CN111954342A - Dimming control circuit, dimming control method and LED drive circuit - Google Patents
Dimming control circuit, dimming control method and LED drive circuit Download PDFInfo
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Abstract
The invention provides a dimming control circuit, a dimming control method and an LED drive circuit, wherein the dimming control circuit comprises a logic level conversion circuit and a drive control circuit. The current sampling terminal of the dimming control circuit is coupled to an inductor in the LED driving circuit to sample the current flowing through the inductor. The logic level conversion circuit is used for receiving the first dimming signal and outputting a second dimming signal through a level conversion process, and the reference ground of the logic level conversion circuit is an input ground. The input end of the drive control circuit is coupled with the logic level conversion circuit, the drive control circuit is used for controlling the on-off state of a first switch tube in the LED drive circuit according to a second dimming signal so as to realize dimming control, and the reference ground of the drive control circuit is a floating ground. The dimming control circuit, the dimming control method and the LED drive circuit can effectively improve the dimming precision of the LED drive circuit and solve the problem of control signal transmission of a non-common-ground circuit in the LED drive circuit.
Description
Technical Field
The invention belongs to the field of electronics, relates to an LED driving technology, and particularly relates to a dimming control circuit, a dimming control method and an LED driving circuit.
Background
The LED lamp is widely applied to the field of illumination due to the characteristics of high brightness, low power consumption, long service life and the like. With the continuous innovation of LED driving technology, user requirements are changing continuously, and the requirements of high brightness and low efficiency, which are originally required, gradually change to the requirements of dimming characteristics and light quality. The intelligent lighting is used as a part of an intelligent home, and a user can carry out dimming and color mixing control according to the current use requirement to obtain the required lighting condition.
Fig. 1 shows a Buck type LED driving circuit. The LED driving circuit comprises a wireless module and a driving control circuit, and the LED constant current driving control is realized by collecting the current flowing through a transistor Q. The output end of the wireless module is coupled with the input end of the drive control circuit, the wireless module is used for receiving the control signal of the user end and sending a dimming signal to the drive control circuit to realize dimming of the LED drive circuit, and the wireless module can be a WIFI module or a Bluetooth module and the like. However, the scheme has accuracy errors, and the scheme estimates the magnitude of the output current by sampling the peak current flowing through the transistor Q and sampling and holding the peak current, namely the control process cannot accurately reflect the magnitude of the output current. In addition, in the sampling and holding process, errors also exist due to inaccurate sampling time, and the current flowing through the LED lamp cannot be accurately represented, so that the control precision of the output current is not high. With the increasing dimming requirement, the dimming depth needs to meet the requirement of adjusting from 100% to 1% ± 20%, for example, 100% of the maximum brightness of the LED, and the corresponding current flowing through the LED lamp is 100 mA. When the LED lamp is dimmed to 1% of the maximum brightness of the LED, the current correspondingly flowing through the LED lamp is 1mA, the dimming error is +/-20% and is correspondingly 0.2mA, the dimming error of 0.2mA is very low, and the dimming control with the precision is difficult to realize by the prior art scheme. When the requirement of dimming depth becomes 1 ‰ ± 20%, the above-mentioned existing scheme is more difficult to realize precise control.
In view of the above, it is desirable to provide a new structure or control method for solving the above problem of dimming accuracy of the LED driving circuit.
Disclosure of Invention
In order to solve at least part of the problems, the invention provides a dimming control circuit, a dimming control method and an LED drive circuit, which can effectively improve the dimming precision of the LED drive circuit and solve the problem of control signal transmission of a non-common-ground circuit in the LED drive circuit.
The invention discloses a dimming control circuit for an LED drive circuit, wherein a current sampling end of the dimming control circuit is coupled with an inductor in the LED drive circuit, the dimming control circuit controls the on-off state of a first switching tube in the LED drive circuit according to a sampling current so as to realize the constant current output of the LED drive circuit, and the sampling current represents the current flowing through the inductor. The dimming control circuit includes:
the input end of the logic level conversion circuit receives a first dimming signal from the signal sending module, the reference ground of the logic level conversion circuit is input ground, and the logic level conversion circuit is used for receiving the first dimming signal and outputting a second dimming signal through a level conversion process; the first dimming signal is a signal based on a reference ground as an input ground; and
the input end of the driving control circuit is coupled with the logic level conversion circuit, the reference ground of the driving control circuit is a floating ground, and the driving control circuit is used for controlling the switching state of the first switching tube according to the second dimming signal so as to realize dimming control; the level conversion process is to convert the first dimming signal with reference to the input ground into the second dimming signal with reference to the floating ground.
