CN210431988U - LED drive circuit and LED lighting device - Google Patents
LED drive circuit and LED lighting device Download PDFInfo
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- CN210431988U CN210431988U CN201921350012.1U CN201921350012U CN210431988U CN 210431988 U CN210431988 U CN 210431988U CN 201921350012 U CN201921350012 U CN 201921350012U CN 210431988 U CN210431988 U CN 210431988U
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Abstract
The utility model relates to an integrated circuit technical field, concretely relates to LED drive circuit, and adopted LED drive circuit's LED lighting apparatus. The LED drive circuit includes: the control circuit controls the first switch to be switched on based on the detection result of the control circuit on the current state of the energy storage inductor, the detection result on the voltage of the LED load and the detection result on the sampling signal of the sampling resistor on the basis of the detection result on the voltage sampling signal of the sampling resistor so as to charge the energy storage inductor or controls the first switch to be switched off, so that the energy storage inductor is discharged through the fly-wheel diode; the LED driving circuit integrates functions of overvoltage protection, demagnetization detection and power supply, so that the performance and the cost of the LED driving circuit are optimized.
Description
Technical Field
The utility model relates to an integrated circuit technical field, concretely relates to LED drive circuit, and adopted LED drive circuit's LED lighting apparatus.
Background
Fig. 1 shows a conventional LED driving circuit, in which a first terminal of an LED load is coupled to an input voltage VIN, a second terminal of the LED load is coupled to a first terminal of an energy storage inductor L1, a second terminal of the energy storage inductor L1 is coupled to a first terminal of a switch transistor M1 and is coupled to an anode of a freewheeling diode D1, a control terminal of the switch transistor M1 is coupled to the control circuit, a second terminal of the switch transistor is coupled to a first terminal of a current detection resistor Rcs, a second terminal of the current detection resistor Rcs is grounded, a cathode of the freewheeling diode D1 is coupled to the input voltage VIN, and the control circuit further has a HV terminal directly coupled to the input voltage, an over-voltage protection setting resistor ROVP coupled to the control circuit, and an output filter capacitor CO connected in parallel to the LED load.
The traditional LED driving circuit has two defects, firstly, the LED driving circuit utilizes the energy storage inductor demagnetization time to compare with the reference time in the chip to set the overvoltage protection of the LED driving circuit, and as the energy storage inductor demagnetization time is closely related to the precision of the energy storage inductor, the precision of an overvoltage protection point is not high, and the problem of overvoltage protection failure is easy to occur; secondly, the LED driving circuit detects the demagnetization end point of the energy storage inductor by using an oscillation signal generated by the end of the parasitic Cgd capacitive coupling energy storage inductor follow current of the switching tube M1, and is easily influenced by switching tubes of different types, and particularly when the energy storage inductor is an I-shaped inductor, the detection failure of the demagnetization end point of the energy storage inductor is easily caused, and the LED lighting equipment is caused to abnormally work.
SUMMERY OF THE UTILITY MODEL
The utility model provides a LED drive circuit to and adopted this LED drive circuit's LED lighting apparatus.
According to the utility model discloses a LED drive circuit of embodiment, include: the energy storage inductor is provided with a first end and a second end, wherein the first end is electrically coupled with the power supply input voltage, and the second end is electrically coupled with the first end of the LED load; an LED load having a first terminal and a second terminal, wherein the second terminal is electrically coupled to the first switch first terminal; the first switch is provided with a first end, a second end and a control end, wherein the control end is electrically coupled with the second end of the control circuit, and the second end is electrically coupled with the first end of the sampling resistor; a sampling resistor having a first terminal and a second terminal, wherein the second terminal is coupled to ground, the sampling resistor detects a current flowing through the first switch and outputs a voltage sampling signal; a freewheeling diode having a first terminal anode electrically coupled to the LED load and the first switch common and a second terminal cathode electrically coupled to the power supply input voltage and the first terminal of the energy storage inductor; the control circuit is provided with a first end, a second end and a third end, wherein the first end is electrically coupled with the common end of the energy storage inductor and the LED load, and the third end is electrically coupled with the common end of the first switch and the sampling resistor; the control circuit controls the first switch to be switched on to charge the energy storage inductor or controls the first switch to be switched off based on a detection result of the first end of the control circuit on the current state of the energy storage inductor and a detection result of the first end of the control circuit on the voltage of the LED load and a detection result of the third end of the control circuit on the voltage sampling signal, so that the energy storage inductor discharges through the fly-wheel diode.
