CN106787854B - LED driving circuit - Google Patents
LED driving circuit Download PDFInfo
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- CN106787854B CN106787854B CN201710117982.6A CN201710117982A CN106787854B CN 106787854 B CN106787854 B CN 106787854B CN 201710117982 A CN201710117982 A CN 201710117982A CN 106787854 B CN106787854 B CN 106787854B
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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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal 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
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal 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
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Abstract
The invention provides an LED driving circuit, which comprises: a high-frequency pulse current source, an isolation transformer and a secondary side rectifying circuit; the isolation transformer includes: a first winding and a second winding; the high-frequency pulse current source is connected with the first winding; the secondary side rectifying circuit includes: the first load loop and the second load loop which are alternately conducted, the first drive control circuit, the second drive control circuit, the first capacitor and the first diode; the first load loop comprises a first synchronous rectifier tube, and the second load loop comprises a second synchronous rectifier tube; the first synchronous rectifying tube and the second synchronous rectifying tube are alternately conducted; the direct current power supply supplies power to the first drive control circuit through the first capacitor and the first diode, and directly supplies power to the second drive control circuit. The LED driving circuit can solve the problems of large on-state loss and power supply of the driving control circuit of the synchronous rectifying tube.
Description
Technical Field
The invention relates to the technical field of LED driving circuits, in particular to an LED driving circuit.
Background
A common switching power supply driven by a dc load includes: the high-frequency pulse current source, the isolation transformer and the rectifying circuit are arranged on the secondary side of the isolation transformer. Wherein the high-frequency pulse current source is controlled by a high-frequency switch; the secondary side rectifying circuit is in the form of a full-bridge rectifying circuit or a voltage doubling rectifying circuit and the like.
In the prior art, the secondary rectifying circuit adopts diodes as rectifying devices, but the on-state loss of the diodes is large under the condition of large output current due to high conduction voltage drop of the diodes, so that the efficiency of the circuit in the switching power supply is low.
The problem of large on-state loss is solved by introducing the synchronous rectifying tube as the rectifying device, but the synchronous rectifying tube needs a drive control circuit for working, and the drive control circuit cannot be powered by using the same direct current power supply source due to the difference of reference ends.
Therefore, how to provide a driving circuit capable of solving the problem of large on-state loss and the problem of power supply of all driving control circuits is a problem to be solved by those skilled in the art.
Disclosure of Invention
In order to solve the problems, the invention provides an LED driving circuit, which solves the problem of large on-state loss caused by a diode serving as a rectifying device and solves the power supply problem of different driving control circuits.
In order to achieve the above purpose, the present invention provides the following technical solutions:
an LED driving circuit comprising: a high-frequency pulse current source, an isolation transformer and a secondary side rectifying circuit;
Wherein, the isolation transformer includes: a first winding and a second winding; the high-frequency pulse current source is connected with the first winding;
the secondary side rectifying circuit includes: a first load circuit and a second load circuit which alternately operate; the first load loop comprises a first synchronous rectifier tube, and the second load loop comprises a second synchronous rectifier tube; the first synchronous rectifying tube and the second synchronous rectifying tube are alternately conducted; the secondary rectifying circuit further comprises a first driving control circuit for driving the first synchronous rectifying tube, a second driving control circuit for driving the second synchronous rectifying tube, a first capacitor and a first diode;
the source electrode of the first synchronous rectifying tube is connected with the first end of the second winding and is used as the input end of the first load loop; the drain electrode of the first synchronous rectifying tube is an output positive end; an output of the first load loop is connected to a second end of the second winding;
the input end of the second load loop is connected with the second end of the second winding, and the drain electrode of the second synchronous rectifying tube is connected with the first end of the second winding and used as the output end of the second load loop; the source electrode of the second synchronous rectifying tube is an output ground end;
The reference end of the first drive control circuit is connected with the source electrode of the first synchronous rectifying tube;
the reference end of the second drive control circuit is connected with the source electrode of the second synchronous rectifying tube; the power supply end of the second drive control circuit is connected with a direct current power supply, and the grounding end of the direct current power supply is a reference end of the second drive control circuit;
the anode of the first diode is connected with the direct current power supply, and the cathode of the first diode is connected with the power supply end of the first drive control circuit; one end of the first capacitor is connected with the power supply end of the first drive control circuit, and the other end of the first capacitor is connected with the reference end of the first drive control circuit.
Preferably, in the above LED driving circuit, the first driving control circuit includes: the first processing unit and the first detection unit; the first detection unit is connected with the first synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the first synchronous rectifying tube and sending a detection result to the first processing unit;
the first processing unit is used for generating a driving signal according to the detection result; and transmitting the driving signal to the gate of the first synchronous rectifier tube;
The second drive control circuit includes: the second processing unit and the second detection unit;
the second detection unit is connected with the second synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the second synchronous rectifying tube and sending a detection result to the second processing unit;
the second processing unit is used for generating a driving signal according to the detection result; and transmitting the driving signal to the grid electrode of the second synchronous rectifying tube.
Preferably, in the above LED driving circuit, when the first detecting unit detects that the source-drain voltage of the first synchronous rectifier tube is a forward conduction voltage, the first processing unit generates a first conduction driving signal; when the first detection unit detects that the source-drain voltage forward voltage drop of the first synchronous rectifying tube is zero or is reverse voltage drop, the first processing unit generates a first turn-off driving signal;
when the second detection unit detects that the source-drain voltage of the second synchronous rectifier tube is forward conduction voltage, the second processing unit generates a second conduction driving signal; and when the second detection unit detects that the source-drain voltage forward voltage drop of the second synchronous rectifying tube is zero or the reverse voltage drop, the second processing unit generates a second turn-off driving signal.
Preferably, in the above LED driving circuit, the first load loop further includes a third capacitor, and the second load loop further includes a second capacitor;
in the first load loop, one end of the third capacitor is an output end of the first load loop and is connected with a second end of the second winding; the other end of the third capacitor is connected with the output ground end;
in the second load loop, one end of the second capacitor is an input end of the second load loop and is connected with a second end of the second winding; the other end of the second capacitor is connected with the output positive end.
