TWM606353U - LED driving circuit - Google Patents

Abstract

This creation provides an LED (Light Emitting Diode) drive circuit, including an AC input rectification filter circuit, a sensing control circuit, a power conversion transmission transformer, and an output rectification filter circuit. The sensing control circuit includes: a control chip; a dimming signal acquisition circuit, the first and second ends of which are respectively connected to the second and first output ends of the AC input rectifier filter circuit, and the third end is connected to the control chip; the start circuit , Its first end is connected to the third output end of the AC input rectifier filter circuit and the first end of the power conversion transmission transformer, its second end is grounded, and its third end is connected to the control chip; the power MOS field effect transistor, which The drain is connected to the second end of the power conversion and transmission transformer, the gate is connected to the control chip, and the source is connected to the control chip; and the output information sampling circuit, the first end of which is connected to the second end of the power conversion and transmission transformer, Its second end is connected to the control chip.

Description

LED drive circuit

This creation relates to the field of circuits, and more specifically, to an LED drive circuit.

Light Emitting Diode (LED) is a semiconductor device that converts electrical energy into light energy. The core part of the LED is the PN junction, and the luminous flux of the LED is proportional to the current flowing through the LED. Compared with traditional lighting fixtures such as incandescent lamps, LED has the advantages of high electro-optical conversion rate, low working voltage, small size, and long life.

However, the current thyristor dimming LED driving circuit has the following problems: the thyristor dimmer has poor compatibility, the transformer structure is complicated, and it cannot be compatible with isolated and non-isolated applications. Therefore, a new type of silicon controlled dimming LED driving circuit is needed.

In view of the above-mentioned problems, this creation provides a novel LED driving circuit.

The LED driving circuit according to this creative embodiment includes an AC input rectification filter circuit, a sensing control circuit, a power conversion transmission transformer, and an output rectification filter circuit, wherein the sensing control circuit includes: a control chip, including dimming information sensing Pin, external power MOS field effect transistor gate drive pin, internal power MOS field effect transistor drain pin, and output information sampling pin; dimming signal acquisition circuit, the first and second ends of the dimming signal acquisition circuit Respectively connected to the second output terminal and the first output terminal of the AC input rectification filter circuit, the third terminal of the dimming signal acquisition circuit is connected to the dimming information sensing pin, and the fourth terminal of the dimming signal acquisition circuit is grounded; the start circuit , The first end of the starter circuit is connected to the third output end of the AC input rectification filter circuit and the first end of the power conversion transmission transformer, the second end of the starter circuit is grounded, and the third end of the starter circuit is connected to the external power MOS field effect Transistor gate drive pin; power MOS field effect transistor, power The drain of the MOS field effect transistor is connected to the second end of the power conversion transmission transformer, and the gate of the power MOS field effect transistor is connected to the external power MOS field effect transistor gate drive pin, the source of the power MOS field effect transistor The pole is connected to the drain pin of the internal power MOS field effect transistor; and the output information sampling circuit. The first end of the output information sampling circuit is connected to the second end of the power conversion transmission transformer, and the second end of the output information sampling circuit is connected to the output The information sampling pin, the third terminal of the output information sampling circuit is grounded.

Compared with the traditional thyristor dimming LED driving circuit, the LED driving circuit according to this creative embodiment has the following advantages: achieving high thyristor dimmer compatibility (compatible with a variety of thyristor dimmers) , Realize the simplification of transformer structure (transformer non-isolated single winding or isolated dual winding application), compatible with non-isolated applications and isolated applications, and compatible with SCR dimming (leading edge/back edge dimming mode) applications and non-dimming application.

100, 200: LED drive circuit

110, 210: AC input rectifier filter circuit

120, 220: Sensing control circuit

130,230: Power conversion transmission transformer

140, 240: output rectifier filter circuit

1201,2201: dimming signal acquisition circuit

1202, 2202: start circuit

1203, 2203: Output information sampling circuit

2301: Absorption circuit

AC: AC power

C1, C5: filter capacitor

C2: Loop compensation capacitor

C3, C4, C6: capacitance

COMP: Internal loop compensation pin

CS: Output current sensing pin

D1: The first rectifier diode

D2: The second rectifier diode

D3: The third rectifier diode

D4: The fourth rectifier diode

D5: output rectifier diode

D6: Diode

DIM: Dimming Information Sensor Foot

DIM1: Triac dimmer

F1: Fuse

FB: Output information sampling pin

GATE: External power MOS field effect transistor gate drive pin

GND: ground pin

L1: Inductance

N _P : Primary winding

N _S : secondary winding

Q1: Power MOS field effect transistor

R1, R2, R3, R4, R5, R6, R7, R _CS : resistance

SW: Internal power MOS field effect transistor drain pin

T1: Transformer

T, T1, T2, T3, T4, T5: period

U1: control chip

VAC1: The voltage of the second terminal of the thyristor dimmer DIM1

VAC2: The voltage of the second input terminal of the AC input rectifier filter circuit

VDD: chip power supply pin

VIN: DC voltage

V _AC : AC voltage

V _CS : The voltage across the resistor R _CS

V _FB : Output information sampling pin FB voltage

This creation can be better understood from the following description of the specific implementation of this creation in combination with the diagrams, in which:

Fig. 1 shows a schematic structural diagram of a non-isolated application of an LED driving circuit according to an embodiment of the present creation;

Figure 2 shows a schematic structural diagram of an isolation application of an LED drive circuit according to an embodiment of the present creation;

Fig. 3 shows a schematic diagram of a working state waveform of an LED driving circuit according to an embodiment of the present creation;

Fig. 4 shows a schematic diagram of the waveform of the leading-edge dimming working mode of the LED driving circuit according to an embodiment of the present creation; and

Fig. 5 shows a schematic waveform diagram of the trailing edge dimming working mode of the LED driving circuit according to an embodiment of the present creation.

