TWM589406U - LED drive circuit and control chip - Google Patents

Abstract

This creative embodiment provides an LED (Light Emitting Diode) driving circuit and a control chip. The driving circuit includes a rectifier circuit and a constant current control circuit. The constant current control circuit includes a control chip, including an output current setting pin, a sink Pole pin, input voltage sense pin; voltage divider circuit, connected between the output of the rectifier circuit and the reference ground, its output end is connected to the input voltage sense pin; load module, connected to the output and drain of the rectifier circuit Between the feet; the output capacitor whose first end is connected to the output of the rectifier circuit; the first extended output capacitor discharge time module, connected between the second end of the output capacitor and the drain pin; the second extended output capacitor discharge time The module is connected between the second end of the output capacitor and the output current setting pin; where the input voltage sensing pin is used to judge whether to enter the leading edge dimming mode, trailing edge dimming mode or non-dimming mode. According to the above technical solution, there is no need for an inductive magnetic core, and a small circuit volume and fewer system components are realized.

Description

LED driver circuit and control chip

This creation relates to the technical field of LED (Light Emitting Diode), and more specifically, to an LED driving circuit and a control chip.

Light Emitting Diode (LED) is a semiconductor device that can emit light. Its core is a PN junction. It has the electrical characteristics of ordinary diodes. The luminous flux and current of Light Emitting Diode (LED) The current through the LED is proportional to this feature. It is because of this characteristic that the dimming effect of the LED is unmatched by other traditional lighting. The dimming work of traditional lighting fixtures such as incandescent lamps will reduce its working efficiency, and when the LED is dimming, As the current in the circuit is reduced, the power consumption of certain resistance components will be reduced, thereby improving the luminous efficiency.

However, the traditional LED thyristor dimming scheme usually uses the switching scheme of electrolytic capacitors and inductive magnetic core devices, which will cause the drive circuit to be too large to adapt to small-volume applications such as bulbs and filament lamps. , Causing the system cost to be too high to meet the user's low cost requirements.

In order to solve one or more of the aforementioned technical problems, this creative embodiment provides an LED driving circuit and a control chip, which can realize an LED driving circuit without an inductive magnetic core device, which realizes a small size of the driving circuit, fewer system components, and low cost , To meet the actual application needs of customers.

On the one hand, this creative embodiment provides an LED driving circuit, which may include a rectifier circuit and a constant current control circuit. The rectifier circuit may be used to output direct current, and the constant current control circuit may include a control chip, a voltage divider circuit, a load module, and an output A capacitor, a first extended output capacitor discharge time module, and a second extended output capacitor discharge time module, wherein the control chip may include The output current setting pin, the drain pin, and the input voltage sensing pin. The voltage divider circuit can be connected between the output of the rectifier circuit and the reference ground. The output end of the voltage divider circuit can be connected to the input voltage sensing pin. The load module can be connected between the output of the rectifier circuit and the drain pin, the first end of the output capacitor can be connected to the output of the rectifier circuit, and the first extended output capacitor discharge time module can be connected to the second of the output capacitor Between the terminal and the drain pin, the second extended output capacitor discharge time module can be connected between the second end of the output capacitor and the output current setting pin, and wherein the input voltage sensing pin can be used to The output of the road is judged to enter the leading edge dimming mode, trailing edge dimming mode or non-dimming mode.

According to the LED driving circuit provided by the present embodiment, the first extended output capacitor discharge time module may include one or more diodes connected in series.

According to the LED driving circuit provided by the present embodiment, the second extended output capacitor discharge time module may include one or more diodes connected in series.

According to the LED driving circuit provided in this creative embodiment, the control chip may further include a high voltage sustain current input pin, and the value current control circuit may further include a current limiting module, which may be connected to the output of the rectifier circuit and the high voltage sustain current Between input pins.

According to the LED driving circuit provided by the present embodiment, the constant current control circuit may further include an output capacitor discharge cut-off module, and the load module may be connected to the output of the rectifier circuit via the output capacitor discharge cut-off module.

According to the LED driving circuit provided by the authoring embodiment, the constant current control circuit may further include a dummy load module, and the dummy load module may be connected in parallel at both ends of the load module.

According to the LED driving circuit provided by the present embodiment, the constant current control circuit may further include a current setting module, and the current setting module may be connected between the output current setting pin and the reference ground.

According to the LED driving circuit provided in this creative embodiment, the control chip may further include a working factor setting pin, and the constant current control circuit may further include an output capacitor discharging working factor setting module, and the output capacitor discharging working factor setting module may be connected to work The factor is set between the foot and the reference ground.

