CN110798938A - LED driver - Google Patents
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- CN110798938A CN110798938A CN201911083031.7A CN201911083031A CN110798938A CN 110798938 A CN110798938 A CN 110798938A CN 201911083031 A CN201911083031 A CN 201911083031A CN 110798938 A CN110798938 A CN 110798938A
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Abstract
The invention discloses an LED driver, comprising: the PFC circuit comprises a PFC main circuit, a driving control circuit, an isolation circuit, a voltage regulating circuit, a frequency control driving circuit, a current regulating circuit and a resonant DC-DC circuit, wherein the PFC main circuit is connected with the resonant DC-DC circuit, the resonant DC-DC circuit is respectively connected with the input end of the current regulating circuit and the input end of the voltage regulating circuit, the output end of the current regulating circuit is connected with the input end of the frequency control driving circuit, the output end of the frequency control driving circuit is connected with the resonant DC-DC circuit, the output end of the voltage regulating circuit is connected with the input end of the driving control circuit through the isolation circuit, and the output end of the driving control circuit is connected with the PFC main circuit. According to the LED driver, the LED driver realizes multi-path output of the LED driver through different coupling coefficients of the two secondary windings and the primary winding of the transformer, and realizes constant voltage output and constant current output in the multi-path output of one LED through the voltage regulating circuit and the current regulating circuit.
Description
Technical Field
The invention relates to the technical field of lighting equipment, in particular to an LED driver.
Background
The LED has the advantages of energy conservation, environmental protection, long service life, high conversion efficiency and the like, and is widely applied to the field of illumination. The LED driver converts an input voltage into a direct current and supplies the direct current to an LED load. Currently, there are two types of LED drivers, one is an LED driver outputting a constant current, and the other is an LED driver outputting a constant voltage. In some lighting occasions, the same driver is required to drive two paths of loads simultaneously, the existing LED driver can output two or more paths of outputs, but the multiple paths of outputs of the same driver are of the same type, namely, the same driver has multiple paths of constant current outputs or multiple paths of constant voltage outputs, but the constant current outputs and the constant voltage outputs in the multiple paths of outputs of the same driver cannot be realized.
For example, a "constant voltage and constant current driver for high power LED spot light" disclosed in chinese patent document, whose publication No. CN201467519U, published 2010, 05 and 12 months, includes a power input terminal, a rectifying circuit connected to the power input terminal, a switching transformer connected to the rectifying circuit, and an output terminal connected to the switching transformer for connecting to a load LED, and is characterized in that: the power driving constant voltage circuit comprises a power driving circuit and a constant voltage control circuit, the power driving circuit is arranged between the PFC circuit and the switch transformer, the constant voltage control circuit collects output signals of the switch transformer and generates feedback signals to the power driving circuit, and the constant current circuit is arranged between the switch transformer and an output end. The constant-voltage constant-current output of the LED driver is realized through the constant-current circuit and the constant-voltage current, but the LED driver can only realize the constant-voltage or constant-current output, and cannot realize the constant-current output and the constant-voltage output in the multi-path output of the same driver.
Disclosure of Invention
The invention mainly solves the problem that the LED driver in the prior art can not realize that the same driver can output constant voltage and constant current at the same time; the LED driver has constant current output and constant voltage output in multi-path output of the same driver through constant voltage and constant current detection regulation.