Preferably, in the above LED driving circuit, the first load circuit further includes a fourth synchronous rectifier, and the second load circuit further includes a third synchronous rectifier;
the secondary side rectifying circuit further comprises a fourth driving control circuit for driving the fourth synchronous rectifying tube, a third driving control circuit for driving the third synchronous rectifying tube, a second diode and a fourth capacitor; the first synchronous rectifying tube and the fourth synchronous rectifying tube are synchronously conducted, and the second synchronous rectifying tube and the third synchronous rectifying tube are synchronously conducted;
In the first load loop, the drain electrode of the fourth synchronous rectifying tube is an output end of the first load loop and is connected with the second end of the second winding, and the source electrode of the fourth synchronous rectifying tube is connected with the output ground end;
in the second load loop, the source of the third synchronous rectifier tube is the input end of the second load loop and is connected with the second end of the second winding, and the drain electrode of the third synchronous rectifier tube is connected with the output positive end;
the reference end of the third driving control circuit is connected with the source electrode of the third synchronous rectifying tube; the output end of the third driving control circuit is connected with the grid electrode of the third synchronous rectifying tube; the anode of the second diode is connected with the direct current power supply, and the cathode of the second diode is connected with the power supply end of the third drive control circuit; one end of the fourth capacitor is connected with the power supply end of the third drive control circuit; the other end of the fourth capacitor is connected with the reference end of the third driving control circuit;
the reference end of the fourth driving control circuit is connected with the source electrode of the fourth synchronous rectifying tube; the output end of the fourth driving control circuit is connected with the grid electrode of the fourth synchronous rectifying tube; and the power supply end of the fourth drive control circuit is connected with the direct current power supply.
Preferably, in the above LED driving circuit, the third driving control circuit includes: a third processing unit and a third detecting unit;
the third detection unit is connected with the third synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the third synchronous rectifying tube and sending a detection result to the third processing unit;
the third processing unit is used for generating a driving signal according to the detection result and sending the driving signal to the grid electrode of the third synchronous rectifying tube;
the fourth drive control circuit includes: a fourth processing unit and a fourth detecting unit;
the fourth detection unit is connected with the fourth synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the fourth synchronous rectifying tube and sending a detection result to the fourth processing unit;
the fourth processing unit is used for generating a driving signal according to the detection result and sending the driving signal to the grid electrode of the fourth synchronous rectifying tube;
when the third detection unit detects that the source-drain voltage of the third synchronous rectifier tube is forward conduction voltage, the third processing unit generates a third conduction driving signal; when the third detection unit detects that the source-drain voltage forward voltage drop of the third synchronous rectifying tube is zero or is reverse voltage drop, the third processing unit generates a third turn-off driving signal;
When the fourth detection unit detects that the source-drain voltage of the fourth synchronous rectifier tube is forward conduction voltage, the fourth processing unit generates a fourth conduction driving signal; and when the fourth detection unit detects that the forward voltage drop of the source-drain voltage of the fourth synchronous rectifying tube is zero or the reverse voltage drop, the fourth processing unit generates a fourth turn-off driving signal.
Preferably, in the LED driving circuit, the first synchronous rectifier tube and the first driving control circuit are integrated in a first synchronous rectifier;
the first synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the first synchronous rectifier is the source electrode of the first synchronous rectifier; the drain electrode of the first synchronous rectifier is the drain electrode of the first synchronous rectifier, and the power supply end of the first synchronous rectifier is the power supply end of the first drive control circuit;
or the second synchronous rectifier tube and the second driving control circuit are integrated in a second synchronous rectifier;
the second synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the second synchronous rectifier is the source electrode of the second synchronous rectifier; the drain electrode of the second synchronous rectifier is the drain electrode of the second synchronous rectifier, and the power supply end of the second synchronous rectifier is the power supply end of the second drive control circuit.
Preferably, in the above LED driving circuit, the third synchronous rectifier and the third driving control circuit are integrated in a third synchronous rectifier;
the third synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the third synchronous rectifier is the source electrode of the third synchronous rectifier; the drain electrode of the third synchronous rectifier is the drain electrode of the third synchronous rectifier, and the power supply end of the third synchronous rectifier is the power supply end of the third drive control circuit;
or the fourth synchronous rectifier tube and the fourth driving control circuit are integrated in a fourth synchronous rectifier;
the fourth synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the fourth synchronous rectifier is the source electrode of the fourth synchronous rectifier; the drain electrode of the fourth synchronous rectifier is the drain electrode of the fourth synchronous rectifier, and the power supply end of the fourth synchronous rectifier is the power supply end of the fourth drive control circuit.
Preferably, in the LED driving circuit, the dc power supply is an auxiliary source circuit of the LED driving circuit, the isolation transformer further includes a third winding, and an input end of the auxiliary source circuit is connected with the third winding.
Preferably, in the LED driving circuit, the high-frequency pulse current source is an LLC circuit topology or an LCC circuit topology.
As can be seen from the above description, the LED driving circuit provided by the present invention replaces the diode of the rectifying component in the prior art by the first synchronous rectifying tube and the second synchronous rectifying tube, so that the problem of large on-state loss caused by the diode as the rectifying component is solved, and the first driving control circuit and the second driving control circuit are used for conducting the first synchronous rectifying tube and the second synchronous rectifying tube to enable current to flow from the source electrode to the drain electrode, and the current does not pass through the body diode in the first synchronous rectifying tube and the second synchronous rectifying tube, and further the loss is not generated on the body diode.
Meanwhile, the direct current power supply supplies power to the first drive control circuit through the first capacitor and the first diode, and directly supplies power to the second drive control circuit, so that the power supply problem of different drive control circuits is solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings can be obtained according to the provided drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of an LED driving circuit in the prior art;
fig. 2 is a schematic structural diagram of an LED driving circuit according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of another LED driving circuit according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another LED driving circuit according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a driving control circuit according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a synchronous rectifier according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of another LED driving circuit according to an embodiment of the present invention;
fig. 8 is a schematic diagram of another LED driving circuit according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, fig. 1 is a schematic diagram of an LED driving circuit according to the prior art. In the prior art, the secondary rectifying circuit adopts diodes as rectifying devices, but the on-state loss of the diodes is large under the condition of large output current due to high conduction voltage drop of the diodes, so that the efficiency of the circuit in the switching power supply is low.
The problem of large on-state loss is solved by introducing the synchronous rectifying tube as the rectifying device, but the synchronous rectifying tube needs a drive control circuit for working, and the drive control circuit cannot be powered by using the same direct current power supply source due to the difference of reference ends.
Therefore, how to provide a driving circuit capable of solving the problem of large on-state loss and the problem of power supply of all driving control circuits is a problem to be solved by those skilled in the art.