The features and exemplary embodiments of various aspects of the present creation will be described in detail below with reference to the drawings. The example implementation can be implemented in a variety of forms, and should not be construed as being limited to this article On the contrary, these implementations are provided to make this creation more comprehensive and complete, and to fully convey the concept of example implementations to those skilled in the art. In the drawings, the size of areas and components may be exaggerated for clarity. In addition, in the drawings, the same drawing symbols indicate the same or similar structures, and thus their detailed descriptions will be omitted.

In addition, the described features, structures, or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to give a sufficient understanding of the embodiments of the present creation. However, those skilled in the art will realize that the technical solution of the present creation can be implemented without one or more of the specific details, or other methods, elements, materials, etc. can be used. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring the main technical ideas of this creation.

The exemplary embodiment of this creation is described in detail below in conjunction with the drawings.

Fig. 1 shows a schematic structural diagram of a non-isolated application of an LED driving circuit according to an embodiment of the present creation. As shown in FIG. 1, the LED driving circuit 100 may include an alternating current (AC, Alternating Current) input rectification filter circuit 110, a sensing control circuit 120, a power conversion transmission transformer 130, and an output rectification filter circuit 140.

First, the AC input rectification filter circuit 110 in the LED drive circuit 100 shown in FIG. 1 will be described in detail below. Specifically, the AC input rectification filter circuit 110 may include a fuse, a thyristor dimmer, a rectifier diode, and a filter capacitor, which are used to rectify and filter the input AC power. As an example, as shown in FIG. 1, the AC input rectification filter circuit 110 may include a fuse F1, a thyristor dimmer DIM1, a first rectifier diode D1, a second rectifier diode D2, and a third rectifier diode. D3, the fourth rectifier diode D4 and the filter capacitor C1. The first rectifier diode D1 and the third rectifier diode D3 can be connected in series to form a first series circuit, the second rectifier diode D2 and the fourth rectifier diode D4 can be connected in series to form a second series circuit, the first series circuit , The second series circuit and the filter capacitor C1 can be connected in parallel with each other.

The first input terminal of the AC input rectifier filter circuit 110 can be connected to the positive electrode of the AC power source AC, and can be connected to the first terminal of the thyristor dimmer DIM1 and the second terminal of the thyristor dimmer DIM1 via the fuse F1 It can be connected to the first output terminal of the AC input rectification filter circuit 110 and the common terminal of the first rectification diode D1 and the third rectification diode D3, The second input terminal of the AC input rectification filter circuit 110 may be connected to the negative electrode of the AC power supply AC, the second output terminal of the AC input rectification filter circuit 110, and the common of the second rectifier diode D2 and the fourth rectifier diode D4. The third output terminal of the AC input rectification filter circuit 110 can be connected to the negative poles of the first rectifier diode D1 and the second rectifier diode D2 and the first end of the filter capacitor C1, the third rectifier diode D3 and The anode of the fourth rectifier diode D4 and the second end of the filter capacitor C1 are grounded.

It should be understood that although FIG. 1 shows that the AC input rectification filter circuit 110 in the LED drive circuit 100 may include four rectifier diodes (D1, D2, D3, and D4), in other embodiments, the AC input The rectifying and filtering circuit 110 may include any suitable number of rectifying diodes (for example, two rectifying diodes). In addition, the fuse F1 of the AC input rectification filter circuit 110 in the LED driving circuit 100 can also be replaced by a fuse resistor, a wire-wound resistor, or an inductor.

The sensing control circuit 120 in the LED driving circuit 100 shown in FIG. 1 will be described in detail below. Specifically, the sensing control circuit 120 may include a control chip U1, a dimming signal acquisition circuit 1201, a startup circuit 1202, a power MOS field effect transistor Q1, and an output information sampling circuit 1203.

The control chip U1 may include a dimming information sensing pin DIM, an external power MOS field effect transistor gate driving pin GATE, an internal power MOS field effect transistor drain pin SW, and an output information sampling pin FB.

Specifically, the dimming information sensing pin DIM can be used to sense the dimming information provided by the thyristor dimmer DIM1 in the AC input rectification filter circuit 110 for dimming. For example, the dimming information sensing pin DIM can be connected to the dimming signal acquisition circuit 1201 to sense the dimming information provided by the thyristor dimmer DIM1 in the AC input rectification filter circuit 110 through the dimming signal acquisition circuit 1201 . The external power MOS field effect transistor gate drive pin GATE can be used to drive the gate of the power MOS field effect transistor outside the control chip U1. For example, the external power MOS field effect transistor gate drive pin GATE can be connected to the startup circuit 1202 and the gate of the power MOS field effect transistor Q1 outside the control chip U1 to control the on and off of the power MOS field effect transistor Q1. Off. Internal power MOS field effect transistor drain pin SW can be a control transistor The drain of the power MOS field effect transistor inside U1. The output information sampling pin FB can be used to sample the output information. For example, the output information sampling pin FB can be connected to the output information sampling circuit 1203.

The first terminal and the second terminal of the dimming signal acquisition circuit 1201 can be connected to the second output terminal and the first output terminal of the AC input rectification filter circuit 110, respectively, and the third terminal of the dimming signal acquisition circuit 1201 can be connected to the control chip The dimming information sensing pin DIM of U1, and the fourth terminal of the dimming signal collection circuit 1201 can be grounded.

Specifically, the dimming signal collection circuit 1201 may include a resistor. As an example, the dimming signal collection circuit 1201 may include a resistor R1, a resistor R2, and a resistor R3. The first end of the resistor R1 can be connected to the first end of the dimming signal collection circuit 1201, and the first end of the resistor R2 can be connected To the second end of the dimming signal collection circuit 1201, the second end of the resistor R1 can be connected to the second end of the resistor R2, the first end of the resistor R3, and the third end of the dimming signal collection circuit 1201, the second end of the resistor R3 The two terminals can be connected to the fourth terminal of the dimming signal collection circuit 1201.