According to the utility model discloses a LED drive circuit of embodiment, control circuit includes: the demagnetization detection module is provided with an input end and an output end, wherein the input end is electrically coupled with the energy storage inductor and the common end of the LED load, the output end is electrically coupled with the control driving module, and the demagnetization detection module outputs a zero current detection signal to be electrically coupled with the control driving module after detecting the current state of the energy storage inductor after the first switch is disconnected and after the current of the energy storage inductor is reduced to zero; the overvoltage detection module is provided with an input end and an output end, wherein the input end is electrically coupled with the energy storage inductor and the common end of the LED load, the output end is electrically coupled with the control driving module, the voltage of the first end of the LED load is detected after the first switch is conducted, and an overvoltage detection signal is output to be electrically coupled with the control driving module after the voltage exceeds a set value; the power supply module is provided with an input end and an output end, wherein the input end is electrically coupled with the energy storage inductor and the common end of the LED load, and provides stable power supply voltage and reference voltage for the control circuit by sampling the voltage of the first end of the LED load; the current detection control module is provided with a first input end, a second input end and an output end, wherein the first input end is electrically coupled with the first switch and the public end of the sampling resistor, the second input end is electrically coupled with a first reference voltage, the output end is electrically coupled with the control driving module, and a turn-off control signal is output and electrically coupled with the control driving module based on a processing result of a voltage sampling signal on the sampling resistor; the control drive module is respectively coupled with the demagnetization detection module, the overvoltage detection module and the current detection control module in an electric mode, receives the zero current detection signal, the overvoltage detection signal and the turn-off control signal, outputs a control signal, controls the first switch to be switched on so as to charge the energy storage inductor or controls the first switch to be switched off, so that the energy storage inductor is discharged through the fly-wheel diode.
According to the utility model discloses a LED drive circuit of embodiment, current detection control module, including peak value comparison module, peak value comparison module has first input, second input and output, wherein first input and second input respectively with voltage sampling signal and first reference voltage electricity on the sampling resistor are coupled, output turn-off control signal with control drive module electricity is coupled.
According to the utility model discloses a LED drive circuit of embodiment, current detection control module, include: the sampling operation module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with a voltage sampling signal on the sampling resistor and a control signal of the first switch control end, and output a sampling operation signal which is electrically coupled with the error amplification module; the error amplification module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with a first reference voltage and the sampling operation signal, and output an error amplification signal which is electrically coupled with the mean value comparison module; the slope generation module outputs a voltage slope signal and is electrically coupled with the mean value comparison module; and the average value comparison module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are electrically coupled with the error amplification signal and the voltage ramp signal respectively, and the output end outputs a turn-off control signal which is electrically coupled with the control driving module.
According to the utility model discloses a LED drive circuit of embodiment, excessive pressure detection module, include: the first voltage division circuit is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with a control signal of the first switch control end and a common end of the LED load and the energy storage inductor, and the output end outputs a first LED load voltage division signal related to the LED load voltage and is electrically coupled with the overvoltage comparison module; and the overvoltage comparison module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with the first LED load divided voltage signal and the second reference voltage signal, and the output end outputs an overvoltage protection signal to be electrically coupled with the control driving module.
According to the utility model discloses a LED drive circuit of embodiment, demagnetization detection module, include: the second voltage division circuit is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with an inverted logic signal of a control signal of the first switch control end and a common end of the LED load and the energy storage inductor, and the output end outputs a second LED load voltage division signal related to the voltage of the LED load to be electrically coupled with the demagnetization comparison module; the sampling and holding module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with the inverted logic signal of the control signal of the first switch control end and the second LED load voltage division signal, and the output end outputs a sampling and holding signal related to the second LED load voltage division signal and is electrically coupled with the demagnetization comparison module; demagnetization comparison module has first input, second input and output, wherein first input and second input respectively with second LED load partial pressure signal with the sample keeps signal electricity coupling, and the output exports a demagnetization detected signal and control driver module electricity coupling.
