CN114629353B - High-power driving circuit - Google Patents

High-power driving circuit Download PDF

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CN114629353B
CN114629353B CN202210516983.9A CN202210516983A CN114629353B CN 114629353 B CN114629353 B CN 114629353B CN 202210516983 A CN202210516983 A CN 202210516983A CN 114629353 B CN114629353 B CN 114629353B
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signal
controllable switch
voltage
resistor
unit
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CN114629353A (en
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不公告发明人
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Suzhou Baker Microelectronics Co Ltd
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Suzhou Baker Microelectronics Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/32—Pulse-control circuits
    • H05B45/325—Pulse-width modulation [PWM]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/30—Driver circuits
    • H05B45/37—Converter circuits
    • H05B45/3725—Switched mode power supply [SMPS]

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Electronic Switches (AREA)

Abstract

The invention discloses a high-power drive circuit, comprising: the circuit comprises an inductor, a first controllable switch, a second controllable switch, a sampling circuit and a control module; the inductor is connected with the element to be driven in series to form a first series circuit, the first end of the first series circuit is connected with a power supply, the second end of the first series circuit is grounded after being connected with the first controllable switch in series, and the second end of the first series circuit is also connected with the first end of the first series circuit through the second controllable switch; the sampling circuit is respectively connected with the first series circuit and the control module and is used for acquiring current information on the first series circuit to obtain a sampling signal; the control module is also respectively connected with the controlled end of the first controllable switch and the controlled end of the second controllable switch, and is used for controlling the on-off of the first controllable switch and the second controllable switch according to the sampling signal, and when one of the first controllable switch and the second controllable switch is in an on state, the other one of the first controllable switch and the second controllable switch is in an off state. The invention can greatly improve the power of the driving circuit.

Description

High-power driving circuit
Technical Field
The invention relates to the technical field of LED driving, in particular to a high-power driving circuit.
Background
In recent years, with the development of Light Emitting Diode (LED) technology, high power LEDs are widely used, and thus, the demand for driving circuits of the high power LEDs is also increasing.
However, the power of the current LED driving circuit is generally low and difficult to increase, and the driving requirement of high power cannot be met.
Disclosure of Invention
In view of this, embodiments of the present invention provide a high power driving circuit to solve the problem that the power of the conventional driving circuit is generally low.
An embodiment of the present invention provides a high power driving circuit, including: the circuit comprises an inductor, a first controllable switch, a second controllable switch, a sampling circuit and a control module;
the inductor is connected with an element to be driven in series to form a first series circuit, a first end of the first series circuit is connected with a power supply, a second end of the first series circuit is connected with the first controllable switch in series and then grounded, and the second end of the first series circuit is also connected with the first end of the first series circuit through the second controllable switch;
the sampling circuit is respectively connected with the first series circuit and the control module and is used for collecting current information on the first series circuit and inputting a collected sampling signal to the control module;
the control module is further connected with the controlled end of the first controllable switch and the controlled end of the second controllable switch respectively, and is used for controlling the on-off of the first controllable switch and the second controllable switch according to the sampling signal, and when one of the first controllable switch and the second controllable switch is in an on state, the other one of the first controllable switch and the second controllable switch is in an off state.
Optionally, the second controllable switch is an N-channel MOS transistor including a body diode, and the body diode is configured to form a closed freewheeling loop with the first series circuit when the first controllable switch and the second controllable switch are both in an off state.
Optionally, the control module further receives an adjustment signal, and controls on/off of the first controllable switch and the second controllable switch according to the adjustment signal and the sampling signal.
Optionally, the high-power driving circuit further includes: a voltage holding circuit;
the voltage holding circuit includes: a first capacitor;
the controlled end of the second controllable switch is connected with the first end of the second controllable switch through the first capacitor, and the controlled end of the second controllable switch is also connected with a first voltage; a first end of the second controllable switch is an end connected to a second end of the first series circuit;
the first voltage is greater than or equal to a preset threshold value, and the preset threshold value is a minimum voltage difference between a controlled end and a first end of the second controllable switch, which can enable the second controllable switch to be conducted.
Optionally, the control module includes a first logic module;
the first logic module is used for outputting a first control signal and a second control signal according to the sampling signal and the received regulating signal; the first control signal and the second control signal are respectively used for controlling the on-off of the first controllable switch and the on-off of the second controllable switch.
Optionally, the sampling circuit includes a first resistor connected in series with the first series circuit;
the first logic module comprises a sampling unit, a first comparison unit and a control unit;
the sampling unit is used for acquiring a voltage difference between two ends of the first resistor to serve as the sampling signal and generating a first voltage signal based on the voltage difference;
the first comparing unit is configured to compare the first voltage signal with a second voltage signal to obtain a comparison result signal, where the second voltage signal is obtained based on the adjustment signal;
the control unit is used for outputting the first control signal and the second control signal based on the comparison result signal.
Optionally, the sampling unit includes a second resistor, a third resistor, and a third controllable switch;
the second resistor and the third resistor are connected in series to form a second series circuit, and the input of the second series circuit is an electric signal obtained based on the voltage difference;
the third controllable switch is connected with the third resistor in parallel, and when the third controllable switch is switched on, the third resistor is short-circuited;
and the control unit outputs a control signal for controlling the on-off of the third controllable switch according to the first control signal and/or the second control signal output by the control unit.
Optionally, the sampling unit further includes a fourth resistor, a fifth resistor, a first switch tube, a second switch tube, an isolation switch, a first current source, and a second current source;
one end of the fifth resistor is connected with the first end of the first resistor, one end of the fourth resistor is connected with the second end of the first resistor, the other end of the fifth resistor, the first switch tube and the first current source are sequentially connected in series and then grounded, the other end of the fourth resistor, the second switch tube and the second current source are sequentially connected in series and then grounded, and the other end of the fifth resistor is also connected in series with the second series circuit through the isolating switch and then grounded;
the first end of the first resistor is connected with the output end of the power supply; the fourth resistor and the fifth resistor have the same resistance value, the first current source and the second current source output the same current value, the second series circuit has the current value equal to the difference between the current of the fifth resistor and the current of the fourth resistor, and the first switch tube and the second switch tube are triodes or MOS tubes.
Optionally, the first switch tube and the second switch tube are PNP-type triodes, an emitter of the first switch tube is connected to the other end of the fifth resistor, a collector of the first switch tube is connected to the first current source, and a base and the collector of the first switch tube are connected to the first current source; and the emitting electrode of the second switch tube is connected with the other end of the fourth resistor, the collector electrode of the second switch tube is connected with the second current source, and the base electrode of the second switch tube is connected with the base electrode of the first switch tube.