The technical problem of the invention is mainly solved by the following technical scheme: an LED driver comprises a PFC main circuit, a drive control circuit, an isolation circuit, a voltage regulation circuit, a frequency control drive circuit, a current regulation circuit and a resonant DC-DC circuit, wherein the input end of the PFC main circuit is used as the input end of the LED driver and is used for being connected with a power supply, the output end of the PFC main circuit is connected with the input end of the resonant DC-DC circuit, the output end of the resonant DC-DC circuit comprises a constant voltage output end and a constant current output end, the input end of the current regulation circuit is connected with the constant current output end, the output end of the current regulation circuit is connected with the frequency control drive circuit, the current regulation circuit is used for detecting the current output by the constant current output end and outputting a first feedback signal to the frequency control drive circuit, and the frequency control drive circuit outputs a first drive signal to the resonant DC-DC circuit according to the magnitude of the first feedback signal, the working frequency of the resonant DC-DC circuit is used for maintaining the constant current output by the constant current output end, the input end of the voltage regulating circuit is connected with the constant voltage output end, the output end of the voltage regulating circuit is connected with the drive control circuit through an isolation circuit, the voltage regulating circuit is used for detecting the voltage output by the constant voltage output end and outputting a second feedback signal to the drive control circuit through the isolation circuit, and the drive control circuit outputs a second drive signal to the PFC main circuit according to the magnitude of the second feedback signal to enable the output voltage of the PFC main circuit to be constant, so that the voltage of the constant voltage output end is constant. The constant-voltage output is realized by connecting a power supply to an input end of a PFC main circuit, boosting the voltage by the PFC circuit and outputting the boosted voltage to a resonant DC-DC circuit, constant-voltage and constant-current output is performed by the resonant DC-DC circuit, constant-voltage detection is performed on the voltage output by the resonant DC-DC circuit by a voltage regulating circuit, the detection result is fed back to a driving control circuit, the output voltage of the PFC main circuit is regulated by the driving control circuit, constant-voltage output is realized, constant-current detection is performed on the current output by the resonant DC-DC circuit by a current regulating circuit, the detection result is fed back to a frequency control driving circuit, the output current of the resonant DC-DC circuit is regulated by the frequency control driving circuit, constant-current output is realized, and both constant-voltage output and constant-current.
Preferably, the PFC main circuit includes an inductor L, a switching tube S0, a diode D1, and a capacitor C0, one end of the inductor L is connected to a positive electrode of a power supply, the other end of the inductor L is connected to one end of the switching tube S0 and an anode of the diode D1, the other end of the switching tube S0 is connected to one end of the capacitor C0 and a negative electrode of the power supply, the other end of the capacitor C0 is connected to a cathode of the diode D1, and two ends of the capacitor C0 are further connected to the resonant DC-DC circuit as an output end of the PFC main circuit. The current passes through the inductor L, prevents that high voltage interference signal from damaging the circuit, controls the voltage of storing in the both ends of electric capacity C0 through switch tube S0, realizes carrying out control regulation to the output voltage Vbus of PFC main circuit, and diode D1 prevents that the electric current backward flow from getting into switch tube S0.
Preferably, the resonant DC-DC circuit further includes a switching unit, a resonant capacitor Cr and a transformer, the transformer includes a primary winding N1, a secondary winding M1 and a secondary winding M2, the primary winding N1 and the resonant capacitor Cr are connected in series and then connected to the switching unit, and the other two ends of the switching unit are used as input ends of the resonant DC-DC circuit; the secondary winding M1 is used as a constant voltage output end through a first rectified output end after rectification, and the secondary winding M2 is used as a constant current output end through a second rectified output end after rectification. The secondary winding M1 and the secondary winding M2 are transformed by a transformer, so that the circuit generates two paths of output.
Preferably, the coupling coefficient between the secondary winding M1 and the primary winding N1 is greater than the coupling coefficient between the secondary winding M2 and the primary winding N1. According to different coupling coefficients of the secondary winding M1, the secondary winding M2 and the primary winding N1, the resonant DC-DC circuit generates multiple paths of different outputs.