According to the utility model discloses a LED drive circuit of embodiment, the sample hold module, include: the single-pulse circuit is provided with an input end and an output end, wherein the input end is an inverted logic signal of the control end of the first switch, and the output end outputs a single-pulse signal related to the inverted logic signal and used for controlling the sampling switch to sample and hold the second LED load voltage division signal when the inverted logic signal is changed into high level; the sampling switch is provided with an input end, an output end and a control end, wherein the input end is electrically coupled with the second LED load voltage division signal, the control end is electrically coupled with the single pulse signal, and the output end is electrically coupled with the first end of the sampling capacitor; and the sampling capacitor is provided with a first end and a second end, wherein the second end is electrically coupled with the ground, and the first end of the sampling capacitor is electrically coupled with the demagnetization comparator.
According to an embodiment of the present invention, the first switch is an NMOS transistor, a gate of the NMOS transistor is electrically coupled to the second end of the control circuit, a source of the NMOS transistor is electrically coupled to the first end of the sampling resistor, and a drain of the NMOS transistor is electrically coupled to the second end of the LED load; or the first switch is a triode, the base electrode of the triode is electrically coupled with the second end of the control circuit, the emitting electrode of the triode is electrically coupled with the first end of the sampling resistor, and the collecting electrode of the triode is electrically coupled with the second end of the LED load.
According to the utility model discloses a LED drive circuit of an embodiment still includes: and the filter ripple capacitor is connected with the LED load in parallel and is suitable for filtering the current ripple of the load.
According to the utility model discloses a LED lighting apparatus of embodiment, including LED drive circuit.
The utility model provides a LED drive circuit framework has utilized resistance partial pressure to monitor actual LED load voltage to and utilized resistance partial pressure to monitor the oscillating signal after the energy storage inductance demagnetization finishes, can solve overvoltage protection precision problem and demagnetization detection unreliable problem that relate among the traditional LED drive circuit well, practiced thrift the cost, promoted the performance and the reliability of system.
Drawings
FIG. 1 is a schematic diagram of a conventional LED driving circuit;
fig. 2 is a schematic diagram of an LED driving circuit according to an embodiment of the present invention;
fig. 3A is a schematic diagram of a current detection control module according to an embodiment of the present invention;
fig. 3B is a schematic diagram of a current detection control module according to another embodiment of the present invention;
fig. 3C is a schematic diagram of an overvoltage detection module according to an embodiment of the present invention;
fig. 3D is a schematic diagram of a demagnetization detection module according to an embodiment of the present invention;
fig. 3E is a schematic diagram of a sample and hold module according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a typical operating waveform according to an embodiment of the present invention;
Detailed Description
Specific embodiments of the present invention will be described in detail below, and it should be noted that the embodiments described herein are only for illustration and are not intended to limit the present invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: it is not necessary to employ these specific details to practice the invention. In other instances, well-known circuits, materials, or methods have not been described in detail in order to avoid obscuring the present invention.
Throughout the specification, reference to "one embodiment," "an embodiment," "one example," or "an example" means: the particular features, structures, or characteristics described in connection with the embodiment or example are included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example" or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present. Like reference numerals refer to like elements. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Fig. 2 is a schematic diagram 200 of an LED driving circuit according to an embodiment of the present invention, which includes: an energy storage inductor 202 having a first terminal electrically coupled to the power input voltage VIN and a second terminal electrically coupled to a first terminal (forward terminal) of the LED load 203; the LED load 203 has a first terminal and a second terminal, wherein the second terminal (negative terminal) is electrically coupled to the first terminal of the first switch 206; a first switch 206 having a first terminal, a second terminal and a control terminal, wherein the control terminal is electrically coupled to the second terminal of the control circuit 201, and the second terminal is electrically coupled to the first terminal of the sampling resistor 207; a sampling resistor 207 having a first terminal and a second terminal, wherein the second terminal is coupled to ground, the sampling resistor 207 detecting a current flowing through the first switch 206 and outputting a voltage sampling signal VCS; a freewheeling diode 205 having a first terminal anode electrically coupled to the common terminal of the LED load 203 and the first switch 206 and a second terminal cathode electrically coupled to the power supply input voltage VIN and the first terminal of the energy storage inductor 202; a control circuit 201 having a first terminal electrically coupled to the common terminal of the energy storage inductor 202 and the LED load 203, a second terminal electrically coupled to the common terminal of the first switch 206 and the sampling resistor 207, and a third terminal; the control circuit 201 controls the first switch 206 to be turned on to charge the energy storage inductor 202 or controls the first switch 206 to be turned off based on the detection result of the first terminal of the control circuit on the current state of the energy storage inductor 202 and the detection result on the voltage of the LED load 203 and the detection result of the third terminal of the control circuit on the voltage sampling signal VCS, so that the energy storage inductor 202 is discharged through the freewheeling diode 205.