Optionally, the first logic module further includes an adjusting unit; the adjusting signal is a linear adjusting signal or a pulse adjusting signal;
the adjusting unit is used for receiving the linear adjusting signal and outputting a corresponding second voltage signal according to the linear adjusting signal; or,
the regulating unit is used for receiving the pulse regulating signal and outputting a control signal for controlling the first series circuit to be connected or disconnected and a second voltage signal according to the pulse regulating signal; when the first series circuit is conducted, the second voltage signal output by the adjusting unit is a voltage signal with a first preset voltage value, and the first preset voltage value is a preset fixed voltage value;
the first logic module outputs the first control signal and the second control signal according to the second voltage signal and the sampling signal.
Optionally, the adjusting unit includes a sixth resistor, a second comparing unit, a third comparing unit, and a fourth controllable switch;
a first end of the sixth resistor is configured to receive the adjustment signal, a second end of the sixth resistor is connected to one input end of the second comparing unit and one input end of the third comparing unit, the second end of the sixth resistor is also grounded through the fourth controllable switch, another input end of the second comparing unit is connected to the voltage signal with the first preset voltage value, an output end of the second comparing unit is connected to a controlled end of the fourth controllable switch, and another input end of the third comparing unit is connected to the voltage signal with the second preset voltage value; the first preset voltage value is greater than the second preset voltage value;
when the adjusting signal is a linear adjusting signal of which the voltage value is greater than the second preset voltage value and less than the first preset voltage value, the second comparing unit outputs a control signal for controlling the fourth controllable switch to be switched off, and the third comparing unit outputs a control signal for controlling the first series circuit to be switched on; the voltage value of the second voltage signal output by the adjusting unit is equal to the voltage value at the second end of the sixth resistor and equal to the voltage value of the adjusting signal input by the adjusting unit;
when the adjusting signal is a pulse adjusting signal and the pulse adjusting signal is in a low-voltage stage, the second comparing unit outputs a control signal for controlling the fourth controllable switch to be switched off, and the third comparing unit outputs a control signal for controlling the first series circuit to be switched off; when the pulse adjusting signal is in a high-voltage stage, the second voltage signal output by the adjusting unit is a voltage signal of the first preset voltage value, and the third comparing unit outputs a control signal for controlling the conduction of the first series circuit; the high voltage value of the pulse adjusting signal is greater than the first preset voltage value, and the low voltage value of the pulse adjusting signal is less than the second preset voltage value.
Optionally, when the adjustment signal is the pulse adjustment signal and is in a high-voltage stage, the sixth resistor, the second comparing unit, and the fourth controllable switch form a negative feedback circuit, when the negative feedback circuit reaches a steady state, a voltage at a positive input end of the second comparing unit is equal to a voltage at a negative input end of the second comparing unit and is equal to the first preset voltage value, and a voltage value of the second voltage signal output by the adjusting unit is equal to a voltage at a positive input end of the second comparing unit.
Optionally, the adjusting unit further includes a voltage following unit, an input end of the voltage following unit is connected to the second end of the sixth resistor, and an output end of the voltage following unit is used as an output end of the adjusting unit.
In the high-power driving circuit provided by the embodiment of the invention, the power supply supplies power to the inductor for storing energy when the first controllable switch is switched on and the second controllable switch is switched off, the current on the element to be driven is the inductor energy storage current at the moment, the current on the inductor is increased, when the first controllable switch is switched off and the second controllable switch is switched on, the inductor releases energy through the second controllable switch, the current on the element to be driven is the inductor energy release current at the moment, and the current on the inductor is reduced. Therefore, due to the existence of the second controllable switch, the follow current can reach a large value, and the power of the driving circuit is greatly improved.
Drawings
The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are schematic and are not to be understood as limiting the invention in any way, and in which:
fig. 1 is a schematic diagram of an overall circuit structure of a high-power driving circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a power circuit structure of a high-power driving circuit according to an embodiment of the present invention;
FIG. 3 is a schematic block diagram of a control module of a high power driving circuit according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a first logic module in a control module of a high power driver circuit according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a current waveform in an inductor of a high power driving circuit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
It should be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of other like elements in a process, method, article, or apparatus comprising the element. The term "connected" may be directly connected or indirectly connected, and the term "indirectly connected" means that other elements or components exist between the two. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate a number of the indicated technical features. In the description of the following examples, "plurality" means two or more unless specifically limited otherwise.
Referring to fig. 1, an embodiment of the invention provides a high power driving circuit, including: the circuit comprises an inductor L1, a first controllable switch M1, a second controllable switch M2, a sampling circuit and a control module;
the inductor L1 and an element to be driven are connected in series to form a first series circuit, a first end of the first series circuit is connected with a power supply, a second end of the first series circuit is connected with the first controllable switch M1 in series and then grounded, and the second end of the first series circuit is also connected with the first end of the first series circuit through the second controllable switch M2;
the sampling circuit is respectively connected with the first series circuit and the control module and is used for collecting current information on the first series circuit and inputting a collected sampling signal to the control module;
the control module is further connected to the controlled end of the first controllable switch M1 and the controlled end of the second controllable switch M2, respectively, and is configured to control on/off of the first controllable switch M1 and the second controllable switch M2 according to the sampling signal, and when one of the first controllable switch M1 and the second controllable switch M2 is in an on state, the other is in an off state.
The element to be driven may be a Light Emitting Diode (LED). The element to be driven may be one or more. For example, as shown in fig. 1, the driving element may be two LED lamp beads D1, D2 connected in series. The control module may be a control chip X1, please refer to fig. 1, a NSENSE pin of the control chip X1 is a sampling signal input pin, a GATE pin of the control chip X1 is a first driving signal (PWM signal) output pin of the first controllable switch M1 and is connected to a controlled terminal of the first controllable switch M1, and a TOPGATE pin of the control chip X1 is a second driving signal of the second controllable switch M2 (i.e., (a GATE signal) of the second controllable switch M2
Figure 111406DEST_PATH_IMAGE001
Signal) output pin connected with the controlled terminal of the second controllable switch M2. The first controllable switch M1 is a drive circuit main switch and the second controllable switch M2 is a drive circuit freewheeling switch. The first controllable switch M1 and the second controllable switch M2 may be field effect (MOS) transistors, triodes, or other controlled switches. One of the first and second controllable switches M1, M2 necessarily needs to be in the off state while the other is in the on state.