In order to solve the above-described problems, the present invention provides an LED driving circuit including: a high-frequency pulse current source, an isolation transformer and a secondary side rectifying circuit;
wherein, the isolation transformer includes: a first winding and a second winding; the high-frequency pulse current source is connected with the first winding;
The secondary side rectifying circuit includes: a first load circuit and a second load circuit which alternately operate; the first load loop comprises a first synchronous rectifier tube, and the second load loop comprises a second synchronous rectifier tube; the first synchronous rectifying tube and the second synchronous rectifying tube are alternately conducted; the secondary rectifying circuit further comprises a first driving control circuit for driving the first synchronous rectifying tube, a second driving control circuit for driving the second synchronous rectifying tube, a first capacitor and a first diode;
the source electrode of the first synchronous rectifying tube is connected with the first end of the second winding and is used as the input end of the first load loop; the drain electrode of the first synchronous rectifying tube is an output positive end; an output of the first load loop is connected to a second end of the second winding;
the input end of the second load loop is connected with the second end of the second winding, and the drain electrode of the second synchronous rectifying tube is connected with the first end of the second winding and used as the output end of the second load loop; the source electrode of the second synchronous rectifying tube is an output ground end;
the reference end of the first drive control circuit is connected with the source electrode of the first synchronous rectifying tube;
The anode of the first diode is connected with the direct current power supply, and the cathode of the first diode is connected with the power supply end of the first drive control circuit; one end of the first capacitor is connected with a power supply end of the first drive control circuit, the other end of the first capacitor is connected with a reference end of the first drive control circuit, and the first capacitor is used for supplying power to the first drive control circuit;
the reference end of the second drive control circuit is connected with the source electrode of the second synchronous rectifying tube; the power supply end of the second drive control circuit is connected with a direct current power supply, the grounding end of the direct current power supply is the reference end of the second drive control circuit, and when the second synchronous rectifying tube is conducted, the direct current power supply charges the first capacitor through the first diode.
The LED driving circuit comprises an LED load, an LED driving circuit and a ground end GND, wherein the positive end of the output of the LED driving circuit is connected with the positive electrode of the LED load, and the ground end GND is connected with the negative electrode of the LED load.
It should be noted that, the reference end of the dc power supply in the present application is the output ground end of the LED driving circuit; meanwhile, the direct current power supply can be a direct current power supply generated in the LED driving circuit, can also be a direct current power supply input from the outside of the LED driving circuit, and is not limited in the application.
In this application, the "input end" of the load circuit refers to an end of the load circuit into which a current flows, and the "output end" of the load circuit refers to an end of the load circuit from which a current flows.
As can be seen from the above description, the LED driving circuit provided by the present invention replaces the diode of the rectifying component in the prior art by the first synchronous rectifying tube and the second synchronous rectifying tube, so that the problem of large on-state loss caused by the diode as the rectifying component is solved, and the first driving control circuit and the second driving control circuit are used for conducting the first synchronous rectifying tube and the second synchronous rectifying tube to enable current to flow from the source electrode to the drain electrode, and the current does not pass through the body diode in the first synchronous rectifying tube and the second synchronous rectifying tube, and further the loss is not generated on the body diode.
Meanwhile, the direct current power supply supplies power to the first drive control circuit through the first capacitor and the first diode, and directly supplies power to the second drive control circuit, so that the power supply problem of different drive control circuits is solved.
In order to better explain the embodiments of the present invention, the embodiments provided by the present invention are specifically explained below with reference to the figures.
Referring to fig. 2, fig. 2 is a schematic structural diagram of an LED driving circuit according to an embodiment of the present invention.
The LED driving circuit includes: a high-frequency pulse current source 11, an isolation transformer T and a secondary side rectifying circuit;
the isolation transformer T includes: a first winding S1 and a second winding S2; and the high-frequency pulse current source 11 is connected with the first winding S1;
the high-frequency pulse current source 11 is implemented for various circuit topologies such as LLC or LCC, and is an ac source, but is not limited in the present invention.
The secondary side rectifying circuit includes: a first load circuit and a second load circuit which alternately operate; the first load loop comprises a first synchronous rectifying tube Q1, and the second load loop comprises a second synchronous rectifying tube Q2; the first synchronous rectifying tube Q1 and the second synchronous rectifying tube Q2 are alternately conducted; the secondary rectifying circuit further comprises a first driving control circuit 13 for driving the first synchronous rectifying tube Q1, a second driving control circuit 14 for driving the second synchronous rectifying tube Q2, a first capacitor C1 and a first diode D1;
wherein, the source VS of the first synchronous rectifier Q1 and the reference terminal GND1 of the first driving control circuit 13 are used as the input terminal H1-1 of the first load loop; the drain electrode VD of the first synchronous rectifying tube Q1 is an output positive end; the output end H1-2 of the first load loop is connected to the second end S2-1 of the second winding S2;
The input end H2-1 of the second load loop is connected with the second end S2-2 of the second winding S2, and the drain electrode VD of the second synchronous rectifier tube Q2 is connected with the first end S2-1 of the second winding S2 to serve as the output end H2-2 of the second load loop; the source VS of the second synchronous rectifier Q2 is an output ground GND;
the reference end GND1 of the first driving control circuit 13 is connected to the source VS of the first synchronous rectifier Q1;
the anode of the first diode D1 is connected to the power supply end VCC of the dc power supply 12, and the cathode of the first diode D1 is connected to the power supply end VCC1 of the first drive control circuit 13; one end of the first capacitor C1 is connected to the power supply end VCC1 of the first drive control circuit 13, the other end of the first capacitor C1 is connected to the reference end GND1 of the first drive control circuit 13, and the first capacitor C1 is configured to supply power to the first drive control circuit 13;
the reference end GND2 of the second driving control circuit 14 is connected to the source VS of the second synchronous rectifier Q2; the power supply end VCC2 of the second driving control circuit 14 is connected to the power supply end VCC of the dc power supply 12, the ground end of the dc power supply 12 is the reference end GND2 of the second driving control circuit 14, and when the second synchronous rectifier Q2 is turned on, the dc power supply 12 charges the first capacitor C1 through the first diode D1;
The driving end of the first driving control circuit 13 is connected with the grid VG of the first synchronous rectifying tube Q1; the driving end of the second driving control circuit 14 is connected with the grid VG of the second synchronous rectifying tube Q2; that is, the first synchronous rectifier Q1 and the second synchronous rectifier Q2 both need corresponding driving control circuits to drive;
wherein, the isolation transformer T further comprises: and a third winding S3, and the auxiliary source circuit 121 is connected to the third winding S3, and is configured to obtain energy from the third winding S3.
The LED driving circuit comprises an LED load, an LED driving circuit and a ground end GND, wherein the positive end of the output of the LED driving circuit is connected with the positive electrode of the LED load, and the ground end GND is connected with the negative electrode of the LED load.
As shown in fig. 2, since the source VS of the first synchronous rectifier Q1 is not the output ground GND of the LED driving circuit, the reference point of the driving signal of the first synchronous rectifier Q1 is not the output ground GND of the LED driving circuit, but the source VS of the first synchronous rectifier Q1, and the auxiliary source circuit 121 connected to the ground terminal and the output ground GND cannot supply power to the first driving control circuit 13.