In an embodiment of the invention, a ground terminal of the driving control circuit is coupled to a floating terminal, the floating terminal is coupled to a first terminal of the inductor, and a second terminal of the inductor is coupled to an output terminal of the LED driving circuit.
In an embodiment of the invention, a high voltage input terminal of the driving control circuit is coupled to a dc bus of the LED driving circuit.
In an embodiment of the invention, the power supply terminal of the driving control circuit is coupled to the floating terminal through a second capacitor.
In an embodiment of the present invention, the dimming control circuit further includes:
the input end of the signal sending module receives a control signal from the user terminal, and the output end of the signal sending module is coupled with the logic level conversion circuit and used for converting the control signal of the user terminal into a first dimming signal.
In one embodiment of the present invention, a logic level converting circuit includes:
a NOT gate, an input end of which receives a first dimming signal;
a control terminal of the second switch tube is coupled to the not gate, and a second terminal of the second switch tube is coupled to the input ground;
a first end of the second resistor is coupled with a first voltage;
a first end of the third resistor is coupled to the second end of the second resistor, and a second end of the third resistor is coupled to the first end of the second switch tube; and
the cathode of the second diode is coupled to the second end of the second resistor, the anode of the second diode is coupled to the floating ground, and the cathode of the second diode outputs a second dimming signal.
In one embodiment of the present invention, a logic level converting circuit includes:
the input end of the rising edge acquisition circuit receives a first dimming signal and is used for acquiring the rising edge of the first dimming signal;
the input end of the falling edge obtaining circuit receives a first dimming signal and is used for obtaining the falling edge of the first dimming signal; and
and the trigger circuit is coupled with the rising edge acquisition circuit at a set end, coupled with the falling edge acquisition circuit at a reset end, and coupled with the floating end at a ground end, and used for generating a second dimming signal according to signals sent by the rising edge acquisition circuit and the falling edge acquisition circuit.
In an embodiment of the invention, a current sampling terminal of the driving control circuit is coupled to a first terminal of a first resistor, and a second terminal of the first resistor is coupled to a floating terminal.
In an embodiment of the invention, a current sampling terminal of the logic level converting circuit is coupled to a first terminal of a first resistor, and a second terminal of the first resistor is coupled to an input ground terminal.
In an embodiment of the invention, the logic level converting circuit and the driving control circuit are packaged in the same package.
The invention discloses an LED driving circuit which comprises a rectifying circuit, a first switching tube, an inductor, a first diode, an output capacitor and a dimming control circuit.
In an embodiment of the present invention, the first switch tube, the inductor, the first diode, and the output capacitor form a Buck-type switch circuit, the first resistor is further coupled between the first switch tube and the inductor, the first end of the inductor is coupled to the floating end, and the second end of the inductor is coupled to the output end of the LED driving circuit.
In an embodiment of the invention, a current sampling terminal of the dimming control circuit is coupled to a first terminal of a first resistor, and a second terminal of the first resistor is coupled to a first terminal of an inductor.
The invention discloses a dimming control method for an LED drive circuit, wherein the LED drive circuit comprises a dimming control circuit, the dimming control circuit controls the on-off state of a first switching tube in the LED drive circuit according to sampling current so as to realize constant current output of the LED drive circuit, and the sampling current represents the current flowing through an inductor in the LED drive circuit; the dimming control method comprises the following steps:
receiving a first dimming signal from a signal sending module; the first dimming signal is a signal based on a reference ground as an input ground;
converting a first dimming signal with reference to the ground as an input ground into a second dimming signal with reference to the ground as a floating ground; and
and controlling the on-off state of a first switching tube in the LED driving circuit according to the second dimming signal to realize dimming control.