Referring to fig. 2, the working principle and the working process of the high power driving circuit according to the embodiment of the invention are as follows:
it should be noted that, the PWM signal is the driving signal of the first controllable switch M1,
Figure 845007DEST_PATH_IMAGE001
the signals are the drive signal of the second controllable switch M2, the PWM signal and
Figure 129358DEST_PATH_IMAGE001
the signal is provided by the control chip X1, the first controllable switch M1 and the second controllable switch M2 may be N-channel MOS transistors, the first controllable switch M1 may also be referred to as a main MOS transistor or a main power MOS transistor, and the second controllable switch M2 may also be referred to as a freewheeling MOS transistor. When the PWM signal is high,
Figure 479568DEST_PATH_IMAGE001
The signal is low, so that the first controllable switch M1 is switched on, the second controllable switch M2 is switched off, the power supply VIN stores energy for the inductor L1 at the moment to form a VIN-R1-D1-D2-L1-M1-GND-VIN current loop, the current on the LED lamp beads D1 and D2 is the energy storage current of the inductor L1 at the moment, and the current of the inductor L1 is increased; when the PWM signal is low, the PWM signal is,
Figure 439390DEST_PATH_IMAGE001
the signal is high, therefore, the first controllable switch M1 is turned off, the second controllable switch M2 is turned on, the inductor L1 releases energy through the second controllable switch M2 to form a current loop of R1-D1-D2-L1-M2-R1, at the moment, the currents on the LED lamp beads D1 and D2 are inductor energy releasing currents, and the inductor currents are reduced, so that the follow current can reach a large value due to the existence of the second controllable switch M2, and the power of the driving circuit is greatly improved.
In the embodiment of the invention, when the first controllable switch M1 is turned on and the second controllable switch M2 is turned off, the power supply supplies power to the inductor L1 to store energy, at this time, the current on the element to be driven is the inductor energy storage current, the current on the inductor L1 is increased, when the first controllable switch M1 is turned off and the second controllable switch M2 is turned on, the inductor L1 releases energy through the second controllable switch M2, at this time, the current on the element to be driven is the inductor energy release current, and the current on the inductor L1 is reduced. Therefore, the freewheeling current can reach a large value due to the presence of the second controllable switch M2, thereby greatly increasing the power of the driving circuit.
In some optional specific embodiments, the second controllable switch M2 is an N-channel MOS transistor including a body diode, and the body diode is configured to form a closed freewheeling loop with the first series circuit when both the first controllable switch M1 and the second controllable switch M2 are in an open state.
In the embodiment of the present invention, in order to prevent the circuit from being damaged by direct grounding of the power supply due to the simultaneous conduction of the first controllable switch M1 and the second controllable switch M2, the PWM signals and
Figure 558656DEST_PATH_IMAGE001
setting dead time between signals, i.e. a period of time after the PWM signal is changed from high to low, and then controlling
Figure 686012DEST_PATH_IMAGE002
The signal changes from low to high, and, for the same reason,
Figure 523518DEST_PATH_IMAGE002
after the signal changes from high to low for a period of time, the PWM signal is controlled to change from low to high, so that the first controllable switch M1 is switched off for a period of time, then the second controllable switch M2 is controlled to be switched on, and the second controllable switch M2 is switched off for a period of time, then the first controllable switch M1 is controlled to be switched on. In the dead time after the first controllable switch M1 is turned off (at this time, the second controllable switch M2 is not turned on), the inductor L1 may realize a freewheeling through the body diode due to the presence of the body diode of the MOS transistor as the second controllable switch M2. Specifically, when the first controllable switch M1 is turned on, the voltage at the connection point between the inductor L1 and the first controllable switch M1, that is, the anode voltage of the body diode of the second controllable switch M2 is very small and is approximately grounded, and the cathode of the body diode of the second controllable switch M2 is connected to the power supply VIN, and the voltage is relatively high, so that when the first controllable switch M1 is turned on, the body diode of the second controllable switch M2 is reversely cut off; after the first controllable switch M1 is turned off, the inductor L1 and the second controllable switch L1 are enabled to follow current due to the effect of the inductorThe voltage at the junction of one controllable switch M1, i.e. the anode voltage of the body diode of the second controllable switch M2, rises above the supply source VIN, thus turning on the freewheeling.
In other optional specific embodiments, the control module further receives an adjustment signal, and controls on/off of the first controllable switch M1 and the second controllable switch M2 according to the adjustment signal and the sampling signal. And the control chip X1, namely an AD pin of the control module is an input pin of the adjusting signal.
The adjusting signal may be a dimming signal, and in this case, the element to be driven may be a light emitting diode. That is to say, in the embodiment of the present invention, the control module needs to control the first controllable switch M1 and the second controllable switch M2 according to the sampling signal, and also needs to control the first controllable switch M1 and the second controllable switch M2 according to the received adjustment signal. The adjustment signal may be a voltage signal input by the dimmer.
In some optional embodiments, the high power driving circuit further includes: a voltage holding circuit;
the voltage holding circuit includes: a first capacitor C3;
the controlled end of the second controllable switch M2 is connected to the first end of the second controllable switch M2 through the first capacitor C3, and the controlled end of the second controllable switch M2 is further connected to a first voltage; a first end of the second controllable switch M2 is an end connected to a second end of the first series circuit;
the first voltage is greater than or equal to a preset threshold, and the preset threshold is a minimum voltage difference between the controlled end and the first end of the second controllable switch M2, which can enable the second controllable switch M2 to be turned on.
Specifically, the second controllable switch M2 may be an N-channel MOS transistor, a gate of the N-channel MOS transistor is a controlled terminal of the second controllable switch M2, a source of the N-channel MOS transistor is connected to the second terminal of the first series circuit as one terminal of the second controllable switch M2, and a drain of the N-channel MOS transistor is connected to the first terminal of the first series circuit as the other terminal of the second controllable switch M2. Of said second controllable switch M2The controlled terminal is connected to the first capacitor C3 and the first voltage through a first driving circuit, and the first driving circuit forms a second driving signal (i.e. a second driving signal for driving the second controllable switch M2) by taking the voltage on the first capacitor C3 plus the first voltage as a supply voltage
Figure 27312DEST_PATH_IMAGE002
). The power supply input end of the first driving circuit is connected with a BOOST pin of the control module, the BOOST pin of the control module is connected with the source electrode of the second controllable switch M2 through the first capacitor C3, and the BOOST pin of the control module is further connected with a first voltage.
