CN217335972U

CN217335972U - LED drive circuit

Info

Publication number: CN217335972U
Application number: CN202220339435.9U
Authority: CN
Inventors: 周俊; 孙运
Original assignee: On Bright Electronics Shanghai Co Ltd
Current assignee: On Bright Electronics Shanghai Co Ltd
Priority date: 2022-02-18
Filing date: 2022-02-18
Publication date: 2022-08-30
Anticipated expiration: 2032-02-18
Also published as: TWM635228U

Abstract

There is provided an LED driver circuit comprising a rectifying or Power Factor Correction (PFC) circuit module, an asymmetric half-bridge driver circuit module, a control circuit module, and an output filter circuit module, wherein: the first terminal and the second terminal of the rectification or PFC circuit module are used for connecting two ends of an alternating current power supply, and the third terminal of the rectification or PFC circuit module is connected to the first terminal of the asymmetric half-bridge driving circuit module and the first terminal and the fourth terminal of the control circuit module and grounded; the second, third, fourth, fifth, sixth and seventh terminals of the asymmetric half-bridge driving circuit module are respectively connected to the second, third, fourth, fifth, sixth and seventh terminals of the control circuit module, the eighth and ninth terminals are respectively connected to the first and second terminals of the output filter circuit module, and the tenth terminal is grounded; and the third and fourth terminals of the output filter circuit module are used for connecting two ends of the LED load.

Description

LED drive circuit

Technical Field

The utility model relates to a circuit field especially relates to a LED drive circuit.

Background

With the continuous development of electronic technology, the volume of Light Emitting Diode (LED) lamps is smaller and smaller, and the market demands high power density and miniaturization for LED driving circuits. In a conventional flyback LED driving circuit, in a high frequency mode, as an operating frequency increases, a loss of a power switching tube increases, and a temperature rise of a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) used to implement the power switching tube is high, so that system efficiency is deteriorated. In order to improve the system efficiency of the flyback LED driving circuit, a MOSFET with lower on-resistance or a GaN field effect transistor (GaN FET) needs to be selected as the power switch transistor, which increases the system cost and is not favorable for product upgrade.

SUMMERY OF THE UTILITY MODEL

According to the utility model discloses LED drive circuit, including rectification or Power Factor Correction (PFC) circuit module, asymmetric half-bridge drive circuit module, control circuit module and output filter circuit module, wherein: the first terminal and the second terminal of the rectifying or PFC circuit module are used for connecting two ends of an alternating current power supply, and the third terminal of the rectifying or PFC circuit module is connected to the first terminal of the asymmetric half-bridge driving circuit module and the first terminal and the fourth terminal of the control circuit module and grounded; the second, third, fourth, fifth, sixth and seventh terminals of the asymmetric half-bridge driving circuit module are respectively connected to the second, third, fourth, fifth, sixth and seventh terminals of the control circuit module, the eighth and ninth terminals are respectively connected to the first and second terminals of the output filter circuit module, and the tenth terminal is grounded; and the third and fourth terminals of the output filter circuit module are used for connecting two ends of the LED load.

According to the utility model discloses LED drive circuit has simple structure, safe efficient characteristics to can effectively promote system efficiency, reduce system cost.

Drawings

The invention may be better understood from the following description of particular embodiments thereof taken in conjunction with the accompanying drawings, in which:

fig. 1 shows an example circuit diagram of an LED drive circuit according to an embodiment of the present invention;

fig. 2 shows a pin layout and a schematic block diagram of internal functional units of the control chip U1 shown in fig. 1.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The present invention is in no way limited to any specific configuration set forth below, but covers any modification, replacement or improvement of elements and components without departing from the spirit of the present invention. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present invention. Note that, the term "a and B are connected" as used herein may mean "a and B are directly connected" or "a and B are indirectly connected via one or more other elements".

For the LED driving circuit, the half-bridge resonant framework can realize zero-voltage starting of the power switching tube by utilizing resonant current, so that the system efficiency is improved; the flyback architecture is suitable for wide voltage range application; the Bipolar Junction Transistor (BJT) and the MOSFET are used as power switching tubes and have the advantage of low cost, the combination of the Bipolar Junction Transistor (BJT) and the MOSFET can be suitable for wide voltage range application, and can control the zero voltage starting of the power switching tubes, so that the low cost and the high efficiency of the whole circuit system can be realized.

Based on the above consideration, provided according to the utility model discloses LED drive circuit has simple structure, safe efficient characteristics to can effectively promote system efficiency, reduce system cost.