Preferably, the switch unit in the resonant DC-DC circuit comprises a switch tube S1 and a switch tube S2; the resonant DC-DC circuit further includes a diode D2, a diode D3, a diode D4, a diode D5, a capacitor C1, a capacitor C2, and a resistor Rs, wherein a first end of the switching tube S1 is used as an input positive terminal of the resonant DC-DC circuit, a second end of the switching tube S1 is respectively connected to the first end of the switching tube S2 and one end of the primary winding N1, a second end of the switching tube 2 is used as an input negative terminal of the resonant DC-DC circuit and is connected to one end of the resonant capacitor Cr, the other end of the resonant capacitor Cr is connected to the other end of the primary winding N1, the secondary winding M1 and the secondary winding M2 have tap terminals, the first end of the secondary winding M1 is connected to the anode of the diode D2, the second end of the secondary winding M1 is connected to the anode of the diode D2 via the diode D3, the cathode of the diode D5 is connected to the tap terminal 1 of the secondary winding M1, two ends of the capacitor C1 are used as the constant voltage output end; a first end of the secondary winding M2 is connected to an anode of the diode D4, a second end of the secondary winding M2 is connected to an anode of the diode D4 through the diode D5, a cathode of the diode D4 is connected to a first end of the capacitor C2, a tap end of the secondary winding M2 is connected to a second end of the capacitor C2 and a first end of the resistor Rs, two ends of the capacitor C2 are used as the constant current output end, and a second end of the resistor Rs is connected to the current regulating circuit. The LLC half-bridge resonant circuit is composed of a switching tube S1, a switching tube S2, a resonant capacitor Cr, a diode D2, a diode D3, a diode D4, a diode D5 and a transformer, direct current output by the PFC main circuit is converted into alternating current, voltage conversion is carried out through the transformer, coupling coefficients of two secondary windings and a primary winding of the transformer are different, voltage and current output by the resonant DC-DC circuit are different, output power of most outputs is different, alternating current is converted into direct current through half-bridge rectification composed of the diode D2, the diode D3, the diode D4 and the diode D5 after voltage transformation is carried out through the transformer, and the direct current is supplied to an LED lamp after voltage stabilization is carried out through the capacitor C1 and the capacitor C2.
Preferably, the voltage regulation circuit includes an operational amplifier U1, a resistor R1, a resistor R2, a resistor R3, and a capacitor C4, wherein a negative phase input terminal of the operational amplifier U1 is connected to a first terminal of the capacitor C4, a first terminal of the resistor R1, and a first terminal of the resistor R2, another terminal of the resistor R1 is connected to a first terminal of the capacitor C1, another terminal of the resistor R2 is connected to a second terminal of the capacitor C1, a second terminal of the capacitor C4 is connected to an output terminal of the operational amplifier U1 via the resistor R3, and a positive phase input terminal of the operational amplifier U1 receives the voltage reference signal Vref 1. The operational amplifier U1 compares the detected voltage signal with the voltage reference signal Vref1, and outputs a second feedback signal to the drive control circuit through the isolation circuit according to the comparison result, and the capacitor C1, the resistor R3 and the operational amplifier form negative feedback regulation.
Preferably, the isolation circuit comprises a photoelectric coupler, an input end of the photoelectric coupler is connected with the voltage regulating circuit, and an output end of the photoelectric coupler is connected with the driving control circuit. The voltage regulating circuit and the drive control circuit are isolated through the photoelectric coupler, and the interference of high-frequency signals to the circuit is prevented.
Preferably, the current regulation circuit comprises an operational amplifier U2, a capacitor C5 and a resistor R4, wherein a negative phase input terminal of the operational amplifier U2 is connected to a first terminal of the capacitor C5 and a second terminal of the resistor Rs, respectively, a second terminal of the capacitor C5 is connected to an output terminal of the operational amplifier U2 through a resistor R4, and a positive phase input terminal of the operational amplifier is inputted with the current reference signal Iref 1. The operational amplifier U2 compares the detected current signal with the current reference signal Iref1, and outputs a first feedback signal to the frequency control driving circuit according to the comparison result, and the operational amplifier U2, the capacitor C5 and the resistor R4 form negative feedback regulation.