In the embodiment of the present invention, when the inductor L1 releases energy through the N-channel MOS transistor (i.e. the freewheeling MOS transistor) as the second controllable switch M2, the current on the inductor L1 decreases, the source voltage of the second controllable switch M2 increases, however, one of the conduction conditions of the second controllable switch M2 is that the gate voltage of the second controllable switch M2 is greater than the source voltage and reaches a threshold (i.e. the above-mentioned preset threshold), and the gate voltage of the second controllable switch M2 is provided by the first driving circuit inside the driving circuit control chip X1, so that, at this time, in order to ensure that the second controllable switch M2 is normally conducted, a voltage holding circuit (as shown in fig. 1) composed of a providing circuit of the first voltage (e.g. the INTVCC pin of the control chip X1) and the first capacitor C3 may be provided outside the driving circuit control chip X1, at this time, one end of the first capacitor C3 is connected to the first driving circuit of the second controllable switch M2 inside the control chip X1 through the BOOST pin to provide a gate driving voltage (as shown in fig. 3) for the first driving circuit of the second controllable switch M2 inside the control chip X1, so that the voltage at one end of the first capacitor C3 is related to the gate voltage of the second controllable switch M2, and the other end of the first capacitor C3 is connected to the source of the second controllable switch M2, so that the voltage at the other end of the first capacitor C3 is related to the source voltage of the second controllable switch M2, and therefore, the voltage holding circuit can control the voltages at the two ends of the first capacitor C3 to ensure that the gate voltage of the second controllable switch M2 is greater than the source voltage and the voltage difference between the gate voltage and the source voltage reaches the threshold value, thereby ensuring that the second controllable switch M2 is reliably turned on.
The working process of the voltage holding circuit can be as follows: when the second controllable switch M2 (specifically, an N-channel MOS transistor) is turned off, the first controllable switch M1 (specifically, an N-channel MOS transistor) is turned on, and at this time, the first voltage charges the first capacitor C3, and the voltage of the first capacitor C3 is the first voltage; when the second controllable switch M2 is turned on, the first controllable switch M1 is turned off, and at this time, due to the existence of the first capacitor C3, the voltage of the BOOST pin is raised to the source voltage + the first voltage of the second controllable switch M2, so that it can be ensured that the gate voltage of the second controllable switch M2 is greater than the source voltage and reaches the preset threshold value, thereby ensuring that the second controllable switch M2 is reliably turned on.
In addition, the voltage holding circuit further includes a charging diode D3, an anode of the charging diode D3 is connected to the first voltage providing circuit, for example, the INTVCC pin of the control module, a cathode of the charging diode D3 is connected to the first end of the first capacitor C3, and the first end of the first capacitor C3 is an end connected to the BOOST pin of the control module, so that it is possible to prevent the high voltage on the first capacitor C3 when the first controllable switch M1 turns off the second controllable switch M2 (when the second controllable switch M2 turns on, the source voltage of the second controllable switch M2 is high, and therefore the voltage on the first capacitor C3 is high) from damaging the first voltage providing circuit, for example, a circuit related to the INTVCC pin. The first voltage output by the INTVCC pin may be generated by a second logic module within the control module (i.e., the control chip X1).
In some embodiments, as shown in FIG. 3, the control module includes a first logic module;
the first logic module is used for outputting a first control signal SWON and a second control signal according to the sampling signal and the received regulating signal
Figure 266663DEST_PATH_IMAGE003
(ii) a Wherein the first control signal SWON and the second control signal SWON
Figure 564921DEST_PATH_IMAGE003
Respectively used for controlling the on-off of the first controllable switch M1 and the on-off of the second controllable switch M2.
Specifically, the control module further comprises a first driving circuit and/or a second driving circuit, wherein the first driving circuit is used for amplifying the second control signal based on the supply voltage of the first driving circuit
Figure 952040DEST_PATH_IMAGE003
Deriving a second drive signal for driving said second controllable switch M2 (i.e.
Figure 259524DEST_PATH_IMAGE004
) The second driving circuit is configured to amplify the first control signal SWON based on its supply voltage to obtain a first driving signal (i.e. PWM) for driving the first controllable switch M1.
In addition, as shown in fig. 3, the control module further includes a second logic module, which generates a bandgap reference voltage BG, an internal reference voltage REF and a chip temperature protection signal TSD, wherein the bandgap reference voltage BG may be a voltage signal of a first preset voltage value described below. The second logic module may also generate the first voltage described above, which is output through the INTVCC pin of the control chip X1. In addition, the first voltage is also used as a supply voltage of the second driving circuit.
In some optional specific embodiments, the sampling circuit includes a first resistor R1, and the first resistor R1 is connected in series with the first series circuit;
the first logic module comprises a sampling unit, a first comparison unit U4 and a control unit U5;
the sampling unit is used for acquiring a voltage difference between two ends of the first resistor R1 as the sampling signal and generating a first voltage signal based on the voltage difference;
the first comparing unit U4 is configured to compare the first voltage signal with a second voltage signal to obtain a comparison result signal, where the second voltage signal is obtained based on the adjustment signal;
the control unit U5 is configured to output the first control signal SWON and the second control signal SWON based on the comparison result signal
Figure 87803DEST_PATH_IMAGE003
。
In the embodiment of the present invention, the sampling unit is a voltage sampling circuit of the first resistor R1 (i.e., a sampling resistor), and a voltage difference between two ends of the first resistor R1, i.e., a voltage sampling value, reflects a current magnitude on an element to be driven (e.g., an LED lamp bead). Specifically, the first resistor R1 may be connected in series between the power supply and the first series circuit, that is, one end of the first resistor R1 is connected to the power supply, and the other end is connected to the first series circuit. In addition, in order to collect the follow current, the first resistor R1 should be connected in series to the follow current loop formed by the first series circuit and the second controllable switch M2, and specifically, may be connected in series between the first series circuit and the second controllable switch M2, that is, one end of the first resistor R1 is connected to the first end of the first series circuit, and the other end is connected to the second controllable switch M2 (when the second controllable switch M2 is an N-channel MOS transistor, the other end of the first resistor R1 is connected to a drain of the N-channel MOS transistor), and a connection between the first resistor R1 and the second controllable switch M2 is connected to the power supply.
In summary, in the embodiment of the present invention, since the currents in the LED lamp beads D1 and D2 are the same as the current in the inductor L1, in order to effectively control the currents in the LED lamp beads D1 and D2, the first resistor R1 may be disposed between the positive terminal of D1 and the drain of M2, and the on and off of M1 and M2 are controlled in real time by detecting the voltage difference between the two ends of the first resistor R1, so as to effectively control the currents in the inductor L1, that is, to implement the brightness control of the LED lamp beads D1 and D2.
In other embodiments, the sampling circuit may be other types of circuits as long as an electrical signal reflecting the magnitude or change of the current in the first series circuit can be collected.
In a further alternative specific embodiment, as shown in fig. 4, the sampling unit includes a second resistor R3, a third resistor R4, and a third controllable switch M3;
the second resistor R3 and the third resistor R4 are connected in series to form a second series circuit, and the input of the second series circuit is an electric signal obtained based on the voltage difference;
the third controllable switch M3 is connected in parallel with the third resistor R4, and when the third controllable switch M3 is turned on, the third resistor R4 is short-circuited;
the control unit U5 outputs the first control signal SWON and/or the second control signal according to the control signal
Figure 822541DEST_PATH_IMAGE003
And outputting a control signal for controlling the on-off of the third controllable switch M3.