Fig. 1 shows an example circuit diagram of an LED driving circuit 100 according to an embodiment of the present invention. As shown in fig. 1, the LED driving circuit 100 is formed on the basis of a resonant conversion circuit and includes a rectifying or Power Factor Correction (PFC) circuit module 102, an asymmetric half-bridge driving circuit module 104, a control circuit module 106, and an output filter circuit module 108, wherein: the first and second terminals of the rectifying or PFC circuit module 102 are used to connect two ends of an ac power source, and the third terminal is connected to the first terminal of the asymmetric half-bridge driving circuit module 104 and the first and fourth terminals of the control circuit module 106; the second, third, fourth, fifth, sixth, and seventh terminals of the asymmetric half-bridge driver circuit module 104 are connected to the second, third, fourth, fifth, sixth, and seventh terminals of the control circuit module 106, respectively, the eighth and ninth terminals are connected to the first and second terminals of the output filter circuit module 108, respectively, and the tenth terminal is grounded; the third and fourth terminals of the output filter circuit module 108 are used for connecting two ends of the LED load.

As shown in fig. 1, in some embodiments, the rectifying or PFC circuit module 102 includes a rectifying or PFC circuit unit and a filter capacitor C1, wherein the rectifying or PFC circuit unit may be implemented as a rectifying filter circuit, a passive PFC boost circuit, or an active PFC boost circuit.

As shown in fig. 1, in some embodiments, the asymmetric half-bridge driver circuit module 104 includes a driving transformer T1, a power transformer T2, a Bipolar Junction Transistor (BJT) Q1, a MOSFET M1, capacitors C2 and C3, a resistor R1, and diodes D1 and D2.

As shown in fig. 1, in some embodiments, the control circuit module 106 includes a control chip U1, a capacitor C4, resistors R2, R3, R4, and R5, and a diode D3.

As shown in fig. 1, in some embodiments, the output filter circuit module 108 includes an output rectifying diode D4, a filter capacitor C5, and a resistor R6. The output filter circuit module 108 may further include a pi filter circuit or a common mode filter circuit for different output ripple requirements.

Fig. 2 shows a pin layout and a schematic block diagram of internal functional units of the control chip U1 shown in fig. 1. As shown in fig. 2, in some embodiments, the control chip U1 includes a first driving output pin TX1, a second driving output pin TX2, a dead time setting pin SDT, a chip ground reference pin GND, a zero voltage turn-on detection pin RV, a voltage feedback input pin DEM, a chip power supply input pin VDD, and a current sampling input pin CS, wherein:

the first driving output pin TX1 outputs a first driving signal to the driving transformer T1 to control the driving transformer T1 to drive the turn-on and turn-off of a Bipolar Junction Transistor (BJT) Q1;

the second driving output pin TX2 directly outputs a second driving signal to the MOSFET M1 to drive the MOSFET M1 to turn on and off;

the dead time setting pin SDT is grounded via a resistor R5, and is used for setting a dead time between a first driving signal output by the first driving output pin TX1 and a second driving signal output by the second driving output pin TX 2;

the chip reference ground pin GND is grounded and is used for providing a chip reference ground for the internal circuit of the control chip U1;

the zero voltage turn-on detection pin RV is connected to a connection node between a Bipolar Junction Transistor (BJT) Q1 and a MOSFET M1 via a capacitor C2 for achieving zero voltage turn-on of the Bipolar Junction Transistor (BJT) Q1 and the MOSFET M1;

the voltage feedback input pin DEM is connected to a connection node between the resistors R3 and R4, and is used for detecting the voltage of the output voltage of the LED driving circuit 100 mapped to the primary winding of the power transformer T2 through a voltage division network formed by the resistors R3 and R4 and detecting a demagnetization representation signal representing the end of demagnetization of the primary winding of the power transformer T2;

the chip power supply input pin VDD is grounded through a capacitor C4, connected to the auxiliary winding end of the power transformer T2 through a diode D3, and connected to the positive end of a filter capacitor C1 through a resistor R2;

the current sampling input pin CS is connected to one end of a resistor R1 for detecting the current flowing through the primary winding of the power transformer T2.

As shown in fig. 2, in some embodiments, the control chip U1 includes a zero voltage turn-on detection unit 1062, a demagnetization detection unit 1064, a dead time control unit 1066, a constant current control unit 1068, a low dropout linear regulator unit 1070, a first driver unit 1072, a second driver unit 1074, and a logic control unit 1076, wherein:

a first end of the zero-voltage-on detection unit 1062 is connected to the zero-voltage-on detection pin RV, and a second end is connected to the logic control unit 1076;

a first end of the demagnetization detection unit 1064 is connected to the voltage feedback input pin DEM, and a second end is connected to the logic control unit 1076;

dead time control unit 1066 has a first end connected to dead time setting pin SDT and a second end connected to logic control unit 1076;

a first end of the constant current control unit 1068 is connected to the current sampling input pin CS, and second and third ends are connected to the logic control unit 1076;

the low dropout linear regulator unit 1070 is connected to the chip power supply input pin VDD;

the first driver unit 1072 has a first terminal connected to the first driving output pin TX1 and a second terminal connected to the logic control unit 1076;

the second driver unit 1074 has a first terminal connected to the second driving output pin TX2 and a second terminal connected to the logic control unit 1076.