The invention provides a dimming control circuit, a dimming control method and an LED drive circuit, wherein the dimming control circuit comprises a logic level conversion circuit and a drive control circuit. The current sampling terminal of the dimming control circuit is coupled to an inductor in the LED driving circuit to sample the current flowing through the inductor. The dimming control circuit controls the on-off state of a first switching tube in the LED driving circuit according to the sampling current so as to realize constant current output of the LED driving circuit, and the sampling current represents the current flowing through an inductor in the LED driving circuit. According to the dimming control circuit, the dimming control method and the LED drive circuit, the current flowing through the inductor can be collected, and the current flowing through the inductor is consistent with the current flowing through the LED lamp, so that the sampling current can directly represent the output current of the LED drive circuit, no redundant error is introduced in the middle, and the LED constant current control precision is far higher than that of the prior art. In addition, the first dimming signal with reference ground as the input ground is converted into the second dimming signal with reference ground as the floating ground through the logic level conversion circuit, and the problem of control signal transmission of a non-common ground circuit in the LED driving circuit is effectively solved.
Drawings
Fig. 1 shows a circuit schematic of a prior art LED driver circuit.
Fig. 2 shows a circuit schematic of an LED driving circuit according to an embodiment of the present invention.
Fig. 3 shows a circuit schematic of an LED driver circuit according to another embodiment of the invention.
Fig. 4 shows a circuit schematic of a logic level shifting circuit according to an embodiment of the present invention.
Fig. 5 shows a circuit schematic of a logic level shifting circuit according to another embodiment of the present invention.
Fig. 6 shows a circuit schematic of an LED driving circuit according to another embodiment of the present invention.
Fig. 7 is a schematic diagram illustrating steps of a dimming control method for an LED driving circuit according to an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. It is within the scope of the present disclosure and protection that the same or similar prior art means and some features of the embodiments may be interchanged.
The term "coupled" or "connected" in this specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a connection made through an electrically conductive medium, which may have parasitic inductance or parasitic capacitance; indirect connections may also include connections through other active or passive devices, such as connections through switches, follower circuits, etc., that serve the same or similar functional purpose. In the claims and the description, the "end" is not limited to a physical port of a control circuit or a chip, but may be a circuit node or a circuit connection point in a circuit.
The embodiment of the invention discloses a dimming control circuit for an LED drive circuit, wherein a current sampling end of the dimming control circuit is coupled with an inductor in the LED drive circuit to sample current flowing through the inductor, the dimming control circuit controls the on-off state of a first switching tube in the LED drive circuit according to the sampling current to realize constant current output of the LED drive circuit, and the sampling current represents the current flowing through the inductor. The dimming control circuit comprises a logic level conversion circuit and a driving control circuit. The input end of the logic level conversion circuit receives a first dimming signal from the signal sending module, the reference ground of the logic level conversion circuit is an input ground, and the logic level conversion circuit is used for receiving the first dimming signal and outputting a second dimming signal through a level conversion process. The first dimming signal is a signal based on the reference ground being an input ground. The input end of the driving control circuit is coupled to the output end of the logic level conversion circuit, the reference ground of the driving control circuit is a floating ground, and the driving control circuit is used for controlling the on-off state of a first switch tube in the LED driving circuit according to a second dimming signal so as to realize dimming control. The level conversion process is to convert a first dimming signal with reference ground as an input ground into a second dimming signal with reference ground as a floating ground, so that the problem of control signal transmission of a non-common ground circuit in the LED driving circuit is solved.