Referring to the schematic diagram of the current waveform in the inductor L1 shown in fig. 5, during the periods t0-t1 and t2-t3, the PWM signal is high, the first controllable switch M1 is turned on, the second controllable switch M2 is turned off, and the current in the inductor L1 is gradually increased to IH; during t1-t2 and t3-t4, the PWM signal is low, the first controllable switch M1 is turned off, the second controllable switch M2 is turned on, and the inductor L1 current is slowly decreased from IH to IL, i.e. during t0-t1 and t2-t3, the control target of the inductor L1 current is IH, and during t1-t2 and t3-t4, the control target of the inductor L1 current is IL, and at this time, a hysteresis control module must be provided in the sampling unit, so that the current control targets are switched in the same period. The hysteresis control module includes the second resistor R3, the third resistor R4 and the third controllable switch M3.
Specifically, during the periods t0-t1 and t2-t3, when the PWM signal is high, the third controllable switch M3 is turned on at the same time, so as to short-circuit the third resistor R4, and at this time, the first voltage signal V1 output by the sampling unit is smaller than the case of not short-circuiting the third resistor R4, so that the control target current of the control module is increased, because only the current on the first series circuit is increased, the first voltage signal V1 output by the sampling unit is correspondingly increased at this time; conversely, during the periods t1-t2 and t3-t4, when the PWM signal is low, the third controllable switch M3 is turned off at the same time, so that the third resistor R4 is connected to the sampling unit, and the first voltage signal V1 output by the sampling unit is larger than the short-circuited third resistor R4, so that the control target current of the control module is reduced, because only the current on the first serial circuit is reduced, and at this time, the first voltage signal V1 output by the sampling unit is correspondingly reduced.
In the embodiment of the present invention, since the second voltage signal VC for comparing with the first voltage signal V1 is obtained based on the adjustment signal, the second voltage signal VC is unchanged under the condition that the adjustment signal is unchanged, and after the hysteresis control module is arranged, the current control target on the first resistor R1 during t0-t1 and t2-t3 is greater than the current control target on the first resistor R1 during t1-t2 and t3-t 4. Therefore, hysteresis control can be realized through the hysteresis control module, and the control precision of the drive circuit is improved. In addition, by setting the ratio of the second resistor R3 to the third resistor R4, the current ripple on the first series circuit where the element to be driven is located can be conveniently and simply adjusted, so that the current on the element to be driven is smoother.
Of course, the hysteresis control module described above is only a specific form of the hysteresis control module provided in the embodiment of the present invention, but the hysteresis control module is not limited to this structure, and may also be a hysteresis control module with other circuit structures.
As a specific implementation manner, the sampling unit further includes a fourth resistor R5, a fifth resistor R6, a first switch tube Q1, a second switch tube Q2, an isolating switch Q3, a first current source I1, and a second current source I2;
one end of the fifth resistor R6 is connected to the first end of the first resistor R1, one end of the fourth resistor R5 is connected to the second end of the first resistor R1, the other end of the fifth resistor R6, the first switch tube Q1 and the first current source I1 are sequentially connected in series and then grounded, the other end of the fourth resistor R5, the second switch tube Q2 and the second current source I2 are sequentially connected in series and then grounded, and the other end of the fifth resistor R6 is also connected in series with the second series circuit through the isolating switch Q3 and then grounded;
the first end of the first resistor R1 is connected with the output end of a power supply; the fourth resistor R5 and the fifth resistor R6 have the same resistance value, the first current source I1 and the second current source I2 output the same current value, the current value on the second series circuit is equal to the difference value between the current on the fifth resistor R6 and the current on the fourth resistor R5, and the first switch tube Q1 and the second switch tube Q2 are triodes or MOS tubes.
Specifically, referring to fig. 4, taking the first switch tube Q1 and the second switch tube Q2 as PNP-type triodes as an example, the emitter of the first switch tube Q1 is connected to the other end of the fifth resistor R6, the collector is connected to the first current source I1, and the base and the collector are also connected to the end of the first current source I1 away from the ground end; the emitter of the second switch tube Q2 is connected with the other end of the fourth resistor R5, the collector is connected with the second current source I2, and the base is connected with the base of the first switch tube Q1.
The first switch tube Q1 and the second switch tube Q2 may also be MOS tubes.
The isolation switch Q3 may be a transistor, such as a PNP transistor, wherein an emitter of the transistor Q3 is connected to the other end of the fifth resistor R6, a collector of the transistor Q3 is connected to the second series circuit, and a base of the transistor Q3 is connected to the second current source I2 (specifically, connected to one end of the second current source I2 connected to the second switch Q2, that is, connected to a collector of the PNP transistor serving as the second switch Q2). The isolating switch Q3 is configured to isolate a voltage between the fifth resistor R6 and the second resistor R3 in the second series circuit, and voltages at two ends of the isolating switch Q3 may be unequal, so that a voltage at one end of the fifth resistor R6 connected to the isolating switch Q3 and a voltage at one end of the second resistor R3 connected to the isolating switch Q3 may be unequal.
In the embodiment of the present invention, when the first current source I1 and the second current source I2 are equal, veb of the first switch tube Q1 and the second switch tube Q2 are equal, and the base voltages of the first switch tube Q1 and the second switch tube Q2 are equal, so the emitter voltages Ve of the first switch tube Q1 and the second switch tube Q2 are equal, and the emitter currents flowing into the first switch tube Q1 and the second switch tube Q2 are also equal, at this time, it is assumed that the collector voltage of the first switch tube Q1 is Ve1, the collector current is Ie1, and the collector voltage of the second switch tube Q2 is equalVe2 and the collector current Ie2, ve1= Ve2 and Ie1= Ie2, and, assuming that the fourth resistor R5= the fifth resistor R6, the current flowing from the fifth resistor R6 to the second series circuit is I3, and therefore,
Figure 431377DEST_PATH_IMAGE005
(taking the example that the first resistor R1 is disposed between the power supply and the first series circuit, that is, one end of the first resistor R1 is connected to the power supply, the other end is connected to the first series circuit, the voltage at one end of the first resistor R1 connected to the power supply is Vin, and the voltage at the other end is V NSENSE ) Wherein Vin-V NSENSE The voltage value of (1) is the sampling voltage V on the first resistor R1 SENSE And therefore, the first and second electrodes are,
Figure 542552DEST_PATH_IMAGE006
，
Figure 490916DEST_PATH_IMAGE007
。
at this time, due to the existence of the second current source I2, the base of the PNP transistor serving as the isolation switch Q3 is always in a state of flowing current, and therefore, the isolation switch Q3 is always in a conducting state, when the current I3 is generated, the current I3 can flow to the second resistor R3 and the third resistor R4 through the isolation switch Q3, and the current is converted into the first voltage signal V1 to be input to the negative input end of the first comparing unit U4, and meanwhile, the positive input end voltage of the first comparing unit U4 is the second voltage signal VC obtained based on the adjusting signal, and therefore, finally, under the action of the first comparing unit U4, V1= VC is enabled.