According to the LED driving circuit provided in this creative embodiment, the control chip may further include a closed loop compensation pin, and the constant current control circuit may further include a loop compensation module, and the loop compensation module may be connected to the closed loop compensation pin and Between the reference grounds.

According to the LED driving circuit provided in this creative embodiment, the control chip may further include a temperature reentry point setting pin, and the connection state of the temperature reentry point setting pin is one of the following items: connected to the reference ground, suspended, or through a or Multiple resistors connected in series are connected to the reference ground.

On the other hand, the authoring embodiment provides a control chip used in the LED driving circuit as described in the first aspect, the control chip may include an output current sampling sub-module, a constant current adjustment sub-module, a control transistor, an input Voltage sensing sub-module, pulse width modulation sub-module, and logic sub-module.

The input terminal of the output current sampling submodule can be connected to the output current setting pin, and the first input terminal of the constant current adjustment submodule can be connected to the first output terminal of the output current sampling submodule to control the gate of the transistor The pole can be connected to the output of the constant current regulator submodule, the drain of the control transistor can be connected to the drain pin, the source of the control transistor can be connected to the output current setting pin, and the input voltage senses the input of the submodule The terminal can be connected to the input voltage sensing pin, the input terminal of the pulse width modulation submodule can be connected to the working factor setting pin, and the output terminal of the pulse width modulation submodule can be connected to the second of the constant current adjustment submodule At the input end, the first input end of the logic sub-module can be connected to the output end of the input voltage sensing sub-module, and the first output end of the logic sub-module can be connected to the third input end of the constant current adjustment sub-module.

According to the control chip provided in this creative embodiment, it may further include a temperature reentry point setting pin and a temperature selection submodule, wherein the input terminal of the temperature selection submodule may be connected to the temperature reentry point setting pin, and the temperature selection submodule The output terminal can be connected to the second input terminal of the logic submodule.

The control chip provided according to the present embodiment may further include a high-voltage sustain current input pin and a sustain current control sub-module. The output end of the sustain current control sub-module may be connected to the high-voltage sustain current input pin to maintain the current control sub-module The first input can be connected to the input The second output terminal of the current sampling sub-module and the second input terminal of the sustain current control sub-module can be connected to the second output terminal of the logic sub-module.

The control chip provided according to this creative embodiment may further include a high-voltage power supply input pin and a low-dropout linear voltage regulator sub-module, wherein the low-dropout linear voltage regulator sub-module is connected to the high-voltage power supply input pin for controlling the chip For power supply.

Compared with the prior art, the LED driving circuit and the control chip provided by the embodiment of the present invention can realize an LED driving circuit without an inductive magnetic core device, realizing a small driving circuit, few system components, low cost, and meeting the actual application requirements of customers Wait.

110‧‧‧Rectifier circuit

120‧‧‧Constant current control circuit

1201, U1‧‧‧control chip

1202‧‧‧Voltage dividing circuit

1203‧‧‧load module

1204‧‧‧The first extended output capacitor discharge time module

1205‧‧‧Second extended output capacitor discharge time module

C1‧‧‧ Output capacitance

CC Regulator‧‧‧Constant current regulator sub-module

CS‧‧‧Output current setting pin

CS Sense‧‧‧Output current sampling submodule

COMP‧‧‧Closed loop compensation pin

D1, D2, D3, D4‧‧‧rectifier diode

D5, D6, D7 ‧‧‧ diode

Drain

DUTY‧‧‧Working factor setting pin

F1‧‧‧Fuse resistance

GND‧‧‧chip reference ground

HV‧‧‧High voltage power supply input pin

HVB‧‧‧High voltage sustain current input pin

Logic‧‧‧Logic submodule

PWM‧‧‧Pulse Width Modulation Submodule

R1, R2, R3, R4, R5, R6, R7

TH‧‧‧three temperature setting point

VS‧‧‧Input voltage sensing pin

VS Sense‧‧‧Input voltage sensing submodule

In order to more clearly explain the technical solution of the authoring embodiment, the following will briefly introduce the drawings required in the authoring embodiment. Obviously, the drawings described below are only some embodiments of the authoring. For those of ordinary skill in the art, without paying any creative labor, other drawings can also be obtained according to these drawings.

FIG. 1 shows a schematic structural diagram of an LED driving circuit provided by an embodiment of the present invention; FIG. 2 shows a schematic structural diagram of an LED driving circuit provided by another embodiment of the present invention; FIG. 3 shows a schematic structural diagram of a control chip provided by an embodiment of the present invention; FIG. 4 shows a schematic structural diagram of a control wafer provided by another embodiment of the present invention.