The first terminal of the starting circuit 1202 may be connected to the third output terminal of the AC input rectification filter circuit 110 and the first terminal of the power conversion transmission transformer 130, the second terminal of the starting circuit 1202 may be grounded, and the third terminal of the starting circuit 1202 may be Connect to the external power MOS field effect transistor gate drive pin GATE of the control chip U1.

Specifically, the startup circuit 1202 may include a resistor and a capacitor. As an example, the startup circuit 1202 may include a resistor R4 and a capacitor C4, wherein the first end of the resistor R4 may be connected to the first end of the startup circuit 1202, the second end of the resistor R4 may be connected to the first end of the capacitor C4 and the start The third terminal of the circuit 1202 and the second terminal of the capacitor C4 can be connected to the second terminal of the startup circuit 1202.

The drain of the power MOS field effect transistor Q1 can be connected to the second terminal of the power conversion transmission transformer 130, and the gate of the power MOS field effect transistor Q1 can be connected to the external power MOS field effect transistor gate driver of the control chip U1 Pin GATE, the source of the power MOS field effect transistor Q1 can be connected to the internal power MOS field effect transistor drain pin SW of the control chip U1. As an example, the power MOS field effect transistor Q1 may be a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET).

The first end of the output information sampling circuit 1203 can be connected to the second end of the power conversion transmission transformer 130, the second end of the output information sampling circuit 1203 can be connected to the output information sampling pin FB of the control chip U1, and the output information sampling circuit 1203 The third terminal can be grounded.

Specifically, the output information sampling circuit 1203 may include a resistor. As an example, the output information sampling circuit 1203 may include a resistor R5 and a resistor R6, wherein the first end of the resistor R5 may be connected to the first end of the output information sampling circuit 1203, and the second end of the resistor R5 may be connected to the output information sampling circuit The second terminal of 1203 and the first terminal of resistor R6, and the second terminal of resistor R6 can be connected to the third terminal of output information sampling circuit 1203.

In addition, as an example, the control chip U1 may also include an internal loop compensation pin COMP, a chip power supply pin VDD, a ground pin GND, and an output current sensing pin CS. Specifically, the internal loop compensation pin COMP can be used for loop compensation. For example, the internal loop compensation pin COMP can be grounded via the loop compensation capacitor C2. The chip power supply pin VDD can be used to power the control chip U1. For example, the chip power supply pin VDD can be grounded via the capacitor C3. The ground pin GND can be used as the reference ground of the control chip U1. The output current sensing pin CS can be used to set the output current. For example, the output current sensing pin CS can be grounded via a resistor R _CS , and the control chip U1 can set the output current value by adjusting the resistance value of the resistor R _CS .

The power conversion transmission transformer 130 in the LED driving circuit 100 shown in FIG. 1 will be described in detail below. Specifically, the power conversion transmission transformer 130 may include an inductor. As an example, the power conversion transfer transformer 130 may include an inductor L1. The first end of the inductor L1 can be used as the first end of the power conversion and transmission transformer 130, and is connected to the third output end of the AC input rectification filter circuit 110, the first end of the startup circuit 1202 in the sensing control circuit 120, and the output rectification filter. The first end of the circuit 140. The second end of the inductor L1 can be used as the second end of the power conversion transmission transformer 130, connected to the drain of the power MOS field effect transistor Q1 in the sensing control circuit 120, and the output information sampling circuit 1203 in the sensing control circuit 120 The first terminal of the output rectifier filter circuit 140 and the second terminal.

The output rectifying filter circuit 140 in the LED driving circuit 100 shown in FIG. 1 will be described in detail below. Specifically, the output rectification filter circuit 140 may include an output rectification diode and a filter capacitor. As an example, the output rectification filter circuit 140 may include output rectification two Polar body D5 and filter capacitor C5. The positive pole of the output rectifier diode D5 can be used as the second end of the output rectification filter circuit 140 and is connected to the second end of the power conversion and transmission transformer 130, that is, the second end of the inductor L1. The negative pole of the output rectifier diode D5 can be connected to the positive pole of the filter capacitor C5. The negative electrode of the filter capacitor C5 can be used as the first terminal of the output rectification filter circuit 140 and is connected to the first terminal of the power conversion and transmission transformer 130, that is, the first terminal of the inductor L1.

In addition, the LED load circuit can be connected to both ends of the filter capacitor C5. For example, the first terminal of the LED load circuit can be connected to the positive electrode of the filter capacitor C5, and the second terminal of the LED load circuit can be connected to the negative electrode of the filter capacitor C5.

The LED load circuit may be an LED light string including one or more LEDs. The LED light string may include any suitable number of LED light beads. In the embodiment shown in FIG. 1, the LED lamp beads included in the LED lamp string are shown as being connected together in series, but in other embodiments, the LED lamp beads may also be connected in parallel. In addition, the LED lamp bead can be a direct-type or side-entry LED lamp bead, which is not limited in this creation. In the LED driving circuit as shown in FIG. 1, the first end of the LED load circuit can be connected to the anode of the LED light string, and the second end of the LED load circuit can be connected to the cathode of the LED light string.

Fig. 2 shows a schematic structural diagram of an isolation application of an LED driving circuit according to an embodiment of the present creation. As shown in FIG. 2, the LED driving circuit 200 may include an alternating current (AC) input rectification filter circuit 210, a sensing control circuit 220, a power conversion transmission transformer 230, and an output rectification filter circuit 240.

First, the AC input rectification filter circuit 210 in the LED drive circuit 200 shown in FIG. 2 will be described in detail below. Specifically, the AC input rectification and filter circuit 210 may include a fuse, a thyristor dimmer, a rectifier diode, and a filter capacitor, for rectifying and filtering the input AC power. As an example, as shown in FIG. 2, the AC input rectification filter circuit 210 may include a fuse F1, a silicon controlled dimmer DIM1, a first rectifier diode D1, a second rectifier diode D2, and a third rectifier diode. D3, the fourth rectifier diode D4 and the filter capacitor C1. The first rectifier diode D1 and the third rectifier diode D3 can be connected in series to form a first series circuit, the second rectifier diode D2 and the fourth rectifier diode D4 can be connected in series to form a second series circuit, the first series circuit , The second series circuit and the filter capacitor C1 can be connected in parallel with each other.