As shown in fig. 2, an embodiment of the present invention discloses an LED driving circuit, which includes a rectifying circuit, a first switching tube Q1, an inductor L1, a first diode D1, an output capacitor C1, and a dimming control circuit 10. In an embodiment of the invention, the first switch Q1, the inductor L1, the first diode D1, and the output capacitor C1 form a Buck-type switch circuit. In other embodiments, other topologies may be derived, as known to those skilled in the art. As shown in fig. 2, the rectifying circuit receives an input voltage Vin, and converts the input voltage Vin of an alternating current into a direct current bus voltage. A first terminal of the first switch Q1 is coupled to the rectifying circuit, a second terminal of the first switch Q1 is coupled to the first terminal of the inductor L1, and a control terminal of the first switch Q1 is coupled to the dimming control circuit 10. The first switching transistor Q1 may be a Field Effect Transistor (FET) or a bipolar transistor (BJT). In an embodiment of the invention, the first switching transistor Q1 is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), a drain terminal of the first switching transistor Q1 is coupled to the rectifying circuit, a source terminal of the first switching transistor Q1 is coupled to the first terminal of the inductor L1, and a gate terminal of the first switching transistor Q1 is coupled to the dimming control circuit 10. As shown in fig. 2, a cathode terminal of the first diode D1 is coupled to the second terminal of the first switch Q1, and an anode terminal of the first diode D1 is coupled to the input ground. The first terminal of the inductor L1 is coupled to the floating ground terminal, the second terminal of the inductor L1 is coupled to the first terminal of the output capacitor C1, the second terminal of the output capacitor C1 is coupled to the input ground terminal, and the LED lamp is connected in parallel to the output capacitor C1. In an embodiment of the invention, a first resistor R1 is further coupled between the first switch Q1 and the inductor L1. The first resistor R1 is a sampling resistor, the current sampling terminal of the driving control circuit 12 is coupled to the first resistor R1, and the driving control circuit 12 can obtain the current flowing through the inductor L1 by sampling and control the switching state of the first switching tube Q1 according to the sampling current, thereby implementing the constant current control of the LED driving circuit.
In an embodiment of the present invention, the dimming control circuit 10 includes a logic level converting circuit 11 and a driving control circuit 12. The input terminal of the logic level converting circuit 11 receives the first dimming signal PWM1 from the signal transmitting module 20, the reference ground of the logic level converting circuit 11 is an input ground, and the logic level converting circuit 11 is configured to receive the first dimming signal PWM1 and output the second dimming signal PWM2 through a level conversion process. Since the reference ground of the driving control circuit 12 is a floating ground, the reference ground of the signal transmitting module 20 is an input ground, and the driving control circuit 12 is different from the reference ground of the signal transmitting module 20 generating the first dimming signal PWM1, the driving control circuit 12 cannot directly recognize the first dimming signal PWM 1. The level conversion process is to convert the first dimming signal PWM1, which is referenced to the ground as the input ground, into the second dimming signal PWM2, which is referenced to the ground as the floating ground, so that the driving control circuit 12 can recognize the second dimming signal PWM2, thereby implementing dimming control of the LED driving circuit according to the second dimming signal PWM 2. The input terminal of the driving control circuit 12 is coupled to the output terminal of the logic level converting circuit 11, the reference ground of the driving control circuit 12 is a floating ground, and the driving control circuit 12 is configured to control the switching state of the first switch Q1 according to the second dimming signal PWM2 to implement dimming control. According to the dimming control circuit and the LED drive circuit thereof, the current flowing through the inductor L1 can be acquired, and the current flowing through the inductor L1 is consistent with the current flowing through an LED lamp, so that the sampling current can directly represent the output current of the LED drive circuit, and no redundant error is introduced in the middle. In addition, the reference ground of the driving control circuit 12 is a floating ground, and the reference grounds of other circuits are input grounds, so that electrical isolation can be effectively realized, the constant current driving control of the LED driving circuit is not interfered, and the LED constant current driving control precision is far higher than that of the prior art.
In an embodiment of the invention, a current sampling terminal of the dimming control circuit is coupled to a first terminal of the first resistor, and a second terminal of the first resistor is coupled to a first terminal of the inductor.
In an embodiment of the invention, when the signal sending module 20 does not send the first dimming signal PWM1 or the first dimming signal PWM1 sent by the signal sending module 20 is always in an inactive state (low state), the driving control circuit 12 controls the LED driving circuit to keep constant current output at a predetermined output current Io. When the first dimming signal PWM1 sent by the signal sending module 20 is in an active state (may be a PWM signal with high and low levels switched), the logic level conversion circuit 11 receives the first dimming signal PWM1 and outputs the second dimming signal PWM2 through a level conversion process, the driving control circuit 12 adjusts the output current of the LED driving circuit to the required output current Io 'according to the second dimming signal PWM2, and when the signal sending module does not send a signal for dimming again, the LED driving circuit keeps outputting a constant current at the output current Io', thereby implementing dimming control of the LED driving circuit. In an embodiment of the present invention, the dimming control circuit 10 can realize the LED dimming control with different dimming depth requirements.