The features and exemplary embodiments of various aspects of the present creation will be described in detail below. In the following detailed description, many specific details are proposed in order to provide a comprehensive understanding of this creation. However, it is obvious to those skilled in the art that this creation can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of the creation by showing examples of the creation.

It should be noted that the embodiments in this creation and the features in the embodiments can be combined with each other without conflict. The embodiments will be described in detail below with reference to the drawings.

As an example, refer to FIG. 1, which shows an embodiment of the creation Schematic diagram of the structure of the provided LED driving circuit.

It should be understood that since LEDs are semiconductor devices with sensitive characteristics and negative temperature characteristics, they need to be stabilized and protected during application. Unlike ordinary incandescent bulbs, LEDs can be directly connected to 220V AC mains. The LED is driven by a low voltage constant current, and a circuit that meets the requirements must be designed to drive its normal operation.

In the embodiment shown in FIG. 1, the LED driving circuit may include a rectifier circuit 110 and a constant current control circuit 120, wherein the rectifier circuit 110 may be used to output direct current, and the constant current control circuit 120 may include a control chip 1201 The voltage circuit 1202, the load module 1203, the output capacitor C1, the first extended output capacitor discharge time module 1204, and the second extended output capacitor discharge time module 1205.

In some embodiments, the control chip 1201 may include an output current setting pin CS, a drain pin Drain, and an input voltage sensing pin VS. Among them, the drain pole is also called internal metal oxide semiconductor field effect transistor (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET) drain, which can be connected with the cathode of the LED lamp to a linear thyristor dimming constant current circuit.

As an example, referring to FIG. 1, the voltage divider circuit 1202 may be connected between the output of the rectifier circuit 110 and the reference ground, the output end of the voltage divider circuit 1202 may be connected to the input voltage sensing pin VS, and the load module 1203 It can be connected between the output of the rectifier circuit 110 and the drain pin Drain. The first end of the output capacitor C1 can be connected to the output of the rectifier circuit 110. The first extended output capacitor discharge time module 1204 can be connected to the first output capacitor C1. Between the second terminal and the drain pin Drain, the second extended output capacitor discharge time module 1205 can be connected between the second terminal of the output capacitor C1 and the output current setting pin CS.

The rectifier circuit 110 can rectify the alternating current input to obtain a DC voltage. The DC voltage can be divided by the voltage divider circuit 1202 to obtain a voltage division signal value, which can be input to the input voltage sense The measuring pin VS, and thus the input voltage sensing pin VS can be used to judge whether to enter the leading edge dimming mode, the trailing edge dimming mode or the non-dimming mode based on the output of the voltage dividing circuit.

And among them, for SCR dimming, SCR dimming mode can be divided into leading edge dimming mode and trailing edge dimming mode. Among them, when the SCR leading-edge phase-cut dimming mode starts phase-cutting, the input voltage is chopped at AC phase 0, and there is no voltage input until the thyristor is turned on. After the current edge dimming is triggered, It still needs to load the current for a period of time to maintain it in the on state. When this current is disconnected or weakened, the leading edge dimming mode is turned off. In addition, the SCR trailing edge phase-cut dimming mode turns on when starting from AC phase 0, turns off after a period of time, and maintains the off state until the end of the half cycle. After the zero point, repeat the same operation , Thereby changing the effective value of the alternating current.

In some embodiments, the rectifier circuit 110 may be a bridge rectifier circuit. The rectifier circuit is used to convert AC power into DC power. For example, the rectifier circuit 110 may include rectifier diodes D1, D2, D3, D4, and so on. In other embodiments, the rectification circuit may also be a full-wave rectification circuit, a half-wave rectification circuit, etc., which is not limited in this creation.

In some embodiments, the voltage divider circuit 1202 may include a plurality of resistors connected in series. In the series circuit, the circuits on each resistor are equal, and the sum of the voltages across each resistor is equal to the total voltage of the circuit. The voltage on each resistor Less than the total circuit voltage. In other embodiments, the voltage divider circuit may include a sliding varistor and the like. This authoring comparison is not limited, and the voltage dividing circuit 1202 can be any circuit that can realize the voltage dividing function.

In some embodiments, the load module 1203 may include LED light strings. As an example, the bulbs on the LED light string may be connected in parallel, and as another example, the bulbs on the LED light string may be connected in series. Moreover, the light bulb may be a direct insertion or a patch-type LED lamp.

