With reference to Figure 2In the embodiment, the detection voltage dividing circuit comprises resistors R7 and R8 connected in series, and a connection node between the resistors R7 and R8 is connected with the gate of the protection control tube Q2. The control voltage dividing circuit further comprises resistors R5 and R6, the source of the protection control tube Q2 is connected with the first voltage VCC through the resistor R5, the drain is grounded through the resistor R6, and is connected with the feedback end of the control circuit 200. In normal operation, the feedback end of the control circuit 200 is connected with the common ground GSN, and is a low level. When the lamp load short circuit occurs, the voltage inputted by the feedback end of the control circuit 200 is a high level which is consistent with the input range requirement of the feedback end of the control circuit 200, and is obtained by dividing the first voltage VCC through the resistors R5 and R6, so as to feedback to the control circuit 200 that the lamp load short circuit occurs.

[0024] With reference to Figure 2 The secondary protection circuit 400 comprises a detection circuit and the control circuit 200. The control circuit 200 comprises a plurality of controllable switching devices, the first ends of the controllable switching devices are respectively connected with the gates of the plurality of power control tubes, the second ends of the controllable switching devices are all connected with the common ground GSN, the control ends of the controllable switching devices are connected with the output end of the detection circuit and are controlled by the detection circuit. The plurality of first input ends of the detection circuit are respectively connected with the negative poles of the plurality of lamp loads, and the second input end is connected with the positive poles of the plurality of lamp loads. When the detection circuit detects that any first input end is at the same potential as the second input end, the control circuit 200 controls all the controllable switching devices to be turned on, so as to pull down the gate voltage of the power control tube to the common ground GSN, thereby avoiding the power control tube from being mis-triggered to be turned on, and improving the reliability of the short circuit protection. It can be understood that the controllable switching device can be a MOS tube, a triode or a relay, etc.

[0025] With reference to Figure 2In the embodiment, the controllable switching devices are NMOS tubes QG1, QG2 to QGn, the drain of the controllable switching device is connected with the gate of the corresponding power control tube, the source is connected with the common ground GSN, and the gate is connected with the output of the detection circuit. The detection circuit comprises a detection triode Q1 which is a P-type triode. The emitter of the detection triode Q1 is connected with the negative pole of the plurality of lamp loads through a plurality of reverse-connected first diodes DL1, DL2 to DLn respectively. The base of the detection triode Q1 is connected with the common ground GSN through resistors R1 and R2 in sequence. The connection node between the resistors R1 and R2 is connected with the positive pole of the plurality of lamp loads through three reverse-connected second diodes D1 to D3 in series. The collector of the detection triode Q1 is connected with the common ground GSN through resistors R3 and R4 in sequence. The connection node between the resistors R3 and R4 is connected with the gate of each controllable switching device as the output of the detection circuit and is fed back to the control circuit 200. The two ends of the resistor R4 are connected with the capacitor C1 in parallel to filter the output of the detection circuit and prevent the output of the detection circuit from jumping. When the short-circuit protection is triggered, all the power control tubes are turned off, the lamp load is in a short-circuit state, the positive pole and the negative pole of the lamp load are at the same potential, the detection triode Q1 is turned on from off, the negative pole voltage of the lamp load is transmitted to the control circuit 200 and the gate of the controllable switching device after being divided by the resistors R3 and R4, and the NMOS tubes QG1, QG2 to QGn are turned on, so that the gate of the power control tube is pulled down to the common ground GSN, and the short-circuit protection of the power control tube is strengthened.

[0026] It can be understood that the power main circuit 100 can be a switching power supply circuit composed of a rectifier filter circuit, a power conversion circuit and the like, the control circuit 200 can be composed of a MOS tube driving IC and its peripheral circuit or a MOS tube driving circuit, and the specific structure of the power main circuit 100 and the control circuit 200 is well known in the art, which will not be described here.

[0027] It should be noted that in the description of the present application, if there is a description of the orientation, such as the orientation or position relationship indicated by the upper, lower, front, rear, left, right and the like, it is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and cannot be understood as indicating or implying that the indicated device or element must have a specific orientation, be constructed or operated in a specific orientation, and cannot be understood as a limitation on the present application.

[0028] In the description of the present application, several meanings are one or more, and multiple meanings are two or more. Greater than, less than, more than and the like are not included in the number. Above, below, within and the like are understood to include the number. If there is a description of the first or second, it is only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0029] In the description of the application, unless otherwise explicitly defined, the words setting, installing, connecting and the like should be understood broadly, and the person skilled in the art can reasonably determine the specific meaning of the above words in the application in combination with the specific content of the technical solution.

[0030] The above embodiments are only preferred embodiments of the application, and cannot be used to limit the protection scope of the application. Any non-essential changes and substitutions made by the person skilled in the art on the basis of the application shall fall within the protection scope of the application.