In order to solve the power supply problem of a drive control circuit of a synchronous rectifying tube, namely the problem that two synchronous rectifying tubes which are alternately conducted are not grounded together, the application designs a first diode D1 and a first capacitor C1 by utilizing the characteristic that when a second synchronous rectifying tube Q2 is conducted, the voltage between a source VS of the first synchronous rectifying tube Q1 and an output ground GND is very small, and the voltage is the conduction voltage drop of the second synchronous rectifying tube Q2. When the second synchronous rectifier tube Q2 is turned on, the first diode D1 charges the first capacitor C1 through the direct current power supply 12 with the reference end being the output ground end GND, so that the first capacitor C1 stores enough energy; when the second synchronous rectifying tube Q2 is turned off and the first synchronous rectifying tube Q1 is turned on, the first diode D1 is turned off, and the first capacitor C1 supplies power to the first driving control circuit 13.
The specific working principle is as follows:
when the second end S2-2 of the second winding S2 is positive and the first end S2-1 is negative, the second load loop: s2- & gt H2-1- & gt Cout- & gt Q2- & gt H2- & gt S2-1; at this time, since the second synchronous rectifier Q2 is turned on, the potential at one end of the first capacitor C1 is equal to the potential at the output ground GND of the LED driving circuit (neglecting the conduction voltage drop of the second synchronous rectifier Q2), so the dc power supply 12 charges the first capacitor C1 through the first diode D1, and the first capacitor C1 stores energy.
When the second end S2-2 of the second winding S2 is negative and the first end S2-1 is positive, the first load loop: s2-1- & gt H1- & gt Q1- & gt Cout- & gt H1-2- & gt S2-2; at this time, since the second synchronous rectifier Q2 is turned off, the potential of the first end S2-1 of the second winding S2 is Vo (Vo is the output voltage of the LED driving circuit, i.e., the voltage on Cout), so the potential of the positive end (VCC 1) of the first capacitor C1 is vo+vc1 (Vc 1 is the stored voltage on the first capacitor C1); since the output voltage Vo of the LED driving circuit is generally higher than the supply voltage Vcc of the dc power supply 12, the voltage at the cathode of the first diode D1 is greater than the voltage at the anode of the first diode D1, the first diode D1 is turned off reversely, and the first capacitor C1 supplies power to the first driving control circuit 13, so that the first driving control circuit 13 normally outputs a driving signal.
Note that Cout is represented as a load, and the first load loop and the second load loop include, but are not limited to, the above devices and nodes.
It can be seen that, by connecting the power supply terminal VCC1 of the first driving control circuit 13 with one end of the first capacitor C1, the reference terminal GND1 of the first driving control circuit 13 is connected with the other end of the first capacitor C1, so as to achieve the purpose that the first capacitor C1 supplies power to the first driving control circuit 13.
As is apparent from the above description, the LED driving circuit solves the problem of large on-state loss caused by the use of the diode as the rectifying part, and solves the power supply problem of all driving control circuits by using the synchronous rectifying tube as the rectifying part instead of the diode.
Optionally, the dc power supply 12 is an auxiliary source circuit 121 of the LED driving circuit.
Since the ground terminal of the auxiliary source circuit 121 is connected to the output ground terminal GND of the LED driving circuit, as shown in fig. 3, the output ground terminal GND of the LED driving circuit is the source VS of the second synchronous rectifier Q2, the source VS of the second synchronous rectifier Q2 is connected to the output ground terminal GND of the LED driving circuit, and the reference terminal GND2 of the second driving control circuit 14 is connected to the output ground terminal GND of the LED driving circuit, so that the power supply source of the second driving control circuit 14 may be the auxiliary source circuit 121, and therefore the power supply terminal VCC2 of the second driving control circuit 14 is connected to the output terminal VCC of the auxiliary source circuit 121 for obtaining the power supply. It should be noted that, the auxiliary source circuit 121 may also supply power to other circuit units in the LED driving circuit, such as a loop control unit.
Based on the above embodiments, referring to fig. 3, fig. 3 is a schematic structural diagram of another LED driving circuit according to an embodiment of the present invention. Wherein the second load circuit comprises: a second capacitor C2;
one end of the second capacitor C2 is an input end of the second load loop and is connected with a second end S2-2 of the second winding S2; the other end of the second capacitor C2 is connected with the drain electrode VD of the first synchronous rectifying tube Q1 and is used as an output positive end of the LED driving circuit;
the first load circuit includes: a third capacitor C3;
one end of the third capacitor C3 is an output end of the first load loop and is connected with the second end S2-2 of the second winding S2; the other end of the third capacitor C3 and the reference end GND2 of the second driving control circuit 14 are respectively connected to the source VS of the second synchronous rectifier Q2, and serve as the output ground GND of the LED driving circuit.
At this time, the secondary side rectifying circuit includes: the secondary side rectifying circuit is a voltage doubling synchronous rectifying circuit.
Based on the above embodiments, referring to fig. 4, fig. 4 is a schematic structural diagram of another LED driving circuit according to an embodiment of the present invention. Wherein the second load circuit comprises: a third synchronous rectifier Q3; the first load circuit includes: a fourth synchronous rectifier Q4;
in the first load loop, the drain electrode of the fourth synchronous rectifying tube Q4 is an output end of the first load loop, and is connected with the second end of the second winding, and the source electrode of the fourth synchronous rectifying tube Q4 is connected with the output ground end;
in the second load loop, a source electrode Q3 of the third synchronous rectifying tube is an input end of the second load loop and is connected with a second end of the second winding, and a drain electrode of the third synchronous rectifying tube is connected with the output positive end;
the secondary rectifying circuit further comprises a fourth driving control circuit 42 for driving the fourth synchronous rectifying tube Q4, a third driving control circuit 41 for driving the third synchronous rectifying tube Q3, a second diode D2 and a fourth capacitor C4; the first synchronous rectifying tube Q1 and the fourth synchronous rectifying tube Q4 are synchronously conducted, and the second synchronous rectifying tube Q2 and the third synchronous rectifying tube Q3 are synchronously conducted;
The drain VD of the third synchronous rectifying tube Q3 is connected with the drain VD of the first synchronous rectifying tube Q1 and is used as an output positive end of the LED driving circuit;
the source VS of the fourth synchronous rectifier Q4, the reference end GND4 of the fourth driving control circuit 42, and the reference end GND2 of the second driving control circuit 14 are respectively connected to the source VS of the second synchronous rectifier Q2 and serve as the output ground GND of the LED driving circuit;
the source VS of the third synchronous rectifier Q3, the reference end GND3 of the third driving control circuit 41, one end of the fourth capacitor C4, and the drain VD of the fourth synchronous rectifier Q4 are respectively connected to the second end S2-2 of the second winding S2;
the power supply end VCC3 of the third driving control circuit 41 and the cathode of the second diode D2 are respectively connected to the other end of the fourth capacitor C4, and the fourth capacitor C4 is used for supplying power to the third driving control circuit 41; the anode of the second diode D2 and the power supply terminal VCC4 of the fourth driving control circuit 42 are respectively connected with the output terminal VCC of the auxiliary source circuit 121;
the ground terminal of the auxiliary source circuit 121 is the same as the reference terminals of the second driving control circuit 14 and the fourth driving control circuit 42, and is the negative output terminal GND of the LED driving circuit, so the auxiliary source circuit 121 can be directly used to supply power to the second driving control circuit 14 and the fourth driving control circuit 42, and when the fourth synchronous rectifier Q4 is turned on, the auxiliary source circuit 121 charges the fourth capacitor C4 through the second diode D2.