In some embodiments, the load module 1203 may include LED light strings. As an example, the bulbs on the LED light string may be connected in parallel, and as another example, the bulbs on the LED light string may be connected in series. Moreover, the light bulb may be a direct insertion or a patch-type LED lamp.

In some embodiments, the second extended output capacitor discharge time module 1205 may include one or more diodes connected in series.

Through the above technical solution provided by the authoring embodiment, an inductive magnetic core device is not required, the driving circuit has a small size, and is in compliance with electromagnetic interference (Electromagnetic Interference, EMI) standards, and to a certain extent, achieve the technical effects of fewer system components, lower costs, and meet the actual application needs of users.

The following describes the LED driving circuit provided by another embodiment of the present invention in detail through a specific example. The example is only exemplary and is not intended to limit the present invention, as follows:

As an example, referring to FIG. 2, FIG. 2 shows a schematic structural diagram of an LED driving circuit provided by another embodiment of the present creation.

Specifically, as shown in FIG. 2, the LED driving circuit includes an electrically connected rectifier circuit 110 and a constant current control circuit 120.

In this embodiment, the rectifier circuit 110 may be a bridge rectifier circuit. The rectifier circuit is used to convert AC power into DC power. The rectifier circuit 110 includes a fuse resistor F1 and rectifier diodes D1, D2, D3, and D4.

Specifically, the input terminal of the rectifier circuit 110 is connected to alternating current, the first input terminal is connected to one end of the fuse resistor F1, the other end of the fuse resistor F1 is connected to the positive electrode of the rectifier diode D1, and the negative electrode of the rectifier diode D1 is connected To the negative electrode of the rectifier diode D2, the positive electrode of the rectifier diode D2 is connected to the negative electrode of the rectifier diode D4 and the second input terminal of the rectifier circuit 110, and the positive electrode of the rectifier diode D4 is connected to the rectifier diode D3 The positive electrode, the negative electrode of the rectifying diode D3 is connected to the positive electrode of the rectifying diode D1.

In addition, the first output terminal of the rectifier circuit 110 is connected to the negative electrode of the rectifier diode D1 and the negative electrode of the rectifier diode D2, and the second output terminal of the rectifier circuit 110 is connected to the positive electrode of the rectifier diode D3 and the rectifier diode The positive electrode and reference ground of D4.

It should be noted that, in other embodiments, the rectification circuit 110 may also be a full-wave rectification circuit, a half-wave rectification circuit, etc., which is not limited in this creation.

As an example, the constant current control circuit 120 may include a control chip U1, a voltage divider circuit 1202, a load module 1203, an output capacitor C1, a first extended output capacitor discharge time module 1204, and a second extended output capacitor discharge time module 1205, current limiting module, output capacitor discharge cut-off module, dummy load module, current setting module, output capacitor discharge working factor setting module, loop compensation module, and resistor R4.

In the embodiment shown in FIG. 2, the control chip U1 includes, in addition to the pins as described above, it may also include: a high-voltage power supply input pin HV, a high-voltage sustaining current input pin HVB, and a third gear temperature reentry point setting Pin TH, working factor setting pin DUTY, closed loop compensation pin COMP, chip reference ground GND, etc.

In the embodiment shown in FIG. 2, the voltage dividing circuit 1202 may include resistors R1 and R2. However, it should be noted that in other embodiments, the voltage divider circuit 1202 may include N voltage divider resistors connected in series, where N is an integer greater than 2. In yet another embodiment, sliding resistors can be used instead of resistors R1 and R2. There are no restrictions on this creation.

In the embodiment shown in FIG. 2, the load module may include LED light strings, such as a plurality of LEDs connected in series.

As an example, the first extended output capacitor discharge time module 1204 may include one or more diodes connected in series, and the diode is used to extend the discharge time of the output capacitor. For example, in the embodiment shown in FIG. 2, only one diode D6 is exemplarily shown to extend the discharge time of the output capacitor C1.

As an example, the constant current control circuit 120 may further include a second extended output capacitor discharge time module 1205, and the second extended output capacitor discharge time module 1205 may include one or more diodes connected in series, the diodes It can be used to extend the discharge time of the output capacitor. For example, in the embodiment shown in FIG. 2, only one diode D7 is exemplarily shown to extend the discharge time of the output capacitor C1.

As an example, the constant current control circuit 120 may further include a current limiting module, and the current limiting module may include one or more resistors connected in series. For example, in the embodiment shown in FIG. 2, only one resistor R3 is shown, and it is not intended to limit this creation.

As an example, the constant current control circuit 120 may further include an output capacitor discharge cut-off module, which may include one or more diodes connected in series. For example, in the embodiment shown in FIG. 2, only one diode D5 is shown. In other embodiments, the diode D5 may not be present.