In an embodiment of the present invention, as shown in fig. 3, the dimming control circuit 10 includes a logic level converting circuit 11 and a driving control circuit 12. The ground GND of the driving control circuit 12 is coupled to the floating terminal, the floating terminal is coupled to the first terminal of the inductor L1, and the second terminal of the inductor L1 is coupled to the output terminal of the LED driving circuit. In an embodiment of the invention, the high voltage input terminal of the driving control circuit 12 is coupled to a dc bus of the LED driving circuit. In an embodiment, the first switch Q1 is a transistor MOSFET, and the high voltage input terminal of the driving control circuit 12 is specifically a Drain terminal Drain. In an embodiment of the present invention, the power supply terminal VDD of the driving control circuit 12 is coupled to the floating terminal through a second capacitor C2. The driving control circuit 12 controls the switching state of the first switching tube Q1 according to the sampling current to realize the constant current output of the LED driving circuit.
In an embodiment of the invention, the logic level converting circuit and the driving control circuit are packaged in the same package, which can simplify the circuit layout and save unnecessary circuit pins. In another embodiment of the present invention, the logic level converting circuit and the driving control circuit are respectively packaged in respective packages, and the package of the logic level converting circuit and the package of the driving control circuit form the dimming control circuit.
In an embodiment of the present invention, the dimming control circuit 10 further includes a first switch Q1, and when the circuit devices in the dimming control circuit 10 are packaged in the same package, the pins of the package need to be adjusted accordingly. In an embodiment of the present invention, the dimming control circuit 10 further includes a first resistor R1. In an embodiment of the present invention, the dimming control circuit 10 further includes a second capacitor C2.
In an embodiment of the present invention, the dimming control circuit 12 further includes a signal sending module 20, an input end of the signal sending module 20 receives a control signal from a user terminal, an output end of the signal sending module 20 is coupled to the input end of the logic level converting circuit 11, and the signal sending module 20 is configured to convert the control signal from the user terminal into the first dimming signal PWM 1. In a specific embodiment, the signal sending module 20 may be a wireless signal sending module such as a wifi module circuit, a bluetooth module circuit, or a wired signal sending module, and the reference ground of the signal sending module 20 is coupled to the input ground. In an embodiment of the present invention, the signal sending module 20 is further coupled to a power circuit for supplying power thereto.
In an embodiment of the invention, as shown in fig. 4, the logic level converting circuit 11 includes a not gate, a second switch Q2, a second resistor R2, a third resistor R3, and a second diode D2. The input terminal of the not-gate receives the first dimming signal PWM 1. The control terminal of the second switch Q2 is coupled to the output terminal of the not gate, and the second terminal of the second switch Q2 is coupled to the input ground. A first terminal of the second resistor R2 is coupled to the first voltage VDD. The first terminal of the third resistor R3 is coupled to the second terminal of the second resistor R2, and the second terminal of the third resistor R3 is coupled to the first terminal of the second switch Q2. A cathode terminal of the second diode D2 is coupled to the second terminal of the second resistor R2, an anode terminal of the second diode D2 is coupled to the floating terminal, and a cathode terminal of the second diode D2 outputs the second dimming signal PWM 2. When the first dimming signal PWM1 is at a high level, the not gate output is at a low level, the second switch Q2 is turned off, and the second dimming signal PWM2 output by the logic level converting circuit 11 is at a first level. When the first dimming signal PWM1 is at a low level, the not gate output is at a high level, the second switch Q2 is turned on, and the second dimming signal PWM2 output by the logic level converting circuit 11 is at a second level. The first level is high level and the second level is low level. The first dimming signal PWM1, which is referenced to the ground as the input ground, may be converted into the second dimming signal PWM2, which is referenced to the ground as the floating ground, through a level conversion process of the logic level conversion circuit 11.