Preferably, the frequency control driving circuit includes a resonant control chip, a voltage-controlled oscillator and a driving circuit, the voltage-controlled oscillator receives the first feedback signal transmitted by the current regulating circuit, determines the frequency of the switching tube S1 and the switching tube S2 according to the magnitude of the first feedback signal, transmits the frequency signal to the resonant control chip, and the resonant control chip generates a driving signal according to the frequency signal through the driving circuit and outputs the driving signal to the switching tube S1 and the switching tube S2. The resonance control chip receives a first feedback signal output by the current regulating circuit, and controls the conduction and the cut-off of the MOS tube Q1 and the MOS tube Q2 according to the first feedback signal, so that the current output of the resonance DC-DC circuit is stable and the current reference signal Iref1 is ensured, and the constant current output of the circuit is ensured.
Preferably, the driving control circuit includes a PFC control chip, an operational amplifier U3, an operational amplifier U4 and an RS flip-flop a1, wherein a positive phase input terminal of the operational amplifier U3 and a negative phase input terminal of the operational amplifier U4 input the second feedback signal transmitted by the voltage regulating circuit, a negative phase input terminal of the operational amplifier U3 inputs a voltage reference signal Vref2, an output terminal of the operational amplifier U3 is connected to the S terminal of the RS flip-flop a1, a positive phase input terminal of the operational amplifier U4 inputs a voltage reference signal Vref3, an output terminal of the operational amplifier U4 is connected to the R terminal of the RS flip-flop a1, a Q terminal and a Q terminal of the RS flip-flop a1 are both connected to the PFC control chip, and the PFC control chip is connected to the switching tube S0. The PFC control chip controls the switch tube S0 according to the output result of the RS trigger, so that the output voltage of the PFC main circuit is stabilized at a voltage reference signal Vref1, and the constant voltage output of the circuit is realized.
The invention has the beneficial effects that: (1) the LED driver is used for realizing multi-path output through different coupling coefficients of two secondary windings and a primary winding of the transformer; (2) the constant voltage output of the LED driver is realized by the detection of the voltage and the regulation of the drive control circuit by the voltage regulating circuit; (3) the constant current output of the LED driver is realized by the detection of the current regulating circuit on the current and the regulation of the frequency control driving circuit.
Drawings
Fig. 1 is a schematic structural diagram of an LED driver according to a first embodiment.
Fig. 2 is a schematic diagram of an LED driver circuit according to the first embodiment.
Fig. 3 is a schematic diagram of a voltage regulating circuit according to a first embodiment.
Fig. 4 is a schematic diagram of a current regulating circuit according to the first embodiment.
In the figure, 1, a power supply, 2, a PFC main circuit, 3, a resonant DC-DC circuit, 4, a current regulating circuit, 5, a voltage regulating circuit, 6, a frequency control driving circuit, 7, an isolation circuit and 8, a driving control circuit.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.
The first embodiment is as follows: an LED driver comprises a PFC main circuit 2, a drive control circuit 8, an isolation circuit 7, a voltage regulation circuit 5, a frequency control drive circuit 6, a current regulation circuit 4 and a resonant DC-DC circuit 3, wherein the input end of the PFC main circuit 2 is used as the input end of the LED driver and is used for being connected with a power supply 1, the output end of the PFC main circuit 2 is connected with the input end of the resonant DC-DC circuit 3, the output end of the resonant DC-DC circuit 3 comprises a constant voltage output end and a constant current output end, the input end of the current regulation circuit 4 is connected with the constant current output end of the resonant DC-DC circuit 3, the output end of the current regulation circuit 4 is connected with the frequency control drive circuit 6, the current regulation circuit 4 is used for detecting the current output by the constant current output end and outputting a first feedback signal to the frequency control drive circuit 6, and the frequency control drive circuit 6 outputs a first drive signal to the resonant DC-DC circuit according to The circuit 3 maintains the constant current output by the constant current output end through the working frequency of the resonant DC-DC circuit 3, the input end of the voltage regulating circuit 5 is connected with the constant voltage output end of the resonant DC-DC circuit 3, the output end of the voltage regulating circuit 5 is connected with the drive control circuit 8 through the isolation circuit, the voltage regulating circuit 5 is used for detecting the voltage output by the constant voltage output end and outputting a second feedback signal to the drive control circuit 8 through the isolation circuit, and the drive control circuit 8 outputs a second drive signal to the PFC main circuit 2 according to the size of the second feedback signal to enable the output voltage to be constant, so that the voltage of the constant voltage output end is constant.