The first input terminal of the AC input rectifier filter circuit 210 can be connected to the positive electrode of the AC power supply, and can be connected to the first terminal of the thyristor dimmer DIM1 and the second terminal of the thyristor dimmer DIM1 via the fuse F1 It can be connected to the first output terminal of the AC input rectifying and filtering circuit 210 and the common terminal of the first rectifying diode D1 and the third rectifying diode D3, and the second input terminal of the AC input rectifying and filtering circuit 210 can be connected to the AC The negative pole of the power supply AC, the second output end of the AC input rectification and filter circuit 210, and the common end of the second rectification diode D2 and the fourth rectification diode D4, the third output end of the AC input rectification and filter circuit 210 may be connected To the cathode of the first rectifier diode D1 and the second rectifier diode D2 and the first end of the filter capacitor C1, the anode of the third rectifier diode D3 and the fourth rectifier diode D4 and the first end of the filter capacitor C1 The two ends are grounded.

It should be understood that although FIG. 2 shows that the AC input rectification filter circuit 210 in the LED drive circuit 200 may include four rectifier diodes (D1, D2, D3, and D4), in other embodiments, the AC input The rectifying and filtering circuit 210 may include any suitable number of rectifying diodes (for example, two rectifying diodes). In addition, the fuse F1 of the AC input rectification filter circuit 210 in the LED driving circuit 200 can also be replaced by a fuse resistor, a wire-wound resistor, or an inductor.

The sensing control circuit 220 in the LED driving circuit 200 shown in FIG. 2 will be described in detail below. Specifically, the sensing control circuit 220 may include a control chip U1, a dimming signal acquisition circuit 2201, a startup circuit 2202, a power MOS field effect transistor Q1, and an output information sampling circuit 2203.

The control chip U1 may include a dimming information sensing pin DIM, an external power MOS field effect transistor gate driving pin GATE, an internal power MOS field effect transistor drain pin SW, and an output information sampling pin FB.

Specifically, the dimming information sensing pin DIM can be used to sense dimming information provided by the thyristor dimmer DIM1 in the AC input rectification filter circuit 210 for dimming. For example, the dimming information sensing pin DIM can be connected to the dimming signal acquisition circuit 2201 to sense the dimming information provided by the thyristor dimmer DIM1 in the AC input rectification filter circuit 210 through the dimming signal acquisition circuit 2201 . External power MOS field effect transistor gate drive pin GATE can be used Drive the gate of the power MOS field effect transistor outside the control chip U1. For example, the external power MOS field effect transistor gate drive pin GATE can be connected to the startup circuit 2202 and the gate of the power MOS field effect transistor Q1 outside the control chip U1 to control the on and off of the power MOS field effect transistor Q1 Off. The internal power MOS field effect transistor drain pin SW can be the drain of the power MOS field effect transistor inside the control chip U1. The output information sampling pin FB can be used to sample the output information. For example, the output information sampling pin FB can be connected to the output information sampling circuit 2203.

The first terminal and the second terminal of the dimming signal collection circuit 2201 can be connected to the second output terminal and the first output terminal of the AC input rectification filter circuit 210, respectively, and the third terminal of the dimming signal collection circuit 2201 can be connected to the control chip The dimming information sensing pin DIM of U1, and the fourth terminal of the dimming signal collection circuit 2201 can be grounded.

Specifically, the dimming signal collection circuit 2201 may include a resistor. As an example, the dimming signal collection circuit 2201 may include a resistor R1, a resistor R2, and a resistor R3, where the first end of the resistor R1 can be connected to the first end of the dimming signal collection circuit 2201, and the first end of the resistor R2 can be connected To the second end of the dimming signal collection circuit 2201, the second end of the resistor R1 can be connected to the second end of the resistor R2, the first end of the resistor R3, and the third end of the dimming signal collection circuit 2201, the second end of the resistor R3 The two terminals can be connected to the fourth terminal of the dimming signal collection circuit 2201.

The first terminal of the starting circuit 2202 can be connected to the third output terminal of the AC input rectification filter circuit 210 and the first terminal of the power conversion transmission transformer 230, the second terminal of the starting circuit 2202 can be grounded, and the third terminal of the starting circuit 2202 can be Connect to the external power MOS field effect transistor gate drive pin GATE of the control chip U1.

Specifically, the startup circuit 2202 may include a resistor and a capacitor. As an example, the starting circuit 2202 may include a resistor R4 and a capacitor C4, wherein the first end of the resistor R4 may be connected to the first end of the starting circuit 2202, the second end of the resistor R4 may be connected to the first end of the capacitor C4 and the start The third terminal of the circuit 2202 and the second terminal of the capacitor C4 can be connected to the second terminal of the starting circuit 2202.

The drain of the power MOS field effect transistor Q1 can be connected to the second end of the power conversion transmission transformer 230, and the gate of the power MOS field effect transistor Q1 can be connected to the control transistor. The external power MOS field effect transistor gate drive pin GATE of the chip U1, and the source of the power MOS field effect transistor Q1 can be connected to the internal power MOS field effect transistor drain pin SW of the control chip U1. As an example, the power MOS field effect transistor Q1 may be a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET).

The first terminal of the output information sampling circuit 2203 can be connected to the second terminal of the power conversion transmission transformer 230 and the drain of the power MOS field effect transistor Q1, and the second terminal of the output information sampling circuit 2203 can be connected to the output of the control chip U1 The information sampling pin FB, the third terminal of the output information sampling circuit 2203 can be grounded.