As an example, the constant current control circuit 120 may further include a dummy load module, It may include one or more resistors connected in series. For example, in the embodiment shown in FIG. 2, only one resistor R7 is shown. There are no restrictions on this creation.

As an example, the constant current control circuit 120 may further include a current setting module, which may include one or more resistors connected in series. For example, in the embodiment shown in FIG. 2, only one resistor R5 is shown.

As an example, the constant current control circuit 120 may further include an output capacitor discharge working factor setting module, which may include one or more resistors connected in series. For example, in the embodiment shown in FIG. 2, only one resistor R6 is shown.

As an example, the constant current control circuit 120 may further include a loop compensation module, which may include one or more capacitors connected in series. For example, in the embodiment shown in FIG. 2, only one capacitor C2 is shown.

In some embodiments, the constant current control circuit 120 may further include one or more resistors connected in series between the pin TH and the second input terminal of the voltage divider circuit. For example, in the embodiment shown in FIG. 2, only one resistor R4 is shown. However, in other embodiments, the resistor R4 may not be present.

In the embodiment shown in FIG. 2, the first end of the resistor R1 (ie, the first input of the voltage divider circuit) is connected to the first output of the rectifier circuit, and the second end of the resistor R1 (ie, the divided The output terminal of the voltage circuit) is connected to the input voltage sensing pin VS, the first terminal of the resistor R2 (ie, the second input terminal of the voltage divider circuit) is connected to the second output terminal of the rectifier circuit, and the second terminal of the resistor R2 The terminal (ie, the output terminal of the voltage divider circuit) is connected to the second terminal of the resistor R1 and the input voltage sensing pin VS.

As an example, the first terminal of the current limiting resistor R3 may be connected to the first terminal of the resistor R1, and the second terminal of the current limiting resistor R3 may be connected to the high-voltage sustaining current input pin HVB.

As an example, the anode of the diode D5 may be connected to the first end of the current limiting resistor R3, and the cathode of the diode D5 may be connected to the high-voltage power supply input pin HV.

As an example, the positive pole of the LED light string may be connected to the negative pole of the diode D5 and the high-voltage power supply input pin HV, and the negative pole of the LED light string may be connected to the drain pole Drain. Among them, the diode D5 can be used to prevent the output capacitor C1 from discharging through the HVB.

As an example, the dummy load resistor R7 may be connected in parallel across the LED string. That is, the first end of the dummy load resistor R7 may be connected to the positive pole of the LED light string, and the second end of the dummy load resistor R7 may be connected to the negative pole of the LED light string.

As an example, the first end of the output capacitor C1 may be connected to the first end of the dummy load resistor R7, the second end of the output capacitor may be connected to the anode of the diode D6, and the cathode of the diode D6 may be connected to the drain Foot Drain. Among them, the diode D6 can be used to extend the discharge time of the output capacitor C1, and the resistor R7 can be used to prevent the discharge path from being provided.

In addition, when in the charging mode, the LED light string and the output capacitor C1 may be connected in parallel. When in discharge mode, the output capacitor C1 discharges the LED.

As an example, the second end of the output capacitor C1 may be connected to the negative electrode of the diode D7, and the positive electrode of the diode D7 may be connected to the output current setting pin CS. Among them, the diode D7 can be used to extend the discharge time of the output capacitor C1.

As an example, the first terminal of the resistor R5 may be connected to the output current setting pin CS, and the second terminal of the resistor R5 may be connected to the first terminal of the resistor R2 and the second output terminal of the rectifier circuit. Among them, R5 can be used to set the average current value of the output LED string.

As an example, the first terminal of the resistor R6 may be connected to the duty factor setting pin DUTY, and the second terminal of the resistor R6 may be connected to the first terminal of the resistor R2 and the second output terminal of the rectifier circuit. Among them, the resistor R6 can be used to set the discharge working factor of the output capacitor C1.

As an example, the first terminal of the capacitor C2 may be connected to the closed-loop compensation pin COMP, and the second terminal of the capacitor C2 may be connected to the first terminal of the resistor R2, the second output terminal of the rectifier circuit, and the second terminal of the resistor R5 And the second end of resistor R6. Among them, the capacitor C2 can be used for internal loop compensation.

As an example, the first end of the resistor R4 may be connected to the third-grade temperature reentry point setting pin TH, and the second end of the resistor R4 may be connected to the second output end of the rectifier circuit. In other embodiments, the resistor R4 may not be provided.