At this time, the secondary side rectifying circuit includes: the secondary side rectifying circuit is a full-bridge rectifying circuit, and the first synchronous rectifying tube Q1, the second synchronous rectifying tube Q2, the first driving control circuit 13, the second driving control circuit 14, the first capacitor C1, the first diode D1, the third synchronous rectifying tube Q3, the third driving control circuit 41, the second diode D2, the fourth capacitor C4, the fourth synchronous rectifying tube Q4 and the fourth driving control circuit 42 are all of the same.
As shown in fig. 4, since the source VS of the third synchronous rectifying tube Q3 is not the output ground GND of the LED driving circuit, the reference point of the driving signal of the third synchronous rectifying tube Q3 is not the output ground GND of the LED driving circuit, but the source VS of the third synchronous rectifying tube Q3, the auxiliary source circuit 121 with the ground connected to the output ground GND cannot supply power to the third driving control circuit 41, so the present invention stores energy for the fourth capacitor C4 through the second diode D2 by the auxiliary source circuit 121; in operation, the third driving control circuit 41 is supplied with power through the fourth capacitor C4; the specific working principle is as follows:
when the first end S2-1 of the second winding S2 is positive and the second end S2-2 is negative, the second winding S2, the first synchronous rectifier Q1, the load Cout and the fourth synchronous rectifier Q4 form a loop; at this time, the first capacitor C1 supplies power to the first driving control circuit 13, and since the fourth synchronous rectifying tube Q4 is turned on, the potential at one end of the fourth capacitor C4 is equal to the potential at the output ground GND of the LED driving circuit (ignoring the conduction voltage drop of the fourth synchronous rectifying tube Q4), so that the auxiliary source circuit 121 charges the fourth capacitor C4 through the second diode D2, and the fourth capacitor C4 stores energy.
When the first end S2-1 of the second winding S2 is negative and the second end S2-2 is positive, the second winding S2, the third synchronous rectifier Q3, the load Cout and the second synchronous rectifier Q2 form a loop; at this time, since the fourth synchronous rectifying tube Q4 is turned off and the third synchronous rectifying tube Q3 is turned on, the potential at one end of the fourth capacitor C4 is equal to the potential at the output positive end of the LED driving circuit, so that the potential at the positive end of the fourth capacitor C4, that is, the potential at the cathode of the second diode is vc4+vo (Vo is the output voltage of the LED driving circuit, that is, the voltage on Cout, and Vc4 is the stored voltage on the fourth capacitor C4), and since the voltage Vo at the output positive end of the LED driving circuit is generally higher than the voltage Vcc at the output end of the auxiliary source circuit 121, the voltage at the cathode of the second diode D4 is greater than the voltage at the anode of the second diode D4, the second diode D2 is turned off reversely, and the fourth capacitor C4 is powered by the third driving control circuit 41, so that the third driving control circuit 41 normally outputs the driving signal. And in this operating state, the auxiliary source circuit 121 charges the first capacitor C1 through the first diode D1, and the first capacitor C1 stores energy.
As can be seen, the power supply end VCC3 of the third driving control circuit 41 is connected to one end of the fourth capacitor C4, and the reference end GND3 of the third driving control circuit 41 is connected to the other end of the fourth capacitor C4, so that the fourth capacitor C4 supplies power to the third driving control circuit 41.
Further, since the ground terminal of the auxiliary source circuit 121 is connected to the output ground terminal GND of the LED driving circuit, as shown in fig. 4, the output ground terminal GND of the LED driving circuit is the source VS of the fourth synchronous rectifying tube Q4, the source VS of the fourth synchronous rectifying tube Q4 is connected to the output ground terminal GND of the LED driving circuit, and the reference terminal GND4 of the fourth driving control circuit 42 is connected to the output ground terminal GND of the LED driving circuit, the power supply source of the fourth driving control circuit 42 may be the auxiliary source circuit 121, so that the power supply terminal VCC4 of the fourth driving control circuit 42 is connected to the output terminal VCC of the auxiliary source circuit 121 for obtaining the power supply. It should be noted that, the auxiliary source circuit 121 may also supply power to other circuit units in the LED driving circuit, such as a loop control unit.
Through the above description, in the embodiment of the invention, the LED driving circuit uses the synchronous rectifying tube as the rectifying component to replace the diode, so that the problem of large on-state loss caused by the diode as the rectifying component is solved, and the power supply problem of all driving control circuits is solved.
Based on the above embodiments, referring to fig. 5, fig. 5 is a schematic structural diagram of a driving control circuit according to an embodiment of the present invention. Wherein the first drive control circuit 13 includes: a first processing unit 52 and a first detecting unit 51; the first detecting unit 51 is connected in parallel with the first synchronous rectifying tube Q1, and is configured to detect a source-drain voltage Vsd of the first synchronous rectifying tube Q1, and send a detection result to the first processing unit 52; the first processing unit 52 is configured to generate a driving signal according to a detection result of the first detecting unit 51; and sends the driving signal to the first synchronous rectifying tube Q1, specifically to the gate VG of the first synchronous rectifying tube Q1;
the second drive control circuit 14 includes: the second processing unit and the second detection unit; the second detection unit is connected in parallel with the second synchronous rectifying tube Q2 and is used for detecting the source-drain voltage Vsd of the second synchronous rectifying tube Q2 and sending the detection result to the second processing unit; the second processing unit is used for generating a driving signal according to the detection result of the second synchronous rectifying tube Q2; the driving signal is sent to the second synchronous rectifying tube Q2, specifically, to the grid VG of the second synchronous rectifying tube Q2;
The third drive control circuit 41 includes: a third processing unit and a third detecting unit; the third detection unit is connected in parallel with the third synchronous rectifying tube Q3, and is configured to detect a source-drain voltage Vsd of the third synchronous rectifying tube Q3, and send a detection result to the third processing unit; the third processing unit is configured to generate a driving signal according to a detection result of the third synchronous rectifying tube Q3, and send the driving signal to the third synchronous rectifying tube Q3, specifically, to a gate VG of the third synchronous rectifying tube Q3;
the fourth drive control circuit 42 includes: a fourth processing unit and a fourth detecting unit; the fourth detection unit is connected in parallel with the fourth synchronous rectifying tube Q4, and is configured to detect a source-drain voltage Vsd of the fourth synchronous rectifying tube Q4, and send a detection result to the fourth processing unit; the fourth processing unit is configured to generate a driving signal according to a detection result of the fourth synchronous rectifying tube Q4, and send the driving signal to the fourth synchronous rectifying tube Q4, specifically, to the gate VG of the fourth synchronous rectifying tube Q3.
