CN104853474A - Direct LED Driver - Google Patents

Abstract

The invention relates to a direct type light-emitting diode driving device, which comprises a main LED lamp string comprising a plurality of LED units which are connected in series, a secondary LED lamp string group comprising a plurality of secondary LED lamp strings which are connected in series with each other and are connected in series with the main LED lamp string, and a pre-adjusting element. A direct driver connected to each of the secondary LED strings has a current source for selectively turning off selected ones of the secondary LED strings.

Description

Direct LED Driver

technical field

The invention relates to a device for driving an LED driver, in particular to a direct type LED driver.

Background technique

Generally, there are two types of common light emitting diode (LED) drive circuits, one is a switch drive circuit (switch drive), and the other is a direct drive circuit (direct driver). Switching driving circuits use a magnetic element (eg, an inducer) to store power from a power supply and directly deliver the power to an LEC string. The disadvantages of the switchable drive circuit are that an additional electromagnetic filter (EMI Filter) needs to be installed, more components need to be installed, and there will be obvious output current ripple (Output Current Ripple), but there is no large capacitance.

The direct drive circuit can achieve an efficiency as high as 99%, requires fewer components, and is relatively low in cost. However, the output current ripple of the direct drive circuit is obviously related to the power factor. To put it simply, if the power factor is corrected effectively, a direct drive circuit with almost no output current ripple can be designed.

Therefore, it is necessary to develop an LED driver that can drive lamps with high efficiency under various input voltages, has low harmonic distortion (harmonic distortion, HD) characteristics, high power filter factor and low output current ripple. Devices are very important.

Contents of the invention

According to the above-mentioned requirements, an object of the present invention is to provide a direct light-emitting diode driving device, which includes a main LED light string, a secondary LED light string group, a preset device, a power factor correction module and A direct drive.

The main LED light string includes a plurality of LED units connected in series, and has a first end and a second end. The secondary LED light string group has a first end and a second end, and includes a plurality of secondary LED light strings connected in series, the first end of the secondary LED light string group is connected to the primary LED light string second end. The pre-regulator includes a diode rectifier connected to a power source to convert an AC input voltage of the power source into a pulsed DC voltage. The power factor correction module is connected between the diode rectifier and the first end of the main LED light string, and adjusts the pulsed DC voltage to a stable output voltage, wherein the stable voltage is output to drive The primary LED light string, the secondary LED light string group or drive the primary LED light string and the secondary LED light string group. The direct driver has a current source connected to each secondary LED light string to selectively turn off the selected secondary LED light string.

In one embodiment, a communication path is further included between the preset element and the direct driver.

In one embodiment, the direct driver further includes:

a current feedback path connected to a controller of the preset element; and

A current feedback module is used to generate a control voltage to the controller of the preset device through the current feedback path to regulate the output stable voltage.

In one embodiment, the current feedback module further includes an integrating circuit and a current channel, the integrating circuit is connected between the secondary LED light string group and the current source, the current channel is connected to the integrating circuit, and an indirect diodes to selectively regulate the current flowing into the current source. The current feedback path further includes a first resistor, a second resistor and a third resistor. The second resistor is connected in series with the first resistor of the current feedback path, and a junction of the first resistor and the second resistor is connected to an internal comparator inside the controller, and the internal comparator has an internal reference voltage. The third resistor has a first end and a second end, the first end is connected to a junction of the first resistor and the second resistor, and the second end is connected to the current channel.

In one embodiment, the comparator is composed of an operational amplifier with a reference voltage, and the current channel is an inverter, which supplies current when the voltage of the current source is higher than the reference voltage.

In one embodiment, the integrating circuit consists of a transfer conductance driving a comparator, and the current channel is a buffer.

In one embodiment, the preset element is coupled to a plurality of direct drives.

In one embodiment, each direct driver has a current feedback module, which makes current flow out from the current feedback path, and the flowing current generates a control voltage.