Specifically, the output information sampling circuit 2203 may include a resistor. As an example, the output information sampling circuit 2203 may include a resistor R5 and a resistor R6, wherein the first end of the resistor R5 may be connected to the first end of the output information sampling circuit 2203, and the second end of the resistor R5 may be connected to the output information sampling circuit The second end of 2203 and the first end of resistor R6, and the second end of resistor R6 can be connected to the third end of output information sampling circuit 2203.

In addition, as an example, the control chip U1 may also include an internal loop compensation pin COMP, a chip power supply pin VDD, a ground pin GND, and an output current sensing pin CS. Specifically, the internal loop compensation pin COMP can be used for loop compensation. For example, the internal loop compensation pin COMP can be grounded via the loop compensation capacitor C2. The chip power supply pin VDD can be used to power the control chip U1. For example, the chip power supply pin VDD can be grounded via the capacitor C3. The ground pin GND can be used as the reference ground of the control chip U1. The output current sensing pin CS can be used to set the output current. For example, the output current sensing pin CS can be grounded via a resistor R _CS , and the control chip U1 can set the output current value by adjusting the resistance value of the resistor R _CS .

The power conversion transmission transformer 230 in the LED driving circuit 200 shown in FIG. 2 will be described in detail below. Specifically, the power conversion transmission transformer 230 may include an absorption circuit 2301 and a transformer T1, where the transformer T1 may realize input and output isolation. For example, the absorption circuit 2301 may include a resistor, a capacitor, and a diode, and the transformer T1 may include a primary winding and a secondary winding. As an example, as shown in FIG. 2, the absorption circuit 2301 may include a resistor R7, a capacitor C6, and a diode D6, and the transformer T1 may include a primary winding N _P and a secondary winding N _S.

The first end of the resistor R7 and the first end of the capacitor C6 can be used as the first end of the power conversion and transmission transformer 230, which is connected to the third output end of the AC input rectification filter circuit 210, the first end of the starting circuit 2202, and the transformer T1 a first end of the primary winding of the negative electrode N _P, and the second terminal of resistor R7 and capacitor C6 may be connected to a second end, and the diode D6, the cathode of diode D6 may be transmitted as the second end of the power converter transformer 230, , Connected to the drain of the power MOS field effect transistor Q1, the first end of the output information sampling circuit 2203, and the second end of the primary winding N _P of the transformer T1, the secondary winding N _{S of the} transformer T1 can be connected to the output rectifier Filter circuit 240.

The output rectifying and filtering circuit 240 in the LED driving circuit 200 shown in FIG. 2 will be described in detail below. Specifically, the output rectification filter circuit 240 may include an output rectification diode and a filter capacitor. As an example, the output rectification filter circuit 240 may include an output rectification diode D5 and a filter capacitor C5. The positive pole of the output rectifier diode D5 can be used as the first terminal of the output rectifier filter circuit 240, which is connected to the first terminal of the secondary winding _NS of the transformer T1, and the negative pole of the output rectifier diode D5 can be connected to the filter capacitor C5. The positive electrode and the negative electrode of the filter capacitor C5 can be used as the second end of the output rectification filter circuit 240 and connected to the second end of the secondary winding N _S.

In addition, the LED load circuit can be connected to both ends of the filter capacitor C5. For example, the first terminal of the LED load circuit can be connected to the positive electrode of the filter capacitor C5, and the second terminal of the LED load circuit can be connected to the negative electrode of the filter capacitor C5.

The LED load circuit may be an LED light string including one or more LEDs. The LED light string may include any suitable number of LED light beads. In the embodiment shown in FIG. 2, the LED lamp beads included in the LED lamp string are shown as being connected together in series, but in other embodiments, the LED lamp beads may also be connected in parallel. In addition, the LED lamp bead can be a direct-type or side-entry LED lamp bead, which is not limited in this creation. In the LED driving circuit shown in FIG. 2, the first end of the LED load circuit can be connected to the anode of the LED light string, and the second end of the LED load circuit can be connected to the cathode of the LED light string.

The working state of the LED driving circuit (isolated application or non-isolated application) according to the embodiment of the invention described above with reference to FIGS. 1 and 2 is divided into a non-dimming working mode and a dimming working mode.

Figure 3 shows the non-function of the LED drive circuit according to an embodiment of the present creation Waveform diagram of dimming working mode. The following first describes the working process of the non-dimming working mode of the LED driving circuit according to an embodiment of the present creation, which can be divided into four stages, which are described in detail below.

The first stage: the AC input voltage of the AC power source AC is rectified and filtered by the AC input rectification filter circuit to become a DC voltage (for example, a sine wave) VIN. As the DC voltage VIN gradually increases, the capacitor C4 can be charged through the following loop: filter capacitor C1→resistor R4→capacitor C4→ground pin GND of control chip U1→filter capacitor C1. As the capacitor C4 is gradually charged, the power MOS field effect transistor Q1 can be gradually turned on. As the power MOS field effect transistor Q1 is gradually turned on, the DC voltage VIN can charge the external capacitor C3 of the chip power supply pin VDD of the control chip U1 through the following loop: filter capacitor C1 → inductance L1/ primary winding of transformer T1 N _P → Drain of power MOS field effect transistor Q1 → source of power MOS field effect transistor Q1 → internal power MOS field effect transistor drain pin SW of control chip U1 → chip power supply pin VDD of control chip U1 → capacitor C3 → Ground pin GND of control chip U1→capacitor C1. For example, when the voltage of the external capacitor C3 of the chip power supply pin VDD of the control chip U1 is higher than the turn-on voltage of the control chip U1, the control chip U1 can start to work. Then, the control chip U1 can sense dimming information (for example, including voltage value and time value) through the dimming signal collection circuit connected to the dimming information sensing pin DIM, and then determine the LED based on the sensed dimming information Whether the driving circuit turns on the thyristor dimmer DIM1, and then enters the dimming working mode or the non-dimming working mode (in this example, entering the non-dimming working mode) according to the judgment result. For example, the dimming signal acquisition circuit can be a sampling resistor divider circuit, and the voltage value in the dimming information can be calculated based on the following formula: (R3×VAC1)/(R3+R2) and (R3×VAC2)/(R3 +R1), where VAC1 is the voltage at the second terminal of the thyristor dimmer DIM1, and VAC2 is the voltage at the second input terminal of the AC input rectifier filter circuit, as shown in Figs. 1 and 2.