Claims

1. A multi-output dimming power supply, characterized in that, include: The main power supply circuit (100) has an input terminal connected to an external power supply, an output terminal with a positive terminal connected to the positive terminal of multiple lamp loads, and an output terminal with a negative terminal connected to the common ground of the dimming power supply. It is used to convert the external power supply to the DC power required by the lamp loads. Multiple power control transistors are respectively disposed between the negative terminal of the output terminal of the main power circuit (100) and the negative terminal of the corresponding lamp load. The sources of the multiple power control transistors are all connected to the common ground, and the drains of the power control transistors are connected to the negative terminal of the corresponding lamp load. The control circuit (200) has multiple output terminals connected to the gates of multiple power control transistors respectively, and is used to control the switching frequency of the multiple power control transistors; The first-level protection circuit (300) has its input terminal connected to the positive terminal of multiple lamp loads and its output terminal connected to the feedback terminal of the control circuit (200). It is used to send a short-circuit detection signal to the feedback terminal of the control circuit (200) when the positive terminal of any lamp load is at the same potential as the common ground, so that the control circuit (200) shuts off the output of its output terminal. The secondary protection circuit (400) has multiple first input terminals connected to the negative terminals of multiple lamp loads, a second input terminal connected to the positive terminals of multiple lamp loads, and multiple output terminals connected to the gates of multiple power control transistors, for pulling down the gate voltage of multiple power control transistors when any of the first input terminals and the second input terminals are at the same potential.

2. The multi-output dimming power supply according to claim 1, characterized in that, The primary protection circuit (300) includes a detection voltage divider circuit and a control voltage divider circuit. The first terminal of the detection voltage divider circuit is connected to the positive terminal of multiple lamp loads, and the second terminal of the detection voltage divider circuit is connected to the common ground. The first terminal of the control voltage divider circuit is connected to a first voltage, and the second terminal of the control voltage divider circuit is connected to the common ground. A protection control transistor is connected in series in the control voltage divider circuit. The gate of the protection control transistor is connected to the voltage divider terminal of the detection voltage divider circuit, and the voltage divider terminal of the control voltage divider circuit is connected to the feedback terminal of the control circuit (200).

3. The multi-output dimming power supply according to claim 2, characterized in that, The detection voltage divider circuit includes resistors R7 and R8. One end of resistor R7 is connected to the positive terminal of multiple lamp loads, and the other end of resistor R7 is grounded. The connection node between resistors R7 and R8 serves as the voltage divider terminal of the detection voltage divider circuit and is connected to the gate of the protection control tube.

4. The multi-output dimming power supply according to claim 2, characterized in that, The control voltage divider circuit also includes resistors R5 and R6. The source of the protection control transistor is connected to the first voltage through resistor R5, and the drain of the protection control transistor is connected to the common ground through resistor R6. The drain of the protection control transistor is connected to the feedback terminal of the control circuit (200) as the voltage divider terminal of the control voltage divider circuit.

5. The multi-output dimming power supply according to claim 1, characterized in that, The secondary protection circuit (400) includes a detection circuit and a control circuit (200). The control circuit (200) includes multiple controllable switching devices. The first terminals of the multiple controllable switching devices are respectively connected to the gates of the multiple power control transistors. The second terminals of the multiple controllable switching devices are all connected to the common ground. The control terminals of the multiple controllable switching devices are connected to the output terminals of the detection circuit and are controlled by the detection circuit. The multiple first input terminals of the detection circuit are respectively connected to the negative terminals of the multiple lamp loads. The second input terminal of the detection circuit is connected to the positive terminals of the multiple lamp loads. When any of its first input terminals and second input terminals are at the same potential, the detection circuit controls the multiple controllable switching devices to conduct, so that the gates of the multiple power control transistors are grounded.

6. The multi-output dimming power supply according to claim 5, characterized in that, The controllable switching device is an NMOS transistor. The gate of the controllable switching device is connected to the output terminal of the detection circuit, the drain of the controllable switching device is connected to the gate of the corresponding power control transistor, and the source of the controllable switching device is connected to the common ground.

7. The multi-output dimming power supply according to claim 5, characterized in that, The detection circuit includes a detection transistor, which is a P-type transistor. The emitter of the detection transistor is connected to the negative terminal of multiple lamp loads through multiple first diodes. The anode of the first diode is connected to the negative terminal of the corresponding lamp load. The cathode of the first diode is connected to the emitter of the detection transistor. The base of the detection transistor is connected to the positive terminal of multiple lamp loads through multiple second diodes connected in series. The anode of the outermost second diode is connected to the positive terminal of the lamp load, and the cathode of the innermost second diode is connected to the base of the detection transistor. The emitter of the detection transistor is connected to the control terminal of multiple controllable switching devices.

8. The multi-output dimming power supply according to claim 7, characterized in that, The detection circuit also includes resistors R3 and R4. The collector of the detection transistor is connected to the common ground in sequence through resistors R3 and R4. The connection node between resistors R3 and R4 is connected to the base of the multiple controllable switching devices.

9. The multi-output dimming power supply according to claim 8, characterized in that, The detection circuit also includes a capacitor C1, which is connected in parallel across the resistor R4.

10. The multi-output dimming power supply according to claim 7, characterized in that, The detection circuit also includes resistors R1 and R2. The base of the detection transistor is connected to the common ground in sequence through resistors R1 and R2. The connection node between resistors R1 and R2 is connected to the negative terminal of the innermost second diode.

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