In an embodiment of the present invention, as shown in fig. 5, the logic level shift circuit 11 includes a rising edge obtaining circuit 111, a falling edge obtaining circuit 112, and a trigger circuit 113, and the reference ground of the logic level shift circuit 11 is an input ground. The input terminal of the rising edge obtaining circuit 111 receives the first dimming signal PWM1, and the rising edge obtaining circuit 111 is used for obtaining the rising edge of the first dimming signal PWM 1. The input terminal of the falling edge obtaining circuit 112 receives the first dimming signal PWM1, and the falling edge obtaining circuit 112 is configured to obtain the falling edge of the first dimming signal PWM 1. The set terminal of the trigger circuit 113 is coupled to the output terminal of the rising edge obtaining circuit 111, the reset terminal of the trigger circuit 113 is coupled to the output terminal of the falling edge obtaining circuit 112, and the ground terminal of the trigger circuit 113 is coupled to the floating terminal. The trigger circuit 113 is configured to generate the second dimming signal PWM2 according to the output signal of the rising edge obtaining circuit and the output signal of the falling edge obtaining circuit. The first dimming signal PWM1 with reference to ground as input ground can be converted into the second dimming signal PWM2 with reference to ground as floating ground by the logic level converting circuit 11.
As shown in fig. 6, an embodiment of the present invention discloses an LED driving circuit, which includes a rectifying circuit, a first switching tube Q1, an inductor L1, a first diode D1, an output capacitor C1, and a dimming control circuit 10. In an embodiment of the invention, the first switch Q1, the inductor L1, the first diode D1, and the output capacitor C1 form a Buck-type switch circuit. The drain terminal of the first switching tube Q1 is coupled to the rectifying circuit, the source terminal of the first switching tube Q1 is coupled to the first terminal of the inductor L1, and the gate terminal of the first switching tube Q1 is coupled to the dimming control circuit 10. As shown in fig. 6, a cathode terminal of the first diode D1 is coupled to the second terminal of the first switch Q1, and an anode terminal of the first diode D1 is coupled to the input ground. The first terminal of the inductor L1 is coupled to the floating terminal, the second terminal of the inductor L1 is coupled to the first terminal of the output capacitor C1, the second terminal of the output capacitor C1 is coupled to the first resistor R1, and the LED lamp is connected in parallel to the output capacitor C1. In an embodiment of the invention, the current sampling terminal of the logic level converting circuit 11 is coupled to the first terminal of the first resistor R1, the second terminal of the first resistor R1 is coupled to the input ground, and the first resistor R1 is a sampling resistor. The logic level conversion circuit 11 may obtain the current flowing through the inductor L1 through sampling and control the switching state of the first switching tube Q1 according to the sampled current, thereby implementing constant current control of the LED driving circuit.
As shown in fig. 6, in an embodiment of the present invention, the dimming control circuit 10 includes a logic level converting circuit 11 and a driving control circuit 12. The input terminal of the logic level converting circuit 11 receives the first dimming signal PWM1 from the signal transmitting module 20, the reference ground of the logic level converting circuit 11 is an input ground, and the logic level converting circuit 11 is configured to receive the first dimming signal PWM1 and output the second dimming signal PWM2 through a level conversion process. Since the reference ground of the driving control circuit 12 is a floating ground, the reference ground of the signal transmitting module 20 is an input ground, and the driving control circuit 12 is different from the reference ground of the signal transmitting module 20 generating the first dimming signal PWM1, the driving control circuit 12 cannot directly recognize the first dimming signal PWM 1. The level conversion process is to convert the first dimming signal PWM1, which is referenced to the ground as the input ground, into the second dimming signal PWM2, which is referenced to the ground as the floating ground, so that the driving control circuit 12 can recognize the second dimming signal PWM2, thereby implementing dimming control of the LED driving circuit according to the second dimming signal PWM 2. In another embodiment of the present invention, the logic level converting circuit 11 generates a third dimming signal according to the received first dimming signal PWM1 and the sampling current, and the third dimming signal is a signal based on the reference ground as the input ground, so the logic level converting circuit 11 further outputs the third dimming signal through logic level conversion to the second dimming signal PWM2, the second dimming signal PWM2 is a signal based on the reference ground as the floating ground, and in this embodiment, the second dimming signal PWM2 is a driving control signal of the first switch tube. The input terminal of the driving control circuit 12 is coupled to the output terminal of the logic level converting circuit 11, the reference ground of the driving control circuit 12 is a floating ground, and the driving control circuit 12 is configured to drive the first switch Q1 according to the second dimming signal PWM2 to implement dimming control.