As shown in fig. 2, the PFC main circuit 2 includes an inductor L, a switching tube S0, a diode D1, and a capacitor C0, one end of the inductor L is connected to the positive electrode of the power supply 1, the other end of the inductor L is connected to one end of the switching tube S0 and the anode of the diode D1, the other end of the switching tube S0 is connected to one end of a capacitor C0 and the negative electrode of the power supply 1, the other end of the capacitor C0 is connected to the cathode of the diode D1, and both ends of the capacitor C0 are connected to the resonant DC-DC circuit 3 as the output end of the PFC main circuit 2.
The resonant DC-DC circuit 3 comprises a switch unit, a resonant capacitor Cr, a transformer, a diode D2, a diode D3, a diode D4, a diode D5, a capacitor C1, a capacitor C2 and a resistor Rs, wherein the transformer comprises a primary winding N1, a secondary winding M1 and a secondary winding M2, the primary winding N1 and the resonant capacitor Cr are connected in series and then connected with the switch unit, and the other two ends of the switch unit are used as input ends of the resonant DC-DC circuit; the secondary winding M1 is used as a constant voltage output end through a first rectified output end after rectification, the secondary winding M2 is used as a constant current output end through a second rectified output end after rectification, the coupling coefficient of the secondary winding M1 and the primary winding N1 is larger than that of the secondary winding M2 and the primary winding N1, the switching unit comprises a switching tube S1 and a switching tube S2, the first end of the switching tube S1 is used as the input positive end of the resonant DC-DC circuit, the second end of the switching tube S1 is respectively connected with the first end of the switching tube S2 and one end of the primary winding N1, the second end of the switching tube S2 is used as the input negative end of the resonant DC-DC circuit and is connected with one end of a resonant capacitor Cr, the other end of the resonant capacitor Cr is connected with the other end of the primary winding N1, the secondary winding M1 and the secondary winding M2 are provided with tapped ends, the first end of the secondary winding M1 is connected with the anode of the diode D2, the second end of the secondary winding M1 is connected with the anode of a diode D2 through a diode D3, the cathode of the diode D2 and the tapping end of the secondary winding M1 are connected with a capacitor C1, and two ends of a capacitor C1 are used as constant-voltage output ends; the first end of the secondary winding M2 is connected with the anode of the diode D4, the second end of the secondary winding M2 is connected with the anode of the diode D4 through the diode D5, the cathode of the diode D4 is connected with the first end of the capacitor C2, the tapping end of the secondary winding M2 is respectively connected with the second end of the capacitor C2 and the first end of the resistor Rs, two ends of the capacitor C2 serve as constant current output ends, and the second end of the resistor Rs is connected with the current regulating circuit 4.
The isolation circuit 7 comprises a photoelectric coupler, the input end of the photoelectric coupler is connected with the voltage regulating circuit 5, and the output end of the photoelectric coupler is connected with the drive control circuit 8.
The frequency control driving circuit 6 comprises a resonance control chip, a voltage-controlled oscillator and a driving circuit, the voltage-controlled oscillator receives the first feedback signal transmitted by the current regulating circuit 4, determines the frequency of the switching tube S1 and the switching tube S2 according to the first feedback signal, transmits the frequency signal to the resonance control chip, and the resonance control chip generates a driving signal through the driving circuit according to the frequency signal and outputs the driving signal to the switching tube S1 and the switching tube S2.