Referring to FIG. 3, FIG. 3 shows a schematic structural diagram of a control chip U1 provided by an embodiment of the present invention.

As an example, the control chip U1 may include an output current sampling submodule CS Sense, a constant current regulator submodule CC Regulator, a control transistor, an input voltage sensing submodule VS Sense, and a pulse width modulation submodule (Pulse Width Modulation (PWM), logic sub-module Logic.

As an example, the average voltage on the CS pin can be sampled by the output current sampling sub-module, and the sampled signal can be transmitted to the constant current regulating sub-module, so that the constant current regulating sub-module generates a control signal to control the power The gate voltage of the transistor (ie, the control transistor) adjusts the output current value so that the average value of the output current meets the design value.

The input terminal of the output current sampling submodule can be connected to the output current setting pin CS, and the first input terminal of the constant current adjustment submodule can be connected to the first output terminal of the output current sampling submodule to control the The gate can be connected to the output of the constant current regulator submodule, the drain of the control transistor can be connected to the drain pin, the source of the control transistor can be connected to the output current setting pin CS, and the input voltage sensing submodule Can be connected to the input voltage sensing pin VS, the PWM input can be connected to the duty factor setting pin Duty, the PWM output can be connected to the second input of the constant current regulation sub-module, the logic sub-module The first input terminal may be connected to the output terminal of the input voltage sensing submodule, and the first output terminal of the logic submodule may be connected to the third input terminal of the constant current regulation submodule.

Wherein, in some embodiments, the duty factor setting pin Duty can be connected to a resistor (for example, resistor R6) to the chip reference ground for the duty factor when the output capacitor C1 is discharged.

Among them, the rectified DC voltage is divided by a voltage dividing circuit (for example, a voltage dividing circuit composed of resistors R1 and R2) to obtain a voltage dividing signal value, and the voltage dividing signal value is transmitted to the input through the VS pin The voltage sensing sub-module, and then after a series of processing of the input voltage sensing sub-module, obtain a digital signal carrying VS information, and input the digital signal into the logic sub-module, which is then used to judge the entry into the leading edge Light mode, trailing edge dimming mode, or non-dimming mode.

And among them, different discharge frequency working factors can be set through external resistors (for example, R6), which are input into the PWM control module through the working factor setting pin Duty, and PWM signals with different working factors can be generated. For example, when CS is low, the PWM signal The constant current regulating sub-module directly controls the transistor and supplies power to the load module through the output capacitor C1.

As an example, the average voltage on the CS pin is sampled by the output current sampling sub-module circuit to obtain a sampling signal, and the sampling signal is subjected to a series of processing and then passed to the constant current regulating sub-module to generate a control signal. The control signal controls the gate voltage value of the power transistor, thereby adjusting the output current value so that the average value of the output current meets the design value.

As an example, the rectifier circuit receives the AC voltage, obtains the DC voltage after conversion, and inputs the DC voltage into the voltage divider circuit, for example, divides the DC voltage through resistors R1 and R2 to obtain the voltage-divided signal value, which is transmitted to the input through the VS pin The voltage sensing sub-module, after being processed by the input voltage sensing sub-module, generates a digital signal carrying VS information, and transmits the digital signal to the logic sub-module, which can be used to judge whether to enter the leading edge dimming mode or the trailing edge Dimming mode or non-dimming mode.

It should be noted that the thyristor dimming can be used to adjust the current or voltage of the power supply, so that the LED string as a load can produce light output of different intensities.

For example, there are multiple LED dimming methods: linear dimming, thyristor dimming, pulse width dimming, etc.

Specifically, for thyristor dimming, the thyristor dimming mode can be divided into a leading edge dimming mode and a trailing edge dimming mode. Among them, when the SCR leading-edge phase-cut dimming mode starts phase-cutting, the input voltage is chopped at AC phase 0, and there is no voltage input until the thyristor is turned on. After the current edge dimming is triggered, It still needs to load the current for a period of time to maintain it in the on state. When this current is disconnected or weakened, the leading edge dimming mode is turned off. In addition, the SCR trailing edge phase-cut dimming mode turns on when starting from AC phase 0, turns off after a period of time, and maintains the off state until the end of the half cycle. After the zero point, repeat the same operation , Thereby changing the effective value of the alternating current.

The specific structure of the control wafer U1 provided by the embodiment of the present invention will be described in detail below through specific examples. For example, refer to FIG. 4, which shows a schematic structural diagram of the control wafer U1 provided by another embodiment of the present invention.