In one embodiment, the current feedback path further includes a first resistor, a second resistor and a third resistor. The second resistor is connected in series with the first resistor, and a junction of the first resistor and the second resistor is connected to an internal comparator inside the controller, and the internal comparator has an internal reference voltage. The third resistor has a first end connected to a junction of the first resistor and the second resistor.

In one embodiment, the direct light emitting diode driving device further includes a protective diode, which is arranged between the third resistor and the current channel, and allows the current to flow from the junction of the first resistor and the second resistor to the preset element .

In one embodiment, the direct light-emitting diode driving device includes a current sensing resistor, which senses a current corresponding to the voltage of the main LED light string to which the secondary LED light string is attached, an internal current source, and has a preset current, when the preset current is equal to the minimum voltage value of the regulated output voltage, the current value sensed by the current sensing resistor, a conduction diode, and a first resistor, when the current value sensed by the current sensing resistor is high At the current value preset by the internal current source, the first resistor allows excess current to flow into the steering diode, an error amplifier with a reference voltage source, and a NOMS transistor connected to the error amplifier to form The current source, an offset resistor, and a REST resistor are connected to the conduction diode, and generate a bias voltage between the reference voltage source and the REST resistor, wherein the bias voltage reduces the current flowing into the LED light string.

In one embodiment, the current sensing resistor is connected to the first end of the main LED light string and the preset element, and the first resistor has a first end, a second end and a third end, wherein the first end It is connected to the current sensing resistor, and the second end is connected to the second end of the secondary LED light string group, the internal current source is connected to the third end of the first resistor, and the current-steering diode has an anode and an a cathode, wherein the anode is connected to the third terminal of the first resistor, an error amplifier having a positive input terminal, a negative input terminal and an output terminal, wherein the positive input terminal is connected to a reference voltage source, and the negative input terminal It is connected to the cathode of the conduction diode, and the NMOS transistor has a first end, a second end and a third end, wherein the first end is connected to the second end of the secondary LED light string group, and the second end The terminal is connected to the first output terminal of the error amplifier, the third terminal is connected to the REST resistor, and the deviation resistor is connected between the negative output terminal of the error amplifier and the REST resistor.

Therefore, the driving device of the present invention is intended to solve the problems encountered by current LED drivers. The pre-adjustment element can supply various output voltages in different ranges, and has the characteristics of high power factor and low harmonic distortion. In addition, the pre-adjustment element It is only necessary to provide a stable regulated output voltage, so that the power can be stably supplied to the LED driver, so that the LED driver can provide a stable voltage output without output voltage ripple.

Description of drawings

FIG. 1 is a schematic diagram illustrating the structure of a direct LED driving circuit according to an embodiment of the present invention.

FIG. 2 illustrates the circuit structure of the direct LED driving device in FIG. 1 .

FIG. 3 is a structure diagram of another embodiment of the present invention.

FIG. 4 is a structure diagram of another embodiment of the present invention.

FIG. 5 is a block diagram illustrating yet another embodiment of the present invention.

FIG. 6 illustrates an embodiment of the present invention in which a single preset element is used to drive a plurality of direct LED driving devices arranged in parallel with each other.

FIG. 7 illustrates an embodiment of a direct LED driving circuit.

【Symbol Description】

10 main LED string lights

20 Secondary LED String Light Groups

200 Secondary LED String Lights

30 preset elements

301 diode rectifier

302 power factor correction module

3021 first capacitor

3022 inductor

3023 Controller

30231 internal comparator

3024 Switching Transistor

3025 diode

3026 second capacitor

40 direct drive

401 current source

50 connected paths

60 current feedback module

61 integrating circuit

62 current channels

63 Current Feedback Path

70 Current feedback module

71 Integrator circuit

72 current channels

73 Current Feedback Path

80 Ω current sense resistor

81 first transistor

82 internal current source

83 Steering diode

84 error amplifier

85 MONS Transistor

86 offset resistors

87 REST resistance

D indirect diode

D1 protection diode

R1 first resistor

R2 second resistor

R3 third resistor

Detailed ways

The device or method of the present invention is described below only with examples. The following descriptions of the embodiments are descriptions of the technical features of the present application.