The driving control circuit 8 comprises a PFC control chip, an operational amplifier U3, an operational amplifier U4 and an RS flip-flop a1, wherein a positive phase input end of the operational amplifier U3 and a negative phase input end of the operational amplifier U4 input the second feedback signal transmitted by the voltage regulating circuit 5, a negative phase input end of the operational amplifier U3 inputs a voltage reference signal Vref2, an output end of the operational amplifier U3 is connected with an S end of the RS flip-flop a1, a positive phase input end of the operational amplifier U4 inputs the voltage reference signal Vref3, an output end of the operational amplifier U4 is connected with an R end of the RS flip-flop a1, a Q end and a Q-bar end of the RS flip-flop a1 are both connected with the PFC control chip, and the PFC control chip is connected with the switching tube S0.
As shown in fig. 3, the voltage regulator circuit 5 includes an operational amplifier U1, a resistor R1, a resistor R2, a resistor R3, and a capacitor C4, wherein a negative phase input terminal of the operational amplifier U1 is connected to a first terminal of a capacitor C4, one terminal of a resistor R1, and one terminal of a resistor R2, another terminal of a resistor R1 is connected to a first terminal of a capacitor C1, another terminal of a resistor R2 is connected to a second terminal of the capacitor C1, a second terminal of a capacitor C4 is connected to an output terminal of the operational amplifier U1 via a resistor R3, and a positive phase input terminal of the operational amplifier U1 receives a voltage reference signal Vref 1.
As shown in fig. 4, the current regulating circuit 4 includes an operational amplifier U2, a capacitor C5, and a resistor R4, wherein a negative phase input terminal of the operational amplifier U2 is connected to a first terminal of the capacitor C5 and a second terminal of the resistor Rs, a second terminal of the capacitor C5 is connected to an output terminal of the operational amplifier U2 through a resistor R4, and a positive phase input terminal of the operational amplifier is inputted with the current reference signal Iref 1.
In specific application, 220V alternating current enters a PFC main circuit 2 through a power supply 1 after being rectified by a rectifying circuit, the amplitude of input voltage of the PFC main circuit 2 is changed in a sine mode, a Boost circuit is formed by an inductor L, a switching tube S0 and a diode D1, and the input current of the Boost circuit is close to the input voltage, namely close to a sine wave through control of a drive control circuit, so that the PFC function is achieved. The PFC main circuit 2 realized by a Boost circuit outputs direct current voltage Vbus under the control of a voltage regulating circuit 5 and a drive control circuit 8, the direct current voltage Vbus with relatively stable amplitude is input into a resonant DC-DC circuit 3, a switching tube S1, a switching tube S2, a resonant capacitor Cr, a diode D2, a diode D3, a diode D4, a diode D5 and a transformer in the resonant DC-DC circuit 3 form an LLC half-bridge resonant circuit, the voltage output by the PFC main circuit 2 is subjected to DC-DC conversion, the coupling coefficients of two secondary windings and a primary winding of the transformer are different, a secondary winding M1 is tightly coupled with the primary winding N1, the relevance between the voltage output by a first path and the primary winding N1 of the transformer of the resonant DC-DC circuit 3 is high, the switching tube S0 of the PFC main circuit 2 is controlled by the voltage regulating circuit 5 and the drive control circuit 8, the value of the output voltage Vbus of the PFC main circuit 2 is regulated by controlling the switching tube S0, the value of the output voltage Vbus of the PFC main circuit 2 is stabilized at the value set by the voltage reference signal Vref1, the first output voltage of the resonant DC-DC circuit 3 is stabilized at a certain value, the constant voltage output of the LED driver is realized, the coupling degree of the secondary winding M2 and the primary winding N1 is low, large leakage inductance exists, the switching tube S1 and the switching tube S2 of the resonant DC-DC circuit 3 are controlled through the current adjusting circuit 4 and the frequency control driving circuit 6, the second output current is stabilized at the current reference signal Iref1, the second output current of the resonant DC-DC circuit 3 is stabilized at a certain value, the constant current output of the LED driver is realized, and further, the constant voltage output and the constant current output are realized when the same LED driver outputs in multiple paths.