In an embodiment of the present invention, as shown in fig. 2, the control circuit 201 includes: the demagnetization detection module 210 is provided with an input end and an output end, wherein the input end LEDP is electrically coupled with a common end of the energy storage inductor 202 and the LED load 203, the output end is electrically coupled with the control driving module 240, and after the first switch 206 is detected to be switched off, the current state of the energy storage inductor 202 outputs a zero current detection signal ZXC to be electrically coupled with the control driving module 240 after the current of the energy storage inductor 202 is reduced to zero; the overvoltage detection module 220 is provided with an input end and an output end, wherein the input end LEDP is electrically coupled to the common end of the energy storage inductor 202 and the LED load 203, the output end is electrically coupled to the control driving module 240, and after the first switch 206 is turned on, the voltage LEDP at the first end of the LED load 203 is detected, and after the voltage exceeds a set value, an overvoltage detection signal OVP is output and electrically coupled to the control driving module 240; a power supply module 230 having an input end and an output end, wherein the input end LEDP is electrically coupled to the common end of the energy storage inductor 202 and the LED load 203, and the voltage of the first end LEDP of the LED load 203 is sampled to provide a stable supply voltage and a reference voltage to the control circuit 201, wherein the reference voltage is VREF1 in one embodiment, and the supply voltage is VDD; a current detection control module 250 having a first input terminal electrically coupled to the common terminal of the first switch 206 and the sampling resistor 207, a second input terminal electrically coupled to the first reference voltage VREF1, and an output terminal electrically coupled to the control driver module 240, and outputting a turn-OFF control signal OFF to be electrically coupled to the control driver module 240 based on a processing result of the voltage sampling signal VCS on the sampling resistor 207; control drive module 240, respectively with demagnetization detection module 210, excessive pressure detection module 220 and current detection control module 250 electricity coupling, receive zero current detection signal ZXC, excessive pressure detection signal OVP and turn OFF control signal OFF, output a control signal PWM, control first switch 206 switches on, and is right energy storage inductance 202 charges, or control first switch 206 breaks OFF, makes energy storage inductance 202 passes through freewheel diode 205 discharges.
In an embodiment of the present invention, as shown in fig. 3A, the current detection control module 250 includes a peak value comparison module 251, the peak value comparison module 251 has a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are electrically coupled to the voltage sampling signal VCS on the sampling resistor 207 and the first reference voltage VREF1, and the output terminal outputs the turn-OFF control signal OFF and the control driving module 240 is electrically coupled. In one embodiment, the OFF control signal OFF triggers the control signal of the first switch 206 to go low, turning OFF a switch 206.
In one embodiment, the first reference voltage VREF1 sets a peak value of the voltage sampling signal VCS, after the first switch 206 is turned on, the input voltage VIN charges the energy storage inductor 202 through the LED load 203, the first switch 206 and the sampling resistor 207, the constant charging voltage causes a current flowing through the energy storage inductor 202 to increase linearly, the charging current of the energy storage inductor 202 flows through the sampling resistor 207, the obtained voltage sampling signal VCS also increases linearly, and when the peak value of the voltage sampling signal VCS reaches and exceeds the first reference voltage VREF1, the peak value comparing module 251 compares the OFF control signal OFF to the control driving module 240, triggers the control signal PWM output by the control driving module 240 to become a low level, and turns OFF the first switch 206, thereby implementing peak value control on the voltage sampling signal VCS.