In the embodiment of the present invention, a sampling amplifying circuit is formed by a first current source I1, a second current source I2, a second resistor R3, a third resistor R4, a fourth resistor R5, a fifth resistor R6, a first switch tube Q1, a second switch tube Q2, and an isolation switch Q3.
The sampling unit is not limited to the above circuit configuration, and other circuit configurations may be adopted as long as the voltage difference between the two ends of the first resistor R1 can be acquired.
About a sampling unitDuring the periods t0-t1 and t2-t3, when the PWM signal is high, the third controllable switch M3 is turned on at the same time, thereby short-circuiting the third resistor R4, so that at this time,
Figure 458872DEST_PATH_IMAGE008
and, therefore,
Figure 492688DEST_PATH_IMAGE009
(ii) a During the periods t1-t2 and t3-t4, when the PWM signal is low, the third controllable switch M3 is turned off at the same time, so that the third resistor R4 is connected to the sampling unit, and therefore,
Figure 141975DEST_PATH_IMAGE010
and therefore, the first and second electrodes are,
Figure 7163DEST_PATH_IMAGE011
. Since the second voltage signal VC is obtained based on the adjustment signal (specifically, the voltage signal input by the dimmer), and the voltage of VC is not changed under the same brightness of the LED lamp bead, after the hysteresis control module is set, the current control target on the first resistor R1 during t0-t1 and t2-t3 is greater than the current control target on the first resistor R1 during t1-t2 and t3-t 4. It can be known from the above analysis that through setting up the ratio of R6 and R3+ R4 and R6 and R3, can set up the average voltage drop of first resistance R1, restrict the electric current that flows through LED lamp pearl D1 and D2 promptly, the mode of current-limiting regulation is simple.
As a specific implementation, the first logic module further comprises a regulating unit; the adjusting signal is a linear adjusting signal or a pulse adjusting signal;
the adjusting unit is used for receiving the linear adjusting signal and outputting a corresponding second voltage signal according to the linear adjusting signal; or,
the regulating unit is used for receiving the pulse regulating signal and outputting a control signal for controlling the first series circuit to be connected or disconnected and a second voltage signal according to the pulse regulating signal; when the first series circuit is conducted, the second voltage signal output by the adjusting unit is a voltage signal with a first preset voltage value, and the first preset voltage value is a preset fixed voltage value;
the first logic module outputs the first control signal SWON and the second control signal SWON according to the second voltage signal and the sampling signal
Figure 83703DEST_PATH_IMAGE003
。
In the related art, common LED dimming methods include pulse dimming and linear dimming, wherein the pulse dimming can accurately control the current of an LED, so that the LED is suitable for occasions with constant color temperature, but the peripheral circuit is complex and has high cost, while the linear dimming method is simple and has low cost, but the LED is not suitable for occasions requiring constant color temperature; moreover, due to the difference of the control methods caused by the difference of the dimming modes, the control chip of the LED driving circuit is usually designed separately according to the dimming mode, that is, the control chip of a single LED driving circuit can only be applied to linear dimming or pulse dimming, thereby greatly limiting the application occasions of the LED driving circuit. In the embodiment of the invention, the adjusting unit enables the high-power driving circuit to have a linear dimming function and a pulse dimming function at the same time.
When the adjusting unit receives the linear adjusting signal, the size of the output second voltage signal is changed along with the change of the size of the linear adjusting signal.
Specifically, the control signal for controlling the on/off of the first series circuit may be used to control the state of the control module, the first logic module, or the control unit U5, where the state of the control module, the first logic module, or the control unit U5 includes a shutdown state and a working state. When the control module or the first logic module or the control unit U5 is in a normal working state, the first control signal SWON and the second control signal SWON can be normally output
Figure 604814DEST_PATH_IMAGE003
And thus the loop in which the first series circuit is located is conductive (including inductor L1 charging conduction and freewheeling conduction). When the control module or the first logic moduleWhen the block or control unit U5 is in the power-off state, the first control signal SWON and the second control signal SWON cannot be output
Figure 786354DEST_PATH_IMAGE003
So that the circuit in which the first series circuit is located is open.
As a further alternative specific implementation, please refer to fig. 4, the adjusting unit includes a sixth resistor R2, a second comparing unit U1, a third comparing unit U3, and a fourth controllable switch M4;
a first end of the sixth resistor R2 is configured to receive the adjustment signal, a second end of the sixth resistor R2 is connected to one input end of the second comparing unit U1 and one input end of the third comparing unit U3, the second end of the sixth resistor R2 is further grounded through the fourth controllable switch M4, another input end of the second comparing unit U1 is connected to the voltage signal with the first preset voltage value, an output end of the second comparing unit U1 is connected to a controlled end of the fourth controllable switch M4, and another input end of the third comparing unit U3 is connected to the voltage signal with the second preset voltage value; the first preset voltage value is greater than the second preset voltage value;
when the adjusting signal is a linear adjusting signal with a voltage value greater than the second preset voltage value and less than the first preset voltage value, the second comparing unit U1 outputs a control signal for controlling the fourth controllable switch M4 to be turned off, and the third comparing unit U3 outputs a control signal for controlling the first series circuit to be turned on; the voltage value of the second voltage signal output by the adjusting unit is equal to the voltage value at the second end of the sixth resistor R2 and equal to the voltage value of the adjusting signal input;
when the adjusting signal is a pulse adjusting signal and the pulse adjusting signal is in a low-voltage stage, the second comparing unit U1 outputs a control signal for controlling the fourth controllable switch M4 to be turned off, and the third comparing unit U3 outputs a control signal for controlling the first series circuit to be turned off; when the pulse adjusting signal is in a high-voltage stage, the second voltage signal output by the adjusting unit is the voltage signal of the first preset voltage value, and the third comparing unit U3 outputs a control signal for controlling the conduction of the first series circuit; the high voltage value of the pulse adjusting signal is greater than the first preset voltage value, and the low voltage value of the pulse adjusting signal is less than the second preset voltage value.
In this embodiment of the present invention, the fourth controllable switch M4 may be an N-channel MOS transistor, and the gate thereof is connected to the output terminal of the second comparing unit U1, the source thereof is grounded, and the drain thereof is connected to the second terminal of the sixth resistor R2. A second end of the sixth resistor R2 is connected to positive input ends of the second comparing unit U1 and the third comparing unit U3, respectively, a negative input end of the second comparing unit U1 is connected to the voltage signal of the first preset voltage BG, and a negative input end of the third comparing unit U3 is connected to the voltage signal of the second preset voltage V2.