In some embodiments, in addition to the various parts included in the control chip U1 as described in the foregoing embodiments, the control chip U1 may further include a temperature reentry point setting pin TH and a temperature selection submodule.

The input terminal of the temperature selection sub-module can be connected to the temperature foldback point setting pin TH, and the output terminal of the temperature selection sub-module can be connected to the second input terminal of the logic sub-module.

In addition, it should be noted that the third-threshold temperature turning point setting pin TH can be suspended, can be connected to the reference ground, and can be connected to the reference ground through one or more series-connected resistors. And among them, the grounding first-grade temperature turning point, the second-grade temperature turning point is suspended, and the third-grade temperature turning point of a certain resistance value is connected.

Wherein, a current is output from the TH pin, and the current generates a different voltage on one or more resistors (eg, resistor R4) connected to the TH pin, and the voltage is input into the temperature selection sub-module, and the temperature selection sub-module Judging the generated voltage value, generating a third gear temperature turning point signal and inputting it to the logic sub-module, so as to realize the third gear temperature turning point temperature set by the control chip U1.

In some embodiments, in addition to the various parts included in the control chip U1 as described in the foregoing embodiments, the control chip U1 may further include a high-voltage sustain current input pin HVB and a sustain current control sub-module.

The output terminal of the sustain current control sub-module can be connected to the high-voltage sustain current input pin, and the first input terminal of the sustain current control sub-module can be connected to the second output terminal of the output current sampling sub-module to maintain the current control sub The second input terminal of the module can be connected to the second output terminal of the logic submodule.

It should be noted that the high-voltage sustain current input pin HVB can be used to provide the sustain current required by the dimmer for dimming. Among them, the dimmer is an electrical device that changes the luminous flux of the light source in the lighting device and adjusts the illuminance level, and its purpose is to adjust the different brightness of the light.

In addition, the rectified high voltage is connected in series with one or more series-connected resistors (for example, R3), through the high-voltage sustaining current input pin HVB, into the sustaining current control submodule, leading edge dimmer and trailing edge dimming are generated Different sustain current control required by the controller.

In some embodiments, in addition to the various parts included in the control chip U1 as described in the foregoing embodiments, the control chip U1 may further include: a high-voltage power supply input pin HV and a low-dropout linear regulator submodule (Low Dropout Regulator, LDO), whose input terminal is connected to the high-voltage power supply input pin HV, the low-dropout linear regulator sub-module can be used to power the control chip, for example, to supply power to at least one of the following items: output current sampling sub-module Group, constant current adjustment submodule, input voltage sensing submodule, pulse width modulation submodule, logic submodule, temperature selection submodule, and maintenance current control submodule.

Among them, the high-voltage power supply input pin HV can be used to power the control chip U1, for example, power supply for one or more sub-modules in the control chip, such as output current sampling sub-module, maintenance current control sub-module, constant current Regulation submodule, input voltage sensing submodule, logic submodule, and temperature selection submodule.

In addition, the alternating current enters the rectifier circuit to obtain a DC voltage, and the rectified high voltage is input to the HV pin of the control chip, and then input to the LDO sub-module and stabilizes it, so that it is one or more sub-modules inside the control chip U1 For power supply.

In some embodiments, in addition to the various parts included in the control chip U1 as described in the foregoing embodiments, the control chip U1 may further include: a closed loop compensation pin COMP, which is connected to the constant current regulation The fourth input terminal of the submodule.

Among them, the closed loop compensation pin COMP can be used to compensate the loop of the constant current adjustment submodule to ensure that the linear constant current (Line CC) and the load constant current (Load CC) are in closed loop control.

Each part of this specification is described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

The above is only the specific implementation of this creation, but the scope of protection of this creation is not limited to this, any person skilled in the art can easily think of various equivalent modifications within the technical scope disclosed by this creation Or replacement, these modifications or replacements should be covered within the scope of protection of this creation. Therefore, the protection scope of this creation shall be subject to the protection scope of the patent application scope.