In another embodiment of the present invention, as shown in fig. 3B, the current detection control module 250 includes: a sampling operation module 252 having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are electrically coupled to the voltage sampling signal VCS on the sampling resistor 207 and the control signal PWM of the control terminal of the first switch 206, respectively, and output a sampling operation signal VCS _ avg electrically coupled to the error amplification module 253; in one embodiment, the sampling operation signal Vcs _ avg represents an average value of the voltage sampling signal Vcs in one period, such as Vcs _ avg ═ Vcs × PWM + Vcs _ pk × PWMB 0.5, where Vcs _ pk represents a peak voltage of the voltage sampling signal Vcs and PWMB represents a logical inverse signal of the PWM signal; an error amplifying module 253 having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are electrically coupled to the first reference voltage VREF1 and the sampling operation signal VCS _ avg, respectively, and output an error amplifying signal VERR electrically coupled to the mean value comparing module 255; in one embodiment, the error amplification module comprises a compensation capacitor for maintaining the error amplification module in a steady state operation; a ramp generating module 254 for outputting a voltage ramp signal VRAMP electrically coupled to the mean comparing module 255; and an average comparing module 255 having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are electrically coupled to the error amplifying signal VERR and the voltage ramp signal VRAMP, respectively, and the output terminal outputs a turn-OFF control signal OFF to be electrically coupled to the control driving module 240. In one embodiment, the OFF control signal OFF triggers the control signal of the first switch 206 to go low, turning OFF a switch 206.
In one embodiment, the first reference voltage VREF1 sets an average value of the voltage sampling signal VCS, after the first switch 206 is turned on, the input voltage VIN charges the energy storage inductor 202 through the LED load 203, the first switch 206 and the sampling resistor 207, the constant charging voltage makes the current flowing through the energy storage inductor 202 increase linearly, the charging current of the energy storage inductor 202 flows through the sampling resistor 207, the obtained voltage sampling signal VCS also increases linearly, the sampling operation module 252 inputs the average value of the voltage sampling signal VCS in each switching period and the first reference voltage VREF1 together into the error amplification module 253 for error amplification, and generates an error amplification signal VERR, which is compared with the voltage ramp VRAMP generated by the ramp generation module 254 in the average comparison module 255, and then outputs the OFF control signal OFF to the control driving module 240, the average value control of the voltage sampling signal VCS is realized.
In an embodiment of the present invention, as shown in fig. 3C, the overvoltage detection module 220 includes: a first voltage dividing circuit 221 having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are respectively electrically coupled to the control signal PWM at the control terminal of the first switch 206, and the LED load 203 is electrically coupled to the common terminal of the energy storage inductor 202, and the output terminal outputs a first LED load voltage dividing signal VN1 related to the voltage of the LED load 203 and is electrically coupled to the overvoltage comparing module 222; the overvoltage comparing module 222 has a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are electrically coupled to the first LED load dividing signal VN1 and the second reference voltage signal VREF2, respectively, and the output terminal outputs an overvoltage protection signal OVP electrically coupled to the control driving module 240, and the overvoltage protection signal OVP triggers the control signal of the first switch 206 to become low level, so as to open a switch 206.
In one embodiment, as can be seen from the LED driving circuit diagram 200 of fig. 2 and the exemplary operating waveform diagram of fig. 4, the voltage VLED of the LED load 203 is superimposed on the first terminal VSW of the first switch 206, so that the first terminal voltage LEDP of the LED load 203 is VSW + VLED, during the conduction period of the first switch 206, the input voltage VIN charges the energy storage inductor 202 through the LED load 203, the first switch 206 and the sampling resistor 207, the constant charging voltage linearly increases the current flowing through the energy storage inductor 202, neglecting the conduction voltage drop of the first switch, the low level of the first terminal voltage VSW of the first switch 206 is approximately equal to the voltage sampling signal VCS, and the low level of VSW is approximately equal to zero relative to the high level of VSW, so that during the conduction period of the first switch 206, the voltage LEDP is VLED + VCS, and after neglecting the VCS voltage is VLED; therefore, during the period when the first switch 206 is turned on, the voltage VN1 ═ K1 ═ VLED (where K1 is a voltage division coefficient and is a constant) of the LED load 203 can be accurately sampled by the first voltage dividing resistor 221, and by comparing VN1 with the second reference voltage VREF2, the overvoltage protection point VREF2 ═ K1 ═ VLED, and the VLED ═ VREF2/K1 of the LED load 203 can be accurately determined.