When the adjusting signal is a linear adjusting signal with a voltage value greater than the second preset voltage value V2 and less than the first preset voltage value BG, that is, when the voltage of the adjusting signal is between the second preset voltage value V2 and the first preset voltage value BG, the second comparing unit U1 outputs a low level, the fourth controllable switch M4 is turned off, and the third comparing unit U3 outputs a high level, so that the control module or the first logic module or the control unit U5 is in a normal working state. The voltage value of the second voltage signal VC output by the adjusting unit is equal to the voltage value at the second end of the sixth resistor R2, the second voltage signal VC is used for comparing with the first voltage signal V1 output by the sampling unit, the comparison result is input to the control unit U5, and the first control signal SWON and the second control signal SWON are generated
Figure 771627DEST_PATH_IMAGE003
Thereby, the first controllable switch M1 and the second controllable switch M2 are controlled, and linear dimming is realized.
When the adjusting signal is a pulse adjusting signal (specifically, a pulse square wave with an adjustable duty ratio, a low voltage of the pulse adjusting signal is smaller than a second preset voltage value V2, and a high voltage of the pulse adjusting signal is larger than a first preset voltage value BG), and when the pulse adjusting signal is in a low-voltage stage, the second comparing unit U1 outputs a low level, the fourth controllable switch M4 is turned off, and meanwhile, the third comparing unit U3 outputs a low level, so that the control module or the first logic module or the control unit U5 is driven to be turned off. When the pulse adjusting signal is in a high-voltage stage, the second comparing unit U1 outputs a high level, the fourth controllable switch M4 is turned on, and the third comparing unit U3 outputs a high level to drive the control module or the first logic module or the control unit U5 to be in a normal working state.
In other specific embodiments, the second end of the sixth resistor R2 may be connected to a negative input end of the second comparing unit U1 and a negative input end of the third comparing unit U3, respectively, a positive input end of the second comparing unit U1 is connected to a voltage signal of the first preset voltage BG, a positive input end of the third comparing unit U3 is connected to a voltage signal of the second preset voltage V2, the control module or the first logic module or the control unit U5 is driven by a low level to be in a normal operating state, the control module or the first logic module or the control unit U5 is driven by a high level to be turned off, and the fourth controllable switch M4 is also driven by a low level to be turned on and driven by a high level to be turned off.
In a specific embodiment, referring to fig. 4, when the adjustment signal is the pulse adjustment signal and is in a high-voltage stage, the sixth resistor R2, the second comparing unit U1, and the fourth controllable switch M4 form a negative feedback circuit, when the negative feedback circuit reaches a steady state, a voltage of a positive input end of the second comparing unit U1 is equal to a voltage of a negative input end, and is equal to the first preset voltage value, and a voltage value of the second voltage signal output by the adjusting unit is equal to the voltage of the positive input end of the second comparing unit U1.
In the embodiment of the present invention, when the pulse adjustment signal is in a high-voltage stage, the second comparing unit U1 outputs a high level, the fourth controllable switch M4 is turned on, and at this time, the voltage BG of the first preset voltage value, the second comparing unit U1, the fourth controllable switch M4, and the sixth resistor R2 form a negative feedback circuit, that is, the high voltage of the pulse adjustment signal generates a current on the sixth resistor R2, the current flows to the ground through the fourth controllable switch M4, and then the voltage at the positive input end of the second comparing unit U1 decreases to be lower than the first preset voltage value BG, the second comparing unit U1 is turned off, the current path between the high voltage of the pulse adjustment signal and the ground is blocked, the high voltage of the pulse adjustment signal is all added to the positive input end of the second comparing unit U1, and the second comparing unit U1 outputs a high level to turn on the fourth controllable switch M4, so that, when the negative feedback circuit reaches a steady state, the voltage at the positive input end of the second comparing unit U1 is the voltage BG of the first preset voltage value.
In another specific embodiment, the adjusting unit further includes a voltage follower unit, an input end of the voltage follower unit is connected to the second end of the sixth resistor R2, and an output end of the voltage follower unit is used as an output end of the adjusting unit.
In the embodiment of the present invention, when the adjustment signal is a linear adjustment signal having a voltage value greater than the second preset voltage value V2 and less than the first preset voltage value BG, that is, when the voltage of the adjustment signal is between the second preset voltage value V2 and the first preset voltage value BG, the voltage output by the voltage following unit U2, that is, the second voltage signal VC, is positively correlated with the voltage of the adjustment signal.
When the adjustment signal is a pulse adjustment signal and the pulse adjustment signal is at a high-voltage stage, if the negative feedback circuit reaches a steady state, the voltage output by the voltage following unit, i.e., the second voltage signal VC, is equal to the voltage at the negative input end of the second comparing unit U1, i.e., the first preset voltage value BG. At this time, during the time period t0-t1 and t2-t3, when the PWM signal is high, the third controllable switch M3 is simultaneously turned on, thereby short-circuiting the third resistor R4, so that at this time,
Figure 19069DEST_PATH_IMAGE012
and, therefore,
Figure 27476DEST_PATH_IMAGE013
；
during the periods t1-t2 and t3-t4, when the PWM signal is low, the third controllable switch M3 is turned off at the same time, so that the third resistor R4 is connected to the sampling unit, and therefore,
Figure 80883DEST_PATH_IMAGE014
and therefore, the first and second electrodes are,
Figure 858346DEST_PATH_IMAGE015
；
thus, when the pulse adjust signal is high, the first logic block generates the SWON signal and
Figure 591203DEST_PATH_IMAGE003
and when the pulse adjusting signal is low voltage, the control module or the first logic module or the control unit U5 is turned off, so that the brightness of the LED lamp bead is adjusted by controlling the duty ratio of the pulse adjusting signal, namely pulse dimming is realized.
The embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments.
The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art to which the present application pertains. Any modification, equivalent replacement, improvement or the like made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims (9)

1. A driver circuit, comprising: the circuit comprises an inductor, a first controllable switch, a second controllable switch, a sampling circuit and a control module;
the inductor is connected with an element to be driven in series to form a first series circuit, a first end of the first series circuit is connected with a power supply, a second end of the first series circuit is connected with the first controllable switch in series and then grounded, and the second end of the first series circuit is also connected with the first end of the first series circuit through the second controllable switch;
the sampling circuit is respectively connected with the first series circuit and the control module and is used for collecting current information on the first series circuit and inputting a collected sampling signal to the control module;
the control module is also respectively connected with the controlled end of the first controllable switch and the controlled end of the second controllable switch, and is used for controlling the on-off of the first controllable switch and the second controllable switch according to the sampling signal, and when one of the first controllable switch and the second controllable switch is in an on state, the other one of the first controllable switch and the second controllable switch is in an off state;
the second controllable switch is an N-channel MOS (metal oxide semiconductor) transistor comprising a body diode, and the body diode is used for forming a closed freewheeling loop with the first series circuit when the first controllable switch and the second controllable switch are both in an open state;
further comprising: a voltage holding circuit;
the voltage holding circuit includes: a first capacitor;
the controlled end of the second controllable switch is connected with the first end of the second controllable switch through the first capacitor, and the controlled end of the second controllable switch is also connected with a first voltage; a first end of the second controllable switch is an end connected to a second end of the first series circuit;
the first voltage is greater than or equal to a preset threshold value, and the preset threshold value is a minimum voltage difference between a controlled end and a first end of the second controllable switch, which can enable the second controllable switch to be conducted;
the control module comprises a first logic module;
the first logic module is used for outputting a first control signal and a second control signal according to the sampling signal and the received regulating signal; the first control signal and the second control signal are respectively used for controlling the on-off of the first controllable switch and the on-off of the second controllable switch.