In the following, taking the first synchronous rectifier Q1 as an example, as shown in fig. 5, when the first detecting unit 51 detects that the source-drain voltage Vsd of the first synchronous rectifier Q1 is a forward conduction voltage (i.e., the body diode a of the first synchronous rectifier Q1 is forward conducted), the first processing unit 52 generates a first on driving signal to turn on the first synchronous rectifier Q1, and when the first detecting unit 51 detects that the forward voltage drop of the source-drain voltage Vsd of the first synchronous rectifier Q2 is zero (i.e., no current flows through the first synchronous rectifier Q1) or the source-drain voltage Vsd is a reverse voltage drop (i.e., the drain VD of the first synchronous rectifier Q1 is higher than the source VS voltage), the first processing unit 52 generates a first off driving signal.
When the first synchronous rectifier Q1 is turned on, the current I in the circuit flows from the source VS to the drain VD through the on-resistance of the first synchronous rectifier Q1 and does not pass through the body diode a, so that no loss is generated in the body diode a. The on-resistance is not shown in fig. 5.
Since the current I will pass through the on-resistance Rdson, the loss qr=i due to the on-resistance 2 * Rdson, if current I passes through body diode a, loss qd=i×vd generated by body diode a. However, since the on-resistance Rdson of the first synchronous rectifier Q1 is very small, vd of the body diode a is generally fixed to 0.7V. Therefore, qr is much smaller than Qd, which illustrates that using the first synchronous rectifier as Q1 as the rectifier device can improve circuit efficiency.
Similarly, when the second detection unit detects that the source-drain voltage Vsd of the second synchronous rectifier Q2 is a forward conduction voltage, the second processing unit generates a second conduction driving signal; when the second detection unit detects that the forward voltage drop of the source-drain voltage Vsd of the second synchronous rectifier tube Q2 is zero or is a reverse voltage drop, the second processing unit generates a second turn-off driving signal;
When the third detection unit detects that the source-drain voltage Vsd of the third synchronous rectifier Q3 is a forward conduction voltage, the third processing unit generates a third conduction driving signal; when the third detection unit detects that the forward voltage drop of the source-drain voltage Vsd of the third synchronous rectifier tube Q3 is zero or a reverse voltage drop, the third processing unit generates a third turn-off driving signal;
when the fourth detection unit detects that the source-drain voltage Vsd of the fourth synchronous rectifier Q4 is a forward conduction voltage, the fourth processing unit generates a fourth conduction driving signal; when the fourth detection unit detects that the forward voltage drop of the source-drain voltage Vsd of the fourth synchronous rectifier Q4 is zero or a reverse voltage drop, the fourth processing unit generates a fourth off driving signal.
Optionally, in an embodiment of the present invention, referring to fig. 6, fig. 6 is a schematic structural diagram of a synchronous rectifier according to an embodiment of the present invention. The first synchronous rectifier Q1 and the first driving control circuit 13 are integrated in a first synchronous rectifier TQ1, that is, the first synchronous rectifier TQ1, the first processing unit 52 and the first detecting unit 51 are integrated in the first synchronous rectifier TQ 1; the source VS of the first synchronous rectifier Q1 is connected to the reference terminal GND1 of the first driving control circuit 13.
The source S of the first synchronous rectifier TQ1 is the source VS of the first synchronous rectifier Q1; the drain D of the first synchronous rectifier TQ1 is the drain VD of the first synchronous rectifier Q1, and the power supply end VCC1 of the first synchronous rectifier TQ1 is the power supply end VCC1 of the first driving control circuit 13.
That is, the first synchronous rectifier Q1 and the first driving control circuit 13 are used as an integrated circuit, which is defined as the first synchronous rectifier TQ1, and the first synchronous rectifier TQ1 includes: the source S, drain D and supply terminal VCC1 are referred to as a three-terminal synchronous rectifier.
Similarly, the second synchronous rectifying tube Q2 and the second driving control circuit 14 are integrated in a second synchronous rectifier TQ2, that is, the second synchronous rectifying tube Q2, the second processing unit and the second detecting unit are integrated in the second synchronous rectifier TQ 2; the source VS of the second synchronous rectifier Q2 is connected to the reference terminal GND2 of the second driving control circuit 14.
The source S of the second synchronous rectifier TQ2 is the source VS of the second synchronous rectifier Q2; the drain D of the second synchronous rectifier TQ2 is the drain VD of the second synchronous rectifier Q2, and the power supply end VCC2 of the second synchronous rectifier TQ2 is the power supply end VCC2 of the second driving control circuit 14.
That is, the second synchronous rectifier Q2 and the second driving control circuit 14 are used as an integrated circuit, which is defined as the second synchronous rectifier TQ2, and the second synchronous rectifier TQ2 includes: the source S, drain D and supply terminal VCC2 are referred to as a three-terminal synchronous rectifier.
The third synchronous rectifying tube Q3 and the third driving control circuit 41 are integrated in a third synchronous rectifier TQ3, that is, the third synchronous rectifying tube Q3, the third processing unit and the third detecting unit are integrated in the third synchronous rectifier TQ 3; the source VS of the third synchronous rectifier Q3 is connected to the reference terminal GND3 of the third driving control circuit 41.
The source S of the third synchronous rectifier TQ3 is the source VS of the third synchronous rectifier Q3; the drain D of the third synchronous rectifier TQ3 is the drain VD of the third synchronous rectifier Q3, and the power supply end VCC3 of the third synchronous rectifier TQ3 is the power supply end VCC3 of the third driving control circuit 41.
That is, the third synchronous rectifier Q3 and the third driving control circuit 41 are used as an integrated circuit, which is defined as the third synchronous rectifier TQ3, and the third synchronous rectifier TQ3 includes: the source S, drain D and supply terminal VCC3 are referred to as a three-terminal synchronous rectifier.
The fourth synchronous rectifying tube Q4 and the fourth driving control circuit 42 are integrated in a fourth synchronous rectifier TQ4, that is, the fourth synchronous rectifying tube Q4, the fourth processing unit and the fourth detecting unit are integrated in the fourth synchronous rectifier TQ 4; the source VS of the fourth synchronous rectifier Q4 is connected to the reference terminal GND4 of the fourth driving control circuit 42.