The embodiment of the invention discloses an LED driving circuit which comprises a rectifying circuit, a first switching tube, an inductor, a first diode, an output capacitor and the dimming control circuit.
As shown in fig. 7, an embodiment of the invention discloses a dimming control method for an LED driving circuit. The LED driving circuit comprises a dimming control circuit, the dimming control circuit controls the on-off state of a first switching tube in the LED driving circuit according to the sampling current so as to realize constant current output of the LED driving circuit, and the sampling current represents the current flowing through an inductor in the LED driving circuit.
The dimming control method comprises the following steps:
s100, receiving a first dimming signal from a signal sending module; the first dimming signal is a signal based on a reference ground as an input ground;
s200, converting a first dimming signal with reference ground as an input ground into a second dimming signal with reference ground as a floating ground; and
and S300, controlling the on-off state of a first switching tube in the LED driving circuit according to the second dimming signal to realize dimming control.
In an embodiment of the present invention, the dimming control method includes the steps of: the logic level conversion circuit receives a first dimming signal PWM1 from the signal sending module; the logic level conversion circuit converts the first dimming signal PWM1 with reference to the ground as the input ground into the second dimming signal PWM2 with reference to the ground as the floating ground; the driving control circuit controls the switching state of the first switch tube in the LED driving circuit according to the second dimming signal PWM2 to realize dimming control.
In an embodiment of the present invention, before the step of receiving the first dimming signal from the signal transmitting module, the method further includes the steps of: the control signal from the user terminal is received and converted into the first dimming signal PWM 1.
In an embodiment of the present invention, before the step of receiving the first dimming signal from the signal transmitting module, the method further includes the steps of: the signal sending module receives the control signal from the user terminal and converts the control signal of the user terminal into a first dimming signal PWM 1.
The invention provides a dimming control circuit, a dimming control method and an LED drive circuit, wherein the dimming control circuit comprises a logic level conversion circuit and a drive control circuit. The current sampling terminal of the dimming control circuit is coupled to an inductor in the LED driving circuit to sample the current flowing through the inductor. The dimming control circuit controls the on-off state of a first switching tube in the LED driving circuit according to the sampling current so as to realize constant current output of the LED driving circuit, and the sampling current represents the current flowing through an inductor in the LED driving circuit. According to the dimming control circuit, the dimming control method and the LED drive circuit, the current flowing through the inductor can be collected, and the current flowing through the inductor is consistent with the current flowing through the LED lamp, so that the sampling current can directly represent the output current of the LED drive circuit, no redundant error is introduced in the middle, and the LED constant current control precision is far higher than that of the prior art. In addition, the first dimming signal with reference ground as the input ground is converted into the second dimming signal with reference ground as the floating ground through the logic level conversion circuit, and the problem of control signal transmission of a non-common ground circuit in the LED driving circuit is effectively solved.
The above description and applications of the invention herein are illustrative and are not intended to limit the scope of the invention to the above described embodiments. The descriptions related to the effects or advantages mentioned in the embodiments may not be reflected in the experimental examples due to the uncertainty of the specific condition parameters, and are not used for limiting the embodiments. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (14)
1. A dimming control circuit for an LED drive circuit is characterized in that a current sampling end of the dimming control circuit is coupled with an inductor in the LED drive circuit, the dimming control circuit controls the on-off state of a first switching tube in the LED drive circuit according to a sampling current so as to realize constant current output of the LED drive circuit, and the sampling current represents the current flowing through the inductor; the dimming control circuit comprises:
the input end of the logic level conversion circuit receives a first dimming signal from the signal sending module, the reference ground of the logic level conversion circuit is input ground, and the logic level conversion circuit is used for receiving the first dimming signal and outputting a second dimming signal through a level conversion process; the first dimming signal is a signal based on a reference ground as an input ground; and
the input end of the driving control circuit is coupled with the logic level conversion circuit, the reference ground of the driving control circuit is a floating ground, and the driving control circuit is used for controlling the switching state of the first switching tube according to the second dimming signal so as to realize dimming control; the level conversion process is to convert a first dimming signal with reference to the ground as the input ground into a second dimming signal with reference to the ground as the floating ground.