The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.
Claims (10)
1. An LED driver, comprising:
the LED driving circuit comprises a PFC main circuit, a driving control circuit, an isolation circuit, a voltage regulating circuit, a frequency control driving circuit, a current regulating circuit and a resonant DC-DC circuit, wherein the input end of the PFC main circuit is used as the input end of the LED driver and is used for being connected with a power supply, the output end of the PFC main circuit is connected with the input end of the resonant DC-DC circuit, the output end of the resonant DC-DC circuit comprises a constant voltage output end and a constant current output end, the input end of the current regulating circuit is connected with the constant current output end, the output end of the current regulating circuit is connected with the frequency control driving circuit, the current regulating circuit is used for detecting the current output by the constant current output end and outputting a first feedback signal to the frequency control driving circuit, and the frequency control driving circuit outputs a first driving signal to the resonant DC-DC circuit according to the magnitude of the, the working frequency of the resonant DC-DC circuit is used for maintaining the constant current output by the constant current output end, the input end of the voltage regulating circuit is connected with the constant voltage output end, the output end of the voltage regulating circuit is connected with the drive control circuit through an isolation circuit, the voltage regulating circuit is used for detecting the voltage output by the constant voltage output end and outputting a second feedback signal to the drive control circuit through the isolation circuit, and the drive control circuit outputs a second drive signal to the PFC main circuit according to the magnitude of the second feedback signal to enable the output voltage of the PFC main circuit to be constant, so that the voltage of the constant voltage output end is constant.
2. The LED driver as claimed in claim 1, wherein the main PFC circuit comprises an inductor L, a switch tube S0, a diode D1 and a capacitor C0, one end of the inductor L is connected to a positive power supply terminal, the other end of the inductor L is connected to one end of the switch tube S0 and an anode of the diode D1, the other end of the switch tube S0 is connected to one end of the capacitor C0 and a negative power supply terminal, the other end of the capacitor C0 is connected to a cathode of the diode D1, and two ends of the capacitor C0 are connected to the resonant DC-DC circuit as an output terminal of the main PFC circuit.
3. The LED driver as claimed in claim 1, wherein the resonant DC-DC circuit further comprises a switching unit, a resonant capacitor Cr and a transformer, the transformer comprises a primary winding N1, a secondary winding M1 and a secondary winding M2, the primary winding N1 and the resonant capacitor Cr are connected in series and then connected to the switching unit, and the other two ends of the switching unit are used as input ends of the resonant DC-DC circuit; the secondary winding M1 is used as a constant voltage output end through a rectified first end rectification output end, and the secondary winding M2 is used as a constant current output end through a rectified second rectification output end.
4. The LED driver as claimed in claim 3, wherein the coupling coefficient of the secondary winding M1 to the primary winding N1 is greater than the coupling coefficient of the secondary winding M2 to the primary winding N1.
5. The LED driver of claim 3, wherein the switch unit in the resonant DC-DC circuit comprises a switch tube S1 and a switch tube S2; the resonant DC-DC circuit further includes a diode D2, a diode D3, a diode D4, a diode D5, a capacitor C1, a capacitor C2, and a resistor Rs, wherein a first end of the switching tube S1 is used as an input positive terminal of the resonant DC-DC circuit, a second end of the switching tube S1 is respectively connected to the first end of the switching tube S2 and one end of the primary winding N1, a second end of the switching tube 2 is used as an input negative terminal of the resonant DC-DC circuit and is connected to one end of the resonant capacitor Cr, the other end of the resonant capacitor Cr is connected to the other end of the primary winding N1, the secondary winding M1 and the secondary winding M2 have tap terminals, the first end of the secondary winding M1 is connected to the anode of the diode D2, the second end of the secondary winding M1 is connected to the anode of the diode D2 via the diode D3, the cathode of the diode D5 is connected to the tap terminal 1 of the secondary winding M1, two ends of the capacitor C1 are used as the constant voltage output end; a first end of the secondary winding M2 is connected to an anode of the diode D4, a second end of the secondary winding M2 is connected to an anode of the diode D4 through the diode D5, a cathode of the diode D4 is connected to a first end of the capacitor C2, a tap end of the secondary winding M2 is connected to a second end of the capacitor C2 and a first end of the resistor Rs, two ends of the capacitor C2 are used as the constant current output end, and a second end of the resistor Rs is connected to the current regulating circuit.