The source S of the fourth synchronous rectifier TQ4 is the source VS of the fourth synchronous rectifier Q4; the drain D of the fourth synchronous rectifier TQ4 is the drain VD of the fourth synchronous rectifier Q4, and the power supply end VCC4 of the fourth synchronous rectifier TQ4 is the power supply end VCC4 of the fourth driving control circuit 42.
That is, the fourth synchronous rectifier Q4 and the fourth driving control circuit 42 are used as an integrated circuit, which is defined as the fourth synchronous rectifier TQ4, and the fourth synchronous rectifier TQ4 includes: the source S, drain D and supply terminal VCC4 are referred to as a three-terminal synchronous rectifier.
Referring to fig. 7, fig. 7 is a schematic structural diagram of another LED driving circuit according to an embodiment of the present invention. The source electrode S of the first synchronous rectifier TQ1 is connected with one end of the first capacitor C1; the power supply end VCC1 of the first synchronous rectifier TQ1 is connected with the other end of the first capacitor C1 and is used for obtaining a power supply; one end of the first capacitor C1 connected to the power supply end VCC1 of the first synchronous rectifier TQ1 is connected to the output end VCC of the auxiliary source circuit 121 through a first diode D1, and the anode of the first diode is connected to the output end VCC of the auxiliary source circuit 121, and the cathode is connected to the power supply end VCC1 of the first synchronous rectifier TQ 1.
The source S of the second synchronous rectifier TQ2 is connected to the output ground GND of the LED driving circuit, the power supply VCC2 of the second synchronous rectifier TQ2 is connected to the output VCC of the auxiliary source circuit 121, and the auxiliary source circuit 121 is configured to supply power to the second synchronous rectifier TQ 2.
Referring to fig. 8, fig. 8 is a schematic structural diagram of another LED driving circuit according to an embodiment of the present invention, where a source S of the third synchronous rectifier TQ3 is connected to one end of the fourth capacitor C4; the power supply end VCC3 of the third synchronous rectifier TQ3 is connected with the other end of the fourth capacitor C4 and is used for acquiring a power supply; one end of the fourth capacitor C4 connected to the power supply end VCC3 of the third synchronous rectifier TQ3 is connected to the output end VCC of the auxiliary source circuit 121 through a second diode D2, and the anode of the second diode is connected to the output end VCC of the auxiliary source circuit 121, and the cathode is connected to the power supply end VCC3 of the third synchronous rectifier TQ 3.
The source S of the fourth synchronous rectifier TQ4 is connected to the output ground GND of the LED driving circuit, the power supply VCC4 of the fourth synchronous rectifier TQ4 is connected to the output VCC of the auxiliary source circuit 121, and the auxiliary source circuit 121 is configured to supply power to the fourth synchronous rectifier TQ 4.
It should be noted that, in this application, the term "power … …", where the first capacitor "powers" the first driving control circuit, or the first capacitor "powers" the first synchronous rectifier, or the fourth capacitor "powers" the third driving control circuit, or the fourth capacitor "powers" the third synchronous rectifier, or the auxiliary source circuit "powers" the second driving control circuit, etc., refers to: a power supply for supplying direct current and assisting the work of the device.
As can be seen from the above description, the LED driving circuit provided by the present invention solves the problem of large on-state loss caused by the diode as the rectifying component by providing the synchronous rectifying tube instead of the diode of the rectifying component in the prior art, and the corresponding driving control circuit is used for conducting the corresponding synchronous rectifying tube to enable current to flow from the source to the drain, and not pass through the body diode in the synchronous rectifying tube, so that loss is not generated on the body diode.
Meanwhile, the first capacitor supplies power to the first drive control circuit through energy conversion of the first capacitor and the first diode, the fourth capacitor supplies power to the third drive control circuit through energy conversion of the fourth capacitor and the second diode, and the auxiliary source circuit supplies power to the second drive control circuit and the fourth drive control circuit, so that the power supply problem of different drive control circuits is solved.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. An LED driving circuit, comprising: a high-frequency pulse current source, an isolation transformer and a secondary side rectifying circuit;
wherein, the isolation transformer includes: a first winding and a second winding; the high-frequency pulse current source is connected with the first winding;
the secondary side rectifying circuit includes: a first load circuit and a second load circuit which alternately operate; the first load loop comprises a first synchronous rectifier tube, and the second load loop comprises a second synchronous rectifier tube; the first synchronous rectifying tube and the second synchronous rectifying tube are alternately conducted; the secondary rectifying circuit further comprises a first driving control circuit for driving the first synchronous rectifying tube, a second driving control circuit for driving the second synchronous rectifying tube, a first capacitor and a first diode;
The source electrode of the first synchronous rectifying tube is connected with the first end of the second winding and is used as the input end of the first load loop; the drain electrode of the first synchronous rectifying tube is an output positive end; an output of the first load loop is connected to a second end of the second winding;
the input end of the second load loop is connected with the second end of the second winding, and the drain electrode of the second synchronous rectifying tube is connected with the first end of the second winding and used as the output end of the second load loop; the source electrode of the second synchronous rectifying tube is an output ground end;
the reference end of the first drive control circuit is connected with the source electrode of the first synchronous rectifying tube;
the reference end of the second drive control circuit is connected with the source electrode of the second synchronous rectifying tube; the power supply end of the second drive control circuit is connected with a direct current power supply, and the grounding end of the direct current power supply is a reference end of the second drive control circuit;
the anode of the first diode is connected with the direct current power supply, and the cathode of the first diode is connected with the power supply end of the first drive control circuit; one end of the first capacitor is connected with the power supply end of the first drive control circuit, and the other end of the first capacitor is connected with the reference end of the first drive control circuit.
2. The LED driving circuit of claim 1, wherein the first driving control circuit comprises: the first processing unit and the first detection unit; the first detection unit is connected with the first synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the first synchronous rectifying tube and sending a detection result to the first processing unit;
the first processing unit is used for generating a driving signal according to the detection result; and transmitting the driving signal to the gate of the first synchronous rectifier tube;
the second drive control circuit includes: the second processing unit and the second detection unit;
the second detection unit is connected with the second synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the second synchronous rectifying tube and sending a detection result to the second processing unit;
the second processing unit is used for generating a driving signal according to the detection result; and transmitting the driving signal to the grid electrode of the second synchronous rectifying tube.