In an embodiment of the present invention, as shown in fig. 3D, the demagnetization detecting module 210 includes: the second voltage dividing circuit 211 has a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are respectively electrically coupled to the inverted logic signal PWMB of the control signal PWM at the control terminal of the first switch 206, and the common terminal of the energy storage inductor 202 and the output terminal outputs a second LED load voltage dividing signal VN2 related to the voltage of the LED load 203 and is electrically coupled to the demagnetization comparing module 213; a sample-and-hold module 212 having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are electrically coupled to the inverse logic signal PWMB of the control signal PWM at the control terminal of the first switch 206 and the second LED load dividing signal VN2 respectively, and the output terminal outputs a sample-and-hold signal VSMP related to the second LED load dividing signal VN2 and is electrically coupled to the demagnetization comparison module 213; and the demagnetization comparison module 213 is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with the second LED load voltage division signal VN2 and the sample hold signal VSMP, and the output end outputs a demagnetization detection signal ZXC which is electrically coupled with the control driving module 240. In one embodiment, the second voltage divider 211 may demultiplex the same voltage divider resistors with the first voltage divider 221 through different operation states of the control signals PWM and PWMB.
In an embodiment of the present invention, as shown in fig. 3E, the sample-and-hold module includes: a single pulse circuit 212a having an input terminal which is an inverted logic signal PWMB of the control signal PWM at the control terminal of the first switch 206 and an output terminal which outputs a single pulse signal related to the inverted logic signal PWMB for controlling the sampling switch 212b to sample and hold the second LED load dividing voltage signal VN2 when the inverted logic signal PWMB goes high; a sampling switch 212b having an input terminal electrically coupled to the second LED load dividing signal VN2, an output terminal electrically coupled to the single pulse signal, and a control terminal electrically coupled to the first terminal of the sampling capacitor 212 c; and the sampling capacitor 212c is provided with a first end and a second end, wherein the second end is electrically coupled with the ground, and the first end of the sampling capacitor 212c is also electrically coupled with the demagnetization comparator 213.
In one embodiment, it can be seen from the LED driving circuit diagram 200 of fig. 2 and the exemplary operating waveform diagram of fig. 4 that, during the period when the first switch 206 is turned off, the energy storage inductor 202 discharges the LED load 203 through the freewheeling diode 205, the current of the energy storage inductor 202 decreases linearly, ignoring the conduction voltage drop of the freewheeling diode 205, the VSW voltage during this period is approximately equal to the input voltage VIN, and the first end voltage LEDP of the LED load 203 is approximately equal to VLED + VIN; after the current of the energy storage inductor 202 drops to zero, because there is a parasitic capacitance at the second end of the energy storage inductor 202, there is LC oscillation at the second end voltage of the energy storage inductor 202, that is, the LED load 203 first end voltage LEDP, so that the second voltage dividing circuit 211 can detect the oscillation state of the LEDP voltage through resistive voltage division during the off period of the first switch 206, so as to obtain the second LED load voltage dividing signal VN 2; after the control signal PWMB becomes high level, a single pulse with high level is generated under the action of the single pulse circuit 212a to turn on the sampling switch 212b, so as to realize voltage sampling on the second LED load voltage division signal VN2, and after the high level of the single pulse is finished, the sampling capacitor 212c holds the second LED load voltage division signal VN2 obtained by sampling, and the holding level is VSMP; after the current of the energy storage inductor 202 drops to zero, the voltage LEDP at the first end of the LED load 203 will have LC oscillation, and at the same time, the second LED load voltage division signal VN2 also has the same oscillation, when the oscillation causes the voltage of VN2 to be lower than the voltage VSMP held by the sampling capacitor 212c, the demagnetization comparison module 213 compares the output ZXC signal to become a high level, which indicates that the demagnetization of the energy storage inductor 202 has ended. In one embodiment, the ZXC signal going high also triggers the control signal PWM of the first switch 206 to go high, turning on the first switch 206 and entering the next cycle.
In an embodiment of the present invention, as shown in fig. 2, the first switch 206 is an NMOS transistor, a gate of the NMOS transistor is electrically coupled to the second end of the control circuit 201, a source of the NMOS transistor is electrically coupled to the first end of the sampling resistor 207, and a drain of the NMOS transistor is electrically coupled to the second end of the LED load 203; or the first switch 206 is a triode, the base of which is electrically coupled to the second end of the control circuit 201, the emitter of which is electrically coupled to the first end of the sampling resistor 207, and the collector of which is electrically coupled to the second end of the LED load 203.
In an embodiment of the present invention, as shown in fig. 2, the LED driving circuit 200 further includes a ripple filtering capacitor 204 connected in parallel with the LED load 203 and adapted to filter the current ripple of the load.
According to the utility model discloses a LED lighting apparatus of embodiment, including LED drive circuit.