The second stage: the control chip U1 can control its internal power MOS field effect transistor (for example, MOSFET) to turn on, so that the DC voltage VIN can be stored in the inductor L1/transformer T1 through the following loop: filter capacitor C1→inductance L1/ Primary winding N _{P of} transformer T1 → Drain of power MOS field effect transistor Q1 → Source of power MOS field effect transistor Q1 → Internal power MOS field effect transistor drain pin SW of control chip U1 → Control chip U1 Output current sensing pin CS → resistance R _CS → ground pin GND of the control chip U1 → filter capacitor C1. Voltage threshold value U1 may control the wafer output current sensing pin CS provided by the external resistor R & lt _CS to control the energy L1 / stored in the inductance of the transformer T1. For example, when the control chip U1 senses that the voltage across the resistor R _CS reaches the voltage threshold set by the control chip U1, the control chip U1 can control its internal power MOS field effect transistor (for example, MOSFET) to turn off, so that The above-mentioned loop is disconnected, and the energy storage for the inductor L1/transformer T1 is stopped. In addition, by changing the value of the resistor R _CS , the output current can be adjusted.

The third stage: The control chip U1 can control its internal power MOS field effect transistor (for example, MOSFET) to turn off, so that the energy stored in the inductor L1/transformer T1 can release the energy to the output through the following loop: inductor L1/ The secondary winding N _{S of the} transformer T1 → the output rectifier diode D5 → the filter capacitor C5 → the inductance L1/ the secondary winding N _{S of the} transformer T1. The control chip U1 can sense output information (for example, energy transfer time (demagnetization time), and output voltage) through the output information sampling circuit connected to the output information sampling pin FB, combined with the output current and loop based on the resistor R _CS setting The loop compensation and other information provided by the compensation capacitor C2 can achieve output constant current and output overvoltage protection by controlling the internal control circuit of the chip U1 (which can use any appropriate algorithm, and this creation does not limit this).

The fourth stage: When the AC power supply AC is turned off and the DC voltage VIN voltage drops, or when the control chip U1 triggers protection and forcibly shuts off the power supply circuit of the chip power supply pin VDD, the control chip U1's chip power supply pin VDD external capacitor C3 The voltage drops accordingly. When the voltage of the capacitor C3 is lower than the minimum operating voltage threshold set by the control chip U1, the control chip U1 can stop working until the AC power source AC is turned on again or the protection reset is released, and the control chip U1 can return to the first stage of work.

The control chip U1 can work in a loop from the first stage to the fourth stage. The two working state waveforms from top to bottom in FIG. 3 sequentially show the waveforms of the voltage V _CS across the resistor R _CS and the voltage V _FB of the output information sampling pin FB of the control chip U1.

Figure 4 shows a schematic diagram of the waveforms of the leading-edge dimming operation mode of the LED drive circuit according to an embodiment of the invention, and Figure 5 shows the trailing-edge dimming operation mode of the LED drive circuit according to an embodiment of the invention Schematic diagram of the waveform. The following first describes the creation based on this The working process of the leading edge or trailing edge dimming working mode of the LED drive circuit of an embodiment can be divided into seven stages, which are described in detail below.

The first stage: the AC input voltage of the AC power source AC is rectified and filtered by the AC input rectification filter circuit to become a DC voltage (for example, a sine wave) VIN. As the DC voltage VIN gradually increases, the capacitor C4 can be charged through the following loop: filter capacitor C1→resistor R4→capacitor C4→ground pin GND of control chip U1→filter capacitor C1. As the capacitor C4 is gradually charged, the power MOS field effect transistor Q1 can be gradually turned on. As the power MOS field effect transistor Q1 is gradually turned on, the DC voltage VIN can charge the external capacitor C3 of the chip power supply pin VDD of the control chip U1 through the following loop: filter capacitor C1 → inductance L1/ primary winding of transformer T1 N _P → Drain of power MOS field effect transistor Q1 → source of power MOS field effect transistor Q1 → internal power MOS field effect transistor drain pin SW of control chip U1 → chip power supply pin VDD of control chip U1 → capacitor C3 → Ground pin GND of control chip U1→capacitor C1. For example, when the voltage of the external capacitor C3 of the chip power supply pin VDD of the control chip U1 is higher than the turn-on voltage of the control chip U1, the control chip U1 can start to work. Then, the control chip U1 can sense dimming information (for example, including voltage value and time value) through the dimming signal collection circuit connected to the dimming information sensing pin DIM, and then determine the LED based on the sensed dimming information Whether the driving circuit turns on the thyristor dimmer DIM1, and then enters the dimming working mode or the non-dimming working mode (in this example, the dimming working mode) according to the judgment result. For example, the dimming signal acquisition circuit can be a sampling resistor divider circuit, and the voltage value in the dimming information can be calculated based on the following formula: (R3×VAC1)/(R3+R2) and (R3×VAC2)/(R3 +R1), where VAC1 is the voltage at the second terminal of the thyristor dimmer DIM1, and VAC2 is the voltage at the second input terminal of the AC input rectifier filter circuit, as shown in Figs. 1 and 2.

The second stage: the moment the AC power supply AC is turned on and the thyristor dimmer DIM1 is turned on, the control chip U1 can control its internal power MOS field-effect transistor (for example, MOSFET) during the period T1, and the output is constant through the following loop Current: filter capacitor C1 → inductance L1/ primary winding N _{P of} transformer T1 → drain of power MOS field effect transistor Q1 → source of power MOS field effect transistor Q1 → internal power MOS field effect transistor of control chip U1 The drain pin SW→the ground pin GND of the control chip U1→the filter capacitor C1, so as to speed up the stable and fast conduction of the thyristor dimmer DIM1.