In the LED driving circuit according to the embodiment of the present invention, an NPN-type Bipolar Junction Transistor (BJT) may be adopted as an upper power switch tube in the asymmetric half-bridge driving circuit module 104 and a power MOSFET may be adopted as a lower power switch tube in the asymmetric half-bridge driving circuit module 104, wherein the power MOSFET may be an N-type MOSFET, a vertical channel double diffusion MOSFET (vd MOSFET), a low internal resistance MOSFET (cool MOSFET), a super junction MOSFET (sj MOSFET), or a GaN MOSFET.

In the LED driving circuit according to the embodiment of the present invention, a self-oscillation converter using a Bipolar Junction Transistor (BJT) and a MOSFET as a power switching tube is realized, and zero-voltage turn-on of the Bipolar Junction Transistor (BJT) and the MOSFET is realized.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. An LED driver circuit comprising a rectifying or Power Factor Correction (PFC) circuit module, an asymmetric half-bridge driver circuit module, a control circuit module, and an output filter circuit module, wherein:

the first terminal and the second terminal of the rectifying or PFC circuit module are used for connecting two ends of an alternating current power supply, and the third terminal of the rectifying or PFC circuit module is connected to the first terminal of the asymmetric half-bridge driving circuit module and the first terminal and the fourth terminal of the control circuit module and grounded;

the second, third, fourth, fifth, sixth and seventh terminals of the asymmetric half-bridge driving circuit module are respectively connected to the second, third, fourth, fifth, sixth and seventh terminals of the control circuit module, the eighth and ninth terminals are respectively connected to the first and second terminals of the output filter circuit module, and the tenth terminal is grounded;

and the third terminal and the fourth terminal of the output filter circuit module are used for connecting two ends of an LED load.

2. The LED driving circuit according to claim 1, wherein the rectifying or PFC circuit module comprises a rectifying or PFC circuit unit and a filter capacitor.

3. The LED driving circuit according to claim 2, wherein the rectifying or PFC circuit unit is implemented as a rectifying filter circuit, a passive PFC boost circuit, or an active PFC boost circuit.

4. The LED driver circuit of claim 1, wherein the asymmetric half-bridge driver circuit module comprises a drive transformer, a power transformer, a Bipolar Junction Transistor (BJT), and a metal-oxide-semiconductor field-effect transistor (MOSFET).

5. The LED driving circuit according to claim 1, wherein the control circuit module comprises a control chip.

6. The LED driving circuit of claim 1, wherein the output filter circuit module comprises an output rectifier diode, a filter capacitor, and a resistor.

7. The LED driving circuit of claim 6, wherein the output filter circuit module further comprises a pi-type filter circuit or a common-mode filter circuit.

8. The LED driving circuit according to claim 5, wherein the control chip comprises one or more of the following pins:

a first driving output pin, configured to output a first driving signal, where the first driving signal drives a Bipolar Junction Transistor (BJT) in the asymmetric half-bridge driving circuit module to turn on and off;

a second driving output pin, configured to output a second driving signal, where the second driving signal drives a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) in the asymmetric half-bridge driving circuit module to turn on and off;

a dead time setting pin for setting a dead time between the first driving signal and the second driving signal;

the chip reference ground pin is used for providing a chip reference ground for the internal circuit of the control chip;

a zero voltage turn-on detection pin for realizing zero voltage turn-on of a Bipolar Junction Transistor (BJT) and a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) in the asymmetric half-bridge driving circuit module;

a voltage feedback input pin, configured to detect that an output voltage of the LED driving circuit is mapped to a voltage of a primary winding of a power transformer in the asymmetric half-bridge driving circuit module, and detect a demagnetization characterization signal that characterizes an end of demagnetization of the primary winding of the power transformer;

a chip power supply input pin for receiving power supply from the outside; and

and the current sampling input pin is used for detecting the current flowing through the primary winding of the power transformer.

9. The LED driving circuit according to claim 8, wherein the control chip further comprises a zero voltage turn-on detection unit, a demagnetization detection unit, a dead time control unit, a constant current control unit, a low dropout regulator unit, a first driver unit, a second driver unit, and a logic control unit, wherein:

the first end of the zero voltage starting detection unit is connected to the zero voltage starting detection pin, and the second end of the zero voltage starting detection unit is connected to the logic control unit;

the first end of the demagnetization detection unit is connected to the voltage feedback input pin, and the second end of the demagnetization detection unit is connected to the logic control unit;

the first end of the dead time control unit is connected to the dead time setting pin, and the second end of the dead time control unit is connected to the logic control unit;

the first end of the constant current control unit is connected to the current sampling input pin, and the second end and the third end of the constant current control unit are connected to the logic control unit;

the low dropout linear regulator unit is connected to the chip power supply input pin;

the first end of the first driver unit is connected to the first driving output pin, and the second end of the first driver unit is connected to the logic control unit;

the first end of the second driver unit is connected to the second drive output pin, and the second end of the second driver unit is connected to the logic control unit.