6. The LED driver as claimed in claim 5, wherein the voltage regulation circuit comprises an operational amplifier U1, a resistor R1, a resistor R2, a resistor R3 and a capacitor C4, wherein a negative phase input terminal of the operational amplifier U1 is connected to a first terminal of the capacitor C4, a first terminal of the resistor R1 and a first terminal of the resistor R2, the other terminal of the resistor R1 is connected to a first terminal of the capacitor C1, the other terminal of the resistor R2 is connected to a second terminal of the capacitor C1, a second terminal of the capacitor C4 is connected to an output terminal of the operational amplifier U1 via the resistor R3, and a positive phase input terminal of the operational amplifier U1 is inputted with a voltage reference signal Vref 1.
7. The LED driver as claimed in claim 1, wherein the isolation circuit comprises a photo coupler, an input terminal of the photo coupler is connected to the voltage regulating circuit, and an output terminal of the photo coupler is connected to the driving control circuit.
8. The LED driver as claimed in claim 5, wherein the current regulation circuit comprises an operational amplifier U2, a capacitor C5 and a resistor R4, wherein the negative phase input terminal of the operational amplifier U2 is connected to the first terminal of the capacitor C5 and the second terminal of the resistor Rs respectively, the second terminal of the capacitor C5 is connected to the output terminal of the operational amplifier U2 through a resistor R4, and the positive phase input terminal of the operational amplifier inputs the current reference signal Iref 1.
9. The LED driver as claimed in claim 5, wherein the frequency control driving circuit includes a resonant control chip, a voltage-controlled oscillator and a driving circuit, the voltage-controlled oscillator receives the first feedback signal from the current regulating circuit and determines the magnitudes of the frequencies of the switch tube S1 and the switch tube S2 according to the magnitude of the first feedback signal, and transmits a frequency signal to the resonant control chip, and the resonant control chip generates a driving signal according to the frequency signal by the driving circuit and outputs the driving signal to the switch tube S1 and the switch tube S2.
10. The LED driver as claimed in claim 2, wherein the driving control circuit comprises a PFC control chip, an operational amplifier U3, an operational amplifier U4 and an RS trigger A1, wherein the positive phase input terminal of the operational amplifier U3 and the negative phase input terminal of the operational amplifier U4 input the second feedback signal transmitted by the voltage regulation circuit, the negative phase input terminal of the operational amplifier U3 inputs a voltage reference signal Vref2, the output terminal of the operational amplifier U3 is connected to the S terminal of the RS trigger A1, the positive phase input terminal of the operational amplifier U4 inputs the voltage reference signal Vref3, the output terminal of the operational amplifier U4 is connected to the R terminal of the RS trigger A1, the Q terminal and the QNOT terminal of the RS trigger A1 are both connected to the PFC control chip, and the PFC control chip is connected to the switch tube S0.
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| CN201911083031.7A CN110798938A (en) | 2019-11-07 | 2019-11-07 | LED driver |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911083031.7A CN110798938A (en) | 2019-11-07 | 2019-11-07 | LED driver |
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| CN110798938A true CN110798938A (en) | 2020-02-14 |
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| CN112511006A (en) * | 2020-11-02 | 2021-03-16 | 杭州乐图电子科技有限公司 | Double-path resonance conversion circuit and control method |
| CN113436571A (en) * | 2020-03-18 | 2021-09-24 | 海信视像科技股份有限公司 | Display device and power supply circuit |
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