While the present invention has been described with reference to several exemplary embodiments, it is understood that the terminology used is intended to be in the nature of words of description and illustration, rather than of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims. For those skilled in the art, without departing from the principle of the present invention, several improvements and decorations can be made, and these improvements and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. An LED driving circuit, comprising:
the energy storage inductor is provided with a first end and a second end, wherein the first end is electrically coupled with the power supply input voltage, and the second end is electrically coupled with the first end of the LED load;
an LED load having a first terminal and a second terminal, wherein the second terminal is electrically coupled to the first switch first terminal;
the first switch is provided with a first end, a second end and a control end, wherein the control end is electrically coupled with the second end of the control circuit, and the second end is electrically coupled with the first end of the sampling resistor;
a sampling resistor having a first terminal and a second terminal, wherein the second terminal is coupled to ground, the sampling resistor detects a current flowing through the first switch and outputs a voltage sampling signal;
a freewheeling diode having a first terminal anode electrically coupled to the LED load and the first switch common and a second terminal cathode electrically coupled to the power supply input voltage and the first terminal of the energy storage inductor;
the control circuit is provided with a first end, a second end and a third end, wherein the first end is electrically coupled with the common end of the energy storage inductor and the LED load, and the third end is electrically coupled with the common end of the first switch and the sampling resistor; the control circuit controls the first switch to be switched on to charge the energy storage inductor or controls the first switch to be switched off based on a detection result of the first end of the control circuit on the current state of the energy storage inductor and a detection result of the first end of the control circuit on the voltage of the LED load and a detection result of the third end of the control circuit on the voltage sampling signal, so that the energy storage inductor discharges through the fly-wheel diode.
2. The LED driving circuit according to claim 1, wherein the control circuit comprises:
the demagnetization detection module is provided with an input end and an output end, wherein the input end is electrically coupled with the energy storage inductor and the common end of the LED load, the output end is electrically coupled with the control driving module, and the demagnetization detection module outputs a zero current detection signal to be electrically coupled with the control driving module after detecting the current state of the energy storage inductor after the first switch is disconnected and after the current of the energy storage inductor is reduced to zero;
the overvoltage detection module is provided with an input end and an output end, wherein the input end is electrically coupled with the energy storage inductor and the common end of the LED load, the output end is electrically coupled with the control driving module, the voltage of the first end of the LED load is detected after the first switch is conducted, and an overvoltage detection signal is output to be electrically coupled with the control driving module after the voltage exceeds a set value;
the power supply module is provided with an input end and an output end, wherein the input end is electrically coupled with the energy storage inductor and the common end of the LED load, and provides stable power supply voltage and reference voltage for the control circuit by sampling the voltage of the first end of the LED load;
the current detection control module is provided with a first input end, a second input end and an output end, wherein the first input end is electrically coupled with the first switch and the public end of the sampling resistor, the second input end is electrically coupled with a first reference voltage, the output end is electrically coupled with the control driving module, and a turn-off control signal is output and electrically coupled with the control driving module based on a processing result of a voltage sampling signal on the sampling resistor;
the control drive module is respectively coupled with the demagnetization detection module, the overvoltage detection module and the current detection control module in an electric mode, receives the zero current detection signal, the overvoltage detection signal and the turn-off control signal, outputs a control signal, controls the first switch to be switched on so as to charge the energy storage inductor or controls the first switch to be switched off, so that the energy storage inductor is discharged through the fly-wheel diode.
3. The LED driving circuit of claim 2, wherein the current detection control module comprises a peak comparison module having a first input terminal, a second input terminal and an output terminal, wherein the first input terminal and the second input terminal are electrically coupled to the voltage sampling signal and the first reference voltage respectively, and the output terminal outputs a turn-off control signal electrically coupled to the control driving module.
4. The LED driving circuit according to claim 2, wherein the current detection control module comprises:
the sampling operation module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with a voltage sampling signal on the sampling resistor and a control signal of the first switch control end, and output a sampling operation signal which is electrically coupled with the error amplification module;
the error amplification module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with a first reference voltage and the sampling operation signal, and output an error amplification signal which is electrically coupled with the mean value comparison module;
the slope generation module outputs a voltage slope signal and is electrically coupled with the mean value comparison module;
and the average value comparison module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are electrically coupled with the error amplification signal and the voltage ramp signal respectively, and the output end outputs a turn-off control signal which is electrically coupled with the control driving module.