2. The drive circuit of claim 1, wherein the sampling circuit comprises a first resistor connected in series with the first series circuit;
the first logic module comprises a sampling unit, a first comparison unit and a control unit;
the sampling unit is used for acquiring a voltage difference between two ends of the first resistor to serve as the sampling signal and generating a first voltage signal based on the voltage difference;
the first comparing unit is configured to compare the first voltage signal with a second voltage signal to obtain a comparison result signal, where the second voltage signal is obtained based on the adjustment signal;
the control unit is used for outputting the first control signal and the second control signal based on the comparison result signal.
3. The driving circuit according to claim 2, wherein the sampling unit comprises a second resistor, a third resistor and a third controllable switch;
the second resistor and the third resistor are connected in series to form a second series circuit, and the input of the second series circuit is an electric signal obtained based on the voltage difference;
the third controllable switch is connected with the third resistor in parallel, and when the third controllable switch is switched on, the third resistor is short-circuited;
and the control unit outputs a control signal for controlling the third controllable switch to be switched on and off according to the first control signal and/or the second control signal output by the control unit.
4. The driving circuit of claim 3, wherein the sampling unit further comprises a fourth resistor, a fifth resistor, a first switch tube, a second switch tube, an isolation switch, a first current source and a second current source;
one end of the fifth resistor is connected with the first end of the first resistor, one end of the fourth resistor is connected with the second end of the first resistor, the other end of the fifth resistor, the first switch tube and the first current source are sequentially connected in series and then grounded, the other end of the fourth resistor, the second switch tube and the second current source are sequentially connected in series and then grounded, and the other end of the fifth resistor is also connected in series with the second series circuit through the isolating switch and then grounded;
the first end of the first resistor is connected with the output end of the power supply; the resistance values of the fourth resistor and the fifth resistor are equal, the current values output by the first current source and the second current source are equal, the current value on the second series circuit is equal to the difference value between the current on the fifth resistor and the current on the fourth resistor, and the first switch tube and the second switch tube are triodes or MOS tubes.
5. The driving circuit according to claim 4, wherein the first switching tube and the second switching tube are PNP type triodes, an emitter of the first switching tube is connected to the other end of the fifth resistor, a collector of the first switching tube is connected to the first current source, and a base and a collector of the first switching tube are connected to the first current source; and the emitting electrode of the second switch tube is connected with the other end of the fourth resistor, the collector electrode of the second switch tube is connected with the second current source, and the base electrode of the second switch tube is connected with the base electrode of the first switch tube.
6. The driving circuit of claim 1, wherein the first logic module further comprises an adjustment unit; the adjusting signal is a linear adjusting signal or a pulse adjusting signal;
the adjusting unit is used for receiving the linear adjusting signal and outputting a corresponding second voltage signal according to the linear adjusting signal; or,
the regulating unit is used for receiving the pulse regulating signal and outputting a control signal for controlling the first series circuit to be switched on or switched off and a second voltage signal according to the pulse regulating signal; when the first series circuit is conducted, the second voltage signal output by the adjusting unit is a voltage signal with a first preset voltage value, and the first preset voltage value is a preset fixed voltage value;
the first logic module outputs the first control signal and the second control signal according to the second voltage signal and the sampling signal.
7. The driving circuit according to claim 6, wherein the adjusting unit comprises a sixth resistor, a second comparing unit, a third comparing unit and a fourth controllable switch;
a first end of the sixth resistor is configured to receive the adjustment signal, a second end of the sixth resistor is connected to one input end of the second comparing unit and one input end of the third comparing unit, the second end of the sixth resistor is further grounded through the fourth controllable switch, another input end of the second comparing unit is connected to the voltage signal of the first preset voltage value, an output end of the second comparing unit is connected to a controlled end of the fourth controllable switch, and another input end of the third comparing unit is connected to the voltage signal of the second preset voltage value; the first preset voltage value is greater than the second preset voltage value;
when the adjusting signal is a linear adjusting signal with a voltage value larger than the second preset voltage value and smaller than the first preset voltage value, the second comparing unit outputs a control signal for controlling the fourth controllable switch to be switched off, and the third comparing unit outputs a control signal for controlling the first series circuit to be switched on; the voltage value of the second voltage signal output by the adjusting unit is equal to the voltage value at the second end of the sixth resistor and equal to the voltage value of the adjusting signal input by the adjusting unit;
when the adjusting signal is a pulse adjusting signal and the pulse adjusting signal is in a low-voltage stage, the second comparing unit outputs a control signal for controlling the fourth controllable switch to be switched off, and the third comparing unit outputs a control signal for controlling the first series circuit to be switched off; when the pulse adjusting signal is in a high-voltage stage, the second voltage signal output by the adjusting unit is a voltage signal of the first preset voltage value, and the third comparing unit outputs a control signal for controlling the conduction of the first series circuit; the high voltage value of the pulse adjusting signal is greater than the first preset voltage value, and the low voltage value of the pulse adjusting signal is less than the second preset voltage value.
8. The driving circuit according to claim 7, wherein when the adjustment signal is the pulse adjustment signal and is in a high-voltage stage, the sixth resistor, the second comparing unit, and the fourth controllable switch form a negative feedback circuit, when the negative feedback circuit reaches a steady state, a positive input terminal voltage and a negative input terminal voltage of the second comparing unit are equal to each other and equal to the first preset voltage value, and a voltage value of the second voltage signal output by the adjusting unit is equal to the positive input terminal voltage of the second comparing unit.
9. The driving circuit according to claim 8, wherein the adjusting unit further comprises a voltage follower unit, an input terminal of the voltage follower unit is connected to the second terminal of the sixth resistor, and an output terminal of the voltage follower unit is used as an output terminal of the adjusting unit.
CN202210516983.9A 2022-05-13 2022-05-13 High-power driving circuit Active CN114629353B (en)

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