2. The dimming control circuit of claim 1, wherein a ground terminal of the driving control circuit is coupled to a floating terminal, the floating terminal is coupled to a first terminal of the inductor, and a second terminal of the inductor is coupled to an output terminal of the LED driving circuit.
3. The dimming control circuit of claim 1, wherein the high voltage input of the drive control circuit is coupled to a dc bus of the LED driver circuit.
4. The dimming control circuit of claim 1, wherein the supply terminal of the drive control circuit is coupled to a floating terminal through a second capacitor.
5. The dimming control circuit of claim 1, further comprising:
the input end of the signal sending module receives a control signal from a user end, and the output end of the signal sending module is coupled with the logic level conversion circuit and used for converting the control signal of the user end into a first dimming signal.
6. The dimming control circuit of claim 1, wherein the logic level conversion circuit comprises:
a NOT gate, an input end of which receives the first dimming signal;
a control terminal of the second switch tube is coupled to the not gate, and a second terminal of the second switch tube is coupled to the input ground;
a first end of the second resistor is coupled with a first voltage;
a third resistor, a first end of which is coupled to the second end of the second resistor, and a second end of which is coupled to the first end of the second switch tube; and
a cathode of the second diode is coupled to the second end of the second resistor, an anode of the second diode is coupled to the floating ground, and a cathode of the second diode outputs the second dimming signal.
7. The dimming control circuit of claim 1, wherein the logic level conversion circuit comprises:
a rising edge obtaining circuit, an input end of which receives the first dimming signal, for obtaining a rising edge of the first dimming signal;
a falling edge obtaining circuit, an input end of which receives the first dimming signal, for obtaining a falling edge of the first dimming signal; and
and the trigger circuit is coupled with the rising edge acquisition circuit at a set end, coupled with the falling edge acquisition circuit at a reset end, and coupled with the floating end at a ground end, and is used for generating the second dimming signal according to signals sent by the rising edge acquisition circuit and the falling edge acquisition circuit.
8. The dimming control circuit of claim 1, wherein the current sampling terminal of the driving control circuit is coupled to a first terminal of a first resistor, and a second terminal of the first resistor is coupled to a floating terminal.
9. The dimming control circuit of claim 1, wherein the current sampling terminal of the logic level shifting circuit is coupled to a first terminal of a first resistor, and a second terminal of the first resistor is coupled to the input ground.
10. The dimming control circuit of any of claims 1-9, wherein the logic level conversion circuit and the driving control circuit are packaged in the same package.
11. An LED driving circuit, comprising a rectifying circuit, a first switch tube, an inductor, a first diode, an output capacitor, and the dimming control circuit as claimed in any one of claims 1 to 9.
12. The LED driving circuit as claimed in claim 11, wherein the first switch tube, the inductor, the first diode, and the output capacitor form a Buck-type switch circuit, a first resistor is further coupled between the first switch tube and the inductor, a first end of the inductor is coupled to a floating ground, and a second end of the inductor is coupled to an output terminal of the LED driving circuit.
13. The LED driving circuit of claim 12, wherein the current sampling terminal of the dimming control circuit is coupled to a first terminal of a first resistor, and a second terminal of the first resistor is coupled to a first terminal of an inductor.
14. A dimming control method for an LED drive circuit is characterized in that the LED drive circuit comprises a dimming control circuit, the dimming control circuit controls the on-off state of a first switching tube in the LED drive circuit according to a sampling current to realize the constant current output of the LED drive circuit, and the sampling current represents the current flowing through an inductor in the LED drive circuit; the dimming control method comprises the following steps:
receiving a first dimming signal from a signal sending module; the first dimming signal is a signal based on a reference ground as an input ground;
converting a first dimming signal with reference to the ground as an input ground into a second dimming signal with reference to the ground as a floating ground; and
and controlling the on-off state of a first switching tube in the LED driving circuit according to the second dimming signal to realize dimming control.
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Application publication date: 20201117 |