The third stage: in the period T2, the control chip U1 can work according to the second stage and the third stage of the non-dimming working mode of the LED driving circuit described above with reference to FIG. 4 to transmit energy to the output terminal. As shown in FIGS. 4 and 5, the period T2 only exists in the leading edge dimming working mode, and there is no period T2 in the trailing edge dimming working mode.

The fourth stage: the control chip U1 suspends work during the period T3.

The fifth stage: the control chip U1 operates according to the third stage (that is, according to the second stage and the third stage of the non-dimming operating mode of the LED driving circuit described above with reference to FIG. 4) in the period T4. During the entire period T, the control chip U1 can sense dimming information (for example, including voltage value and time value) through the dimming signal acquisition circuit connected to the dimming information sensing pin DIM, and then based on the sensed dimming information Information to determine the current phase cut angle of the thyristor dimmer DIM1. Further, the size of the periods T2 and T4 can be determined based on the size of the phase cut angle, so as to realize the dimming function. For example, the dimming signal acquisition circuit can be a sampling resistor divider circuit, and the voltage value in the dimming information can be calculated based on the following formula: (R3×VAC1)/(R3+R2) and (R3×VAC2)/(R3 +R1), where VAC1 is the voltage at the second terminal of the thyristor dimmer DIM1, and VAC2 is the voltage at the second input terminal of the AC input rectifier filter circuit, as shown in Figs. 1 and 2.

Sixth stage: During the period T5, the control chip U1 works according to the second stage to ensure that the lowest current that maintains the conduction of the thyristor dimmer DIM1 is provided, until it returns to the second stage to work in the period T1. The high compatibility of the thyristor dimmer DIM1 is mainly reflected in the sine wave period T after the entire phase cut (leading edge dimming working mode T=T1+T2+T3+T4+T5, trailing edge dimming working mode T= In T1+T3+T4+T5), the control chip U1 can correspond the output current to the average current in the input period T, and concentrate the output current in periods T2 and T4 (leading edge dimming mode) or period T4 (back edge) Dimming working mode) output. This not only ensures that the average output current in the period T remains unchanged, but also increases the average value of the input current in the periods T2 and T4 (leading edge dimming operating mode) or period T4 (back edge dimming operating mode). During periods T2 and T4 (leading edge dimming operating mode) or period T4 (rear edge dimming operating mode), ensure that the input average current is not lower than the minimum current required to maintain the thyristor dimmer DIM1 conducting, thereby avoiding control LED flicker caused by silicon dimmer DIM1 turned off. The control in the period T3 can prevent the thyristor dimmer DIM1 from turning off. The LED driving circuit circulates at each stage in the above period T, so as to achieve high compatibility of the thyristor dimmer.

The seventh stage: When the AC power supply AC is turned off and the DC voltage VIN voltage drops, or when the control chip U1 triggers protection and forcibly shuts off the power supply circuit of the chip power supply pin VDD, the control chip U1's chip power supply pin VDD external capacitor C3 The voltage drops accordingly. When the voltage of the capacitor C3 is lower than the minimum operating voltage threshold set by the control chip U1, the control chip U1 can stop working until the AC power source AC is turned on again or the protection reset is released, and the control chip U1 can return to the first stage of work.

The three working state waveforms from top to bottom in FIG. 4 and FIG. 5 all show the waveforms of the DC voltage VIN, the AC voltage V _AC , and the voltage V _CS across the resistor R _CS in sequence.

Compared with the traditional thyristor dimming LED driving circuit, the LED driving circuit according to this creative embodiment has the following advantages: achieving high thyristor dimmer compatibility (compatible with a variety of thyristor dimmers) , Realize the simplification of transformer structure (transformer non-isolated single winding or isolated dual winding application), compatible with non-isolated applications and isolated applications, and compatible with SCR dimming (leading edge/back edge dimming mode) applications and non-dimming application.

This creation can be realized in other concrete forms without departing from its spirit and essential characteristics. Therefore, the current embodiments are regarded as illustrative rather than restrictive in all aspects, and the scope of this creation is defined by the scope of the appended patent application rather than the above description, and the meaning and equivalents falling within the scope of the patent application All changes within the scope of things are thus included in the scope of this creation.

100: LED drive circuit

110: AC input rectifier filter circuit

120: Sensing control circuit

130: power conversion transmission transformer

140: output rectifier filter circuit

1201: Dimming signal acquisition circuit

1202: start circuit

1203: Output information sampling circuit

AC: AC power

C1, C5: filter capacitor

C2: Loop compensation capacitor

C3, C4: Capacitance

COMP: Internal loop compensation pin

CS: Output current sensing pin

D1: The first rectifier diode

D2: The second rectifier diode

D3: The third rectifier diode

D4: The fourth rectifier diode

D5: output rectifier diode

DIM: Dimming Information Sensor Foot

DIM1: Triac dimmer

F1: Fuse

FB: Output information sampling pin

GATE: External power MOS field effect transistor gate drive pin

GND: ground pin

L1: Inductance

Q1: Power MOS field effect transistor

R1, R2, R3, R4, R5, R6, R _CS : resistance

SW: Internal power MOS field effect transistor drain pin

U1: control chip

VAC1: The voltage of the second terminal of the thyristor dimmer DIM1

VAC2: The voltage of the second input terminal of the AC input rectifier filter circuit

VDD: chip power supply pin

VIN: DC voltage

Claims (18)