110‧‧‧Rectifier circuit

120‧‧‧Constant current control circuit

1201‧‧‧Control chip

1202‧‧‧Voltage dividing circuit

1203‧‧‧load module

1204‧‧‧The first extended output capacitor discharge time module

1205‧‧‧Second extended output capacitor discharge time module

C1‧‧‧ Output capacitance

CS‧‧‧Output current setting pin

Drain

GND‧‧‧chip reference ground

VS‧‧‧Input voltage sensing pin

Claims (14)

An LED drive circuit is characterized by comprising: a rectifier circuit for outputting direct current; a constant current control circuit, including: a control chip, including an output current setting pin, a drain pin, an input voltage sensing pin; a voltage divider circuit, The voltage divider circuit is connected between the output of the rectifier circuit and the reference ground, the output end of the voltage divider circuit is connected to the input voltage sensing pin; the load module, the load module is connected at Between the output of the rectifier circuit and the drain pin; the output capacitor, the first end of the output capacitor is connected to the output of the rectifier circuit; the first extended output capacitor discharge time module, the first extended An output capacitor discharge time module is connected between the second end of the output capacitor and the drain pin; a second extended output capacitor discharge time module, the second extended output capacitor discharge time module is connected to the Between the second end of the output capacitor and the output current setting pin; wherein the input voltage sensing pin is used to determine whether to enter the leading edge dimming mode, trailing edge dimming mode or based on the output of the voltage divider circuit Non-dimming mode. The LED driving circuit according to item 1 of the patent application scope, wherein the first extended output capacitor discharge time module includes one or more diodes connected in series. The LED drive circuit according to item 1 of the patent application scope, wherein the second extended output capacitor discharge time module includes one or more diodes connected in series. The LED driving circuit according to item 1 of the patent application scope, wherein the control chip further includes a high-voltage sustaining current input pin, and the constant current control circuit further includes: a current limiting module connected to the current limiting module Between the output of the rectifier circuit and the input pin of the high-voltage sustaining current. The LED drive circuit according to item 1 of the patent application scope, wherein the constant current control circuit further includes an output capacitor discharge cut-off module, and The load module is connected to the output of the rectifier circuit through the output capacitor discharge cut-off module. The LED drive circuit according to item 1 of the patent application scope, wherein the constant current control circuit further includes: a dummy load module, and the dummy load module is connected in parallel at both ends of the load module. The LED drive circuit according to item 1 of the patent application scope, wherein the constant current control circuit further includes: a current setting module connected to the output current setting pin and the reference ground between. The LED drive circuit according to item 1 of the patent application range, wherein the control chip further includes an operating factor setting pin, and the constant current control circuit further includes: an output capacitor discharge operating factor setting module, the output capacitor The discharge working factor setting module is connected between the working factor setting foot and the reference ground. The LED drive circuit according to item 1 of the patent application scope, wherein the control chip further includes a closed-loop compensation pin, and the constant current control circuit further includes: a loop compensation module, the loop compensation module The group is connected between the closed-loop compensation foot and the reference ground. The LED drive circuit according to item 1 of the patent application scope, wherein the control chip further includes a temperature reentry point setting foot, and the connection state of the temperature reentry point setting foot is one of the following items: connected to all The reference ground, floating, or connected to the reference ground through one or more series-connected resistors. A control chip used in the LED driving circuit according to any one of items 1 to 10 of the patent application range, wherein the control chip includes: an output current sampling sub-module, and the output current sampling sub-module The input end of the module is connected to the output current setting pin; the constant current adjustment sub-module, the first input end of the constant current adjustment sub-module is connected to the output The first output terminal of the current sampling submodule; the control transistor, the gate electrode of the control transistor is connected to the output terminal of the constant current regulating submodule, and the drain electrode of the control transistor is connected to the drain Pole pin, the source of the control transistor is connected to the output current setting pin; input voltage sensing sub-module, the input end of the input voltage sensing sub-module is connected to the input voltage sensing pin; A pulse width modulation sub-module, the input end of the pulse width modulation sub-module is connected to the working factor setting pin, and the output end of the pulse width modulation sub-module is connected to the second of the constant current adjustment sub-module Input terminal; logic submodule, the first input terminal of the logic submodule is connected to the output terminal of the input voltage sensing submodule, the first output terminal of the logic submodule is connected to the constant The third input terminal of the flow regulating submodule. The control chip according to item 11 of the patent application scope, further comprising: a temperature reentry point setting pin; a temperature selection submodule, the input end of the temperature selection submodule is connected to the temperature reentry point setting pin, The output terminal of the temperature selection sub-module is connected to the second input terminal of the logic sub-module. The control chip according to item 11 of the patent application scope, further comprising: a high-voltage sustain current input pin; a sustain current control sub-module, the output end of the sustain current control sub-module is connected to the high-voltage sustain current input Pin, the first input of the sustaining current control sub-module is connected to the second output of the output current sampling sub-module, and the second input of the sustaining current control sub-module is connected to the logic sub The second output of the module. The control chip according to item 11 of the patent application scope, which further includes: a high-voltage power supply input pin; a low-dropout linear regulator submodule, the low-dropout linear regulator submodule is connected to the high-voltage power supply input pin , Used to power the control chip.

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