5. The LED driver circuit of claim 2, wherein the over-voltage detection module comprises:
the first voltage division circuit is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with a control signal of the first switch control end and a common end of the LED load and the energy storage inductor, and the output end outputs a first LED load voltage division signal related to the LED load voltage and is electrically coupled with the overvoltage comparison module;
and the overvoltage comparison module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with the first LED load divided voltage signal and the second reference voltage signal, and the output end outputs an overvoltage protection signal to be electrically coupled with the control driving module.
6. The LED driving circuit according to claim 2, wherein the demagnetization detecting module includes:
the second voltage division circuit is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with an inverted logic signal of a control signal of the first switch control end and a common end of the LED load and the energy storage inductor, and the output end outputs a second LED load voltage division signal related to the voltage of the LED load to be electrically coupled with the demagnetization comparison module;
the sampling and holding module is provided with a first input end, a second input end and an output end, wherein the first input end and the second input end are respectively electrically coupled with the inverted logic signal of the control signal of the first switch control end and the second LED load voltage division signal, and the output end outputs a sampling and holding signal related to the second LED load voltage division signal and is electrically coupled with the demagnetization comparison module;
demagnetization comparison module has first input, second input and output, wherein first input and second input respectively with second LED load partial pressure signal with the sample keeps signal electricity coupling, and the output exports a demagnetization detected signal and control driver module electricity coupling.
7. The LED driver circuit of claim 6, wherein the sample-and-hold module comprises:
the single-pulse circuit is provided with an input end and an output end, wherein the input end is an inverted logic signal of the control end of the first switch, and the output end outputs a single-pulse signal related to the inverted logic signal and used for controlling the sampling switch to sample and hold the second LED load voltage division signal when the inverted logic signal is changed into high level;
the sampling switch is provided with an input end, an output end and a control end, wherein the input end is electrically coupled with the second LED load voltage division signal, the control end is electrically coupled with the single pulse signal, and the output end is electrically coupled with the first end of the sampling capacitor;
and the sampling capacitor is provided with a first end and a second end, wherein the second end is electrically coupled with the ground, and the first end of the sampling capacitor is electrically coupled with the demagnetization comparator.
8. The LED driving circuit according to claim 1, wherein the first switch is an NMOS transistor, a gate of the NMOS transistor is electrically coupled to the second terminal of the control circuit, a source of the NMOS transistor is electrically coupled to the first terminal of the sampling resistor, and a drain of the NMOS transistor is electrically coupled to the second terminal of the LED load; or the first switch is a triode, the base electrode of the triode is electrically coupled with the second end of the control circuit, the emitting electrode of the triode is electrically coupled with the first end of the sampling resistor, and the collecting electrode of the triode is electrically coupled with the second end of the LED load.
9. The LED driving circuit according to claim 1, further comprising:
and the filter ripple capacitor is connected with the LED load in parallel and is suitable for filtering the current ripple of the load.
10. An LED lighting device characterized by comprising the LED driving circuit according to any one of claims 1 to 9.
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| CN201921350012.1U CN210431988U (en) | 2019-08-19 | 2019-08-19 | LED drive circuit and LED lighting device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110461064A (en) * | 2019-08-19 | 2019-11-15 | 芯好半导体(成都)有限公司 | A kind of LED drive circuit, LED driving method and LED illumination device |
| CN110515414A (en) * | 2019-09-20 | 2019-11-29 | 芯好半导体(成都)有限公司 | A kind of constant-current control circuit, method and constant-current control device |
-
2019
- 2019-08-19 CN CN201921350012.1U patent/CN210431988U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110461064A (en) * | 2019-08-19 | 2019-11-15 | 芯好半导体(成都)有限公司 | A kind of LED drive circuit, LED driving method and LED illumination device |
| CN110515414A (en) * | 2019-09-20 | 2019-11-29 | 芯好半导体(成都)有限公司 | A kind of constant-current control circuit, method and constant-current control device |
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Effective date of registration: 20210823 Address after: 200120 5th floor, building 2, Lane 666, zhangheng Road, Pudong New Area, Shanghai Patentee after: Shanghai Bright Power Semiconductor Co.,Ltd. Address before: No.2126 and 2127, 21 / F, building 1, No.56, Tianhui middle street, hi tech Zone, Chengdu, Sichuan Province 610000 Patentee before: Xinhao semiconductor (Chengdu) Co.,Ltd. |