3. The LED driving circuit according to claim 2, wherein the first processing unit generates a first on driving signal when the first detecting unit detects that the source-drain voltage of the first synchronous rectifier tube is a forward on voltage; when the first detection unit detects that the source-drain voltage forward voltage drop of the first synchronous rectifying tube is zero or is reverse voltage drop, the first processing unit generates a first turn-off driving signal;
When the second detection unit detects that the source-drain voltage of the second synchronous rectifier tube is forward conduction voltage, the second processing unit generates a second conduction driving signal; and when the second detection unit detects that the source-drain voltage forward voltage drop of the second synchronous rectifying tube is zero or the reverse voltage drop, the second processing unit generates a second turn-off driving signal.
4. The LED driving circuit of claim 3, wherein the first load loop further comprises a third capacitor and the second load loop further comprises a second capacitor;
in the first load loop, one end of the third capacitor is an output end of the first load loop and is connected with a second end of the second winding; the other end of the third capacitor is connected with the output ground end;
in the second load loop, one end of the second capacitor is an input end of the second load loop and is connected with a second end of the second winding; the other end of the second capacitor is connected with the output positive end.
5. The LED driving circuit of claim 3, wherein the first load loop further comprises a fourth synchronous rectifier, and the second load loop further comprises a third synchronous rectifier;
The secondary side rectifying circuit further comprises a fourth driving control circuit for driving the fourth synchronous rectifying tube, a third driving control circuit for driving the third synchronous rectifying tube, a second diode and a fourth capacitor; the first synchronous rectifying tube and the fourth synchronous rectifying tube are synchronously conducted, and the second synchronous rectifying tube and the third synchronous rectifying tube are synchronously conducted;
in the first load loop, the drain electrode of the fourth synchronous rectifying tube is an output end of the first load loop and is connected with the second end of the second winding, and the source electrode of the fourth synchronous rectifying tube is connected with the output ground end;
in the second load loop, the source of the third synchronous rectifier tube is the input end of the second load loop and is connected with the second end of the second winding, and the drain electrode of the third synchronous rectifier tube is connected with the output positive end;
the reference end of the third driving control circuit is connected with the source electrode of the third synchronous rectifying tube; the output end of the third driving control circuit is connected with the grid electrode of the third synchronous rectifying tube; the anode of the second diode is connected with the direct current power supply, and the cathode of the second diode is connected with the power supply end of the third drive control circuit; one end of the fourth capacitor is connected with the power supply end of the third drive control circuit; the other end of the fourth capacitor is connected with the reference end of the third driving control circuit;
The reference end of the fourth driving control circuit is connected with the source electrode of the fourth synchronous rectifying tube; the output end of the fourth driving control circuit is connected with the grid electrode of the fourth synchronous rectifying tube; and the power supply end of the fourth drive control circuit is connected with the direct current power supply.
6. The LED driving circuit of claim 5, wherein the third driving control circuit comprises: a third processing unit and a third detecting unit;
the third detection unit is connected with the third synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the third synchronous rectifying tube and sending a detection result to the third processing unit;
the third processing unit is used for generating a driving signal according to the detection result and sending the driving signal to the grid electrode of the third synchronous rectifying tube;
the fourth drive control circuit includes: a fourth processing unit and a fourth detecting unit;
the fourth detection unit is connected with the fourth synchronous rectifying tube in parallel and is used for detecting the source-drain voltage of the fourth synchronous rectifying tube and sending a detection result to the fourth processing unit;
the fourth processing unit is used for generating a driving signal according to the detection result and sending the driving signal to the grid electrode of the fourth synchronous rectifying tube;
When the third detection unit detects that the source-drain voltage of the third synchronous rectifier tube is forward conduction voltage, the third processing unit generates a third conduction driving signal; when the third detection unit detects that the source-drain voltage forward voltage drop of the third synchronous rectifying tube is zero or is reverse voltage drop, the third processing unit generates a third turn-off driving signal;
when the fourth detection unit detects that the source-drain voltage of the fourth synchronous rectifier tube is forward conduction voltage, the fourth processing unit generates a fourth conduction driving signal; and when the fourth detection unit detects that the forward voltage drop of the source-drain voltage of the fourth synchronous rectifying tube is zero or the reverse voltage drop, the fourth processing unit generates a fourth turn-off driving signal.
7. The LED driving circuit of claim 1, wherein the first synchronous rectifier tube is integrated with the first drive control circuit in a first synchronous rectifier;
the first synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the first synchronous rectifier is the source electrode of the first synchronous rectifier; the drain electrode of the first synchronous rectifier is the drain electrode of the first synchronous rectifier, and the power supply end of the first synchronous rectifier is the power supply end of the first drive control circuit;
Or the second synchronous rectifier tube and the second driving control circuit are integrated in a second synchronous rectifier;
the second synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the second synchronous rectifier is the source electrode of the second synchronous rectifier; the drain electrode of the second synchronous rectifier is the drain electrode of the second synchronous rectifier, and the power supply end of the second synchronous rectifier is the power supply end of the second drive control circuit.
8. The LED driving circuit of claim 5, wherein the third synchronous rectifier tube is integrated with the third drive control circuit in a third synchronous rectifier;
the third synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the third synchronous rectifier is the source electrode of the third synchronous rectifier; the drain electrode of the third synchronous rectifier is the drain electrode of the third synchronous rectifier, and the power supply end of the third synchronous rectifier is the power supply end of the third drive control circuit;
or the fourth synchronous rectifier tube and the fourth driving control circuit are integrated in a fourth synchronous rectifier;
the fourth synchronous rectifier includes: a source electrode, a drain electrode and a power supply end; the source electrode of the fourth synchronous rectifier is the source electrode of the fourth synchronous rectifier; the drain electrode of the fourth synchronous rectifier is the drain electrode of the fourth synchronous rectifier, and the power supply end of the fourth synchronous rectifier is the power supply end of the fourth drive control circuit.
9. The LED driving circuit according to any one of claims 1 to 8, wherein the dc power supply is an auxiliary source circuit of the LED driving circuit, the isolation transformer further comprising a third winding, and an input terminal of the auxiliary source circuit is connected to the third winding.
10. The LED driving circuit according to claim 9, wherein the high frequency pulse current source is an LLC circuit topology or an LCC circuit topology.
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| CN206759768U (en) * | 2017-03-01 | 2017-12-15 | 浙江英飞特光电有限公司 | A kind of LED drive circuit |
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| JP5335808B2 (en) * | 2007-12-07 | 2013-11-06 | コーニンクレッカ フィリップス エヌ ヴェ | LED lamp power management system and method |
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| CN1985427A (en) * | 2004-09-30 | 2007-06-20 | 三垦电气株式会社 | DC power supply apparatus |
| JP2009142001A (en) * | 2007-12-04 | 2009-06-25 | Yokogawa Electric Corp | Synchronous rectification driving circuit |
| CN102412709A (en) * | 2010-09-17 | 2012-04-11 | 东芝照明技术株式会社 | Switching power supply device and adjustable power supply system including the same |
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