An LED drive circuit includes an AC input rectification filter circuit, a sensing control circuit, a power conversion transmission transformer, and an output rectification filter circuit, wherein: The sensing control circuit includes: Control chip, including dimming information sensing pin, external power MOS field effect transistor gate drive pin, internal power MOS field effect transistor drain pin, and output information sampling pin; A dimming signal acquisition circuit, the first end and the second end of the dimming signal acquisition circuit are respectively connected to the second output end and the first output end of the AC input rectification filter circuit, the dimming signal acquisition circuit The third terminal is connected to the dimming information sensing pin, and the fourth terminal of the dimming signal collecting circuit is grounded; A starter circuit, the first end of the starter circuit is connected to the third output end of the AC input rectification filter circuit and the first end of the power conversion transmission transformer, the second end of the starter circuit is grounded, and the starter The third end of the circuit is connected to the external power MOS field effect transistor gate driving pin; A power MOS field effect transistor, the drain of the power MOS field effect transistor is connected to the second end of the power conversion transmission transformer, and the gate of the power MOS field effect transistor is connected to the external power MOS field An effect transistor gate drive pin, the source of the power MOS field effect transistor is connected to the internal power MOS field effect transistor drain pin; and Output information sampling circuit, the first end of the output information sampling circuit is connected to the second end of the power conversion transmission transformer, the second end of the output information sampling circuit is connected to the output information sampling pin, the output The third terminal of the information sampling circuit is grounded. The LED driving circuit according to claim 1, wherein the control chip further includes: Internal loop compensation pin, used for internal loop compensation, grounded via the first capacitor; The chip power supply pin is used to supply power to the control chip and is grounded via the second capacitor; The ground pin is used as the reference ground of the control chip; and The output current sensing pin is used to set the output current and is grounded via the first resistor. The LED driving circuit according to claim 1, wherein the dimming signal acquisition circuit includes a resistor. The LED driving circuit according to claim 3, wherein the resistor includes a first resistor, a second resistor, and a third resistor, wherein the first end of the first resistor is connected to the dimming signal acquisition circuit At the first end, the first end of the second resistor is connected to the second end of the dimming signal collection circuit, and the second end of the first resistor is connected to the second end of the second resistor, the The first end of the third resistor and the third end of the dimming signal collection circuit, and the second end of the third resistor is connected to the fourth end of the dimming signal collection circuit. The LED driving circuit according to claim 1, wherein the starting circuit includes a resistor and a capacitor. The LED driving circuit according to claim 5, wherein the first end of the resistor is connected to the first end of the startup circuit, and the second end of the resistor is connected to the first end of the capacitor and the The third terminal of the startup circuit, and the second terminal of the capacitor is connected to the second terminal of the startup circuit. The LED driving circuit according to claim 1, wherein the output information sampling circuit includes a resistor. The LED driving circuit according to claim 7, wherein the resistor includes a first resistor and a second resistor, wherein the first end of the first resistor is connected to the first end of the output information sampling circuit, so The second end of the first resistor is connected to the second end of the output information sampling circuit and the first end of the second resistor, and the second end of the second resistor is connected to the first end of the output information sampling circuit. Three ends. The LED driving circuit according to claim 1, wherein the AC input rectification filter circuit includes a fuse, a thyristor dimmer, a rectifier electrode, and a filter capacitor. The LED driving circuit according to claim 9, wherein: The rectifier diode includes a first rectifier diode, a second rectifier diode, a third rectifier diode, and a fourth rectifier diode, wherein the first and third rectifier diodes are connected in series Forming a first series circuit, the second and fourth rectifier diodes are connected in series to form a second series circuit, the first series circuit, the second series circuit, and the filter capacitor are connected in parallel; and The first input terminal of the AC input rectification filter circuit is connected to the positive pole of the AC power source, and is connected to the first terminal of the thyristor dimmer via the fuse, and the second terminal of the thyristor dimmer Terminal is connected to the first output terminal of the AC input rectification filter circuit and the common terminal of the first and third rectifier diodes, and the second input terminal of the AC input rectification filter circuit is connected to the AC power supply The negative electrode, the second output end of the AC input rectification and filter circuit, and the common end of the second and fourth rectifier diodes, and the third output end of the AC input rectification and filter circuit is connected to the first and The negative pole of the second rectifier diode and the first end of the filter capacitor, the positive pole of the third and fourth rectifier diodes and the second end of the filter capacitor are grounded. The LED driving circuit according to claim 1, wherein the power conversion transmission transformer includes an inductor. The LED driving circuit according to claim 11, wherein the first end of the inductor is connected to the third output end of the AC input rectification filter circuit, the first end of the start circuit, and the output rectification filter circuit The second end of the inductor is connected to the drain of the power MOS field effect transistor, the first end of the output information sampling circuit, and the second end of the output rectification filter circuit. The LED driving circuit according to claim 12, wherein the output rectification filter circuit includes an output rectification diode and a filter capacitor. The LED driving circuit according to claim 13, wherein the positive electrode of the output rectifying diode is connected to the second end of the inductor, and the negative electrode of the output rectifying diode is connected to the positive electrode of the filter capacitor, The negative electrode of the filter capacitor is connected to the first end of the inductor. The LED driving circuit according to claim 1, wherein the power conversion transmission transformer includes: Absorption circuits, including resistors, capacitors, and diodes; and Transformer, including primary winding and secondary winding. The LED drive circuit according to claim 15, wherein the first end of the resistor and the first end of the capacitor are connected to the third output end of the AC input rectification filter circuit and the first end of the start circuit. End, and the first end of the primary winding, and the second end of the resistor is connected to The second end of the capacitor and the cathode of the diode, the anode of the diode is connected to the drain of the power MOS field effect transistor, the first end of the output information sampling circuit, and the At the second end of the primary winding, the secondary winding is connected to the output rectification filter circuit. The LED driving circuit according to claim 16, wherein the output rectification filter circuit includes an output rectification diode and a filter capacitor. The LED driving circuit according to claim 17, wherein the positive pole of the output rectifying diode is connected to the first end of the secondary winding of the transformer, and the negative pole of the output rectifying diode is connected to the filter The positive pole of the capacitor and the negative pole of the filter capacitor are connected to the second end of the secondary winding of the transformer.

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