Please refer to FIG. 1 . FIG. 1 is a schematic diagram illustrating the structure of a direct LED driving device according to an embodiment of the present invention. In this embodiment, the direct LED driving device includes a main LED lamp string 10 , a secondary LED lamp string group 20 , a preset device 30 and a direct driver 40 . Wherein, the main LED light string 10 includes a plurality of LED units connected in series, and has a first end and a second end. The secondary LED light string group 20 has a first end and a second end, and includes a plurality of secondary LED light strings 200 connected in series. The first end of the secondary LED light string group 20 is connected to the main LED light At the second end of the string 10, each secondary LED light string 200 includes at least one LED unit.

The preset device 30 includes a diode rectifier 301 and a power factor correction module 302 . Wherein, the diode rectifier 301 is connected to a power source, and converts the AC input voltage from the power source into a pulsed DC voltage. The power factor correction module 302 is disposed between the diode rectifier 301 and the first end of the main LED light string 10, and adjusts the pulsed DC voltage to a stable regulated output voltage. Moreover, the preset element 30 can supply various ranges of input voltages with high power factor and low harmonic distortion characteristics. It should be noted that the pre-regulator 301 does not need to provide a regulated input current, as long as it provides a stable and regulated output voltage with a small but reasonable current ripple.

In an embodiment of the present invention, the preset device 30 may have a boost-mode quasi-resonant structure. The pre-regulator 301 with boost quasi-resonant structure can be applied in a boundary mode situation, and it is also the simplest application method. The wave front of the output voltage regulated by the pre-adjustment element 30 should fall at the maximum wave front position of the AC input voltage of the power supply. Those skilled in the art can easily know that the components with boost mode can only provide an output voltage equal to or higher than the AC input voltage.

Please refer to FIG. 2 , which illustrates the circuit structure of the direct LED driving device in FIG. 1 . The diode rectifier 301 in the preset element 30 is formed by four diodes. The power factor correction module 302 includes a first capacitor 3021 , an inductor 3022 , a controller 3023 , a switching transistor 3024 , a diode 3025 , and a second capacitor 3026 . Wherein, the first capacitor 3021 is connected in parallel to the diode rectifier 301 and has a first terminal and a second terminal. The inductor 3022 has a first terminal and a second terminal. The first terminal of the switching transistor 3024 is connected to the second terminal of the inductor, and the second terminal of the switching transistor 3024 is connected to the controller 3023 . The second capacitor 3026 has a first terminal and a second terminal. The diode 3025 is disposed between the first terminal of the switching transistor 3024 and the first terminal of the second capacitor 3026 . The second terminals of the first capacitor 3021 and the second capacitor 3026, and the third terminal of the switching transistor 3024 are connected to a common ground.

The direct driver 40 includes a current source 401 connected to each secondary LED light string 200 . The direct driver 40 selectively turns off selected secondary LED light strings 200 to ensure maximum LED driving efficiency. The current source 401 is disposed between the second end of the secondary LED lamp string group 20 and the power factor correction module 302 of the preset device 30 . The direct driver 40 (and the accompanying primary LED light string 10 and secondary LED light string groups 20) have a preset operating voltage range that covers both the expected maximum output voltage and the expected minimum output voltage of the preset element 30. The output voltage should also cover the output voltage range regulated by the pre-regulator 30, as well as the LED voltage variation due to temperature, diode lifetime and operating variables.

The direct driver 40 monitors the voltage across the entire main LED light string 10 and the secondary LED light string group 20 and adjusts the current accordingly so that the overall output power of the main LED light string 10 and the secondary LED light string group 20 maintains is a constant.

As shown in FIG. 2 , the direct LED driving device of the present invention further includes a communicating path 50 disposed between the presetting element 30 and the direct driver 40 . When the effective power range of the direct driver 40 is increased, the number of secondary LED light strings 200 can be reduced. For example, when the temperature rises and the voltage flowing to the main LED light string 10 becomes very small, the secondary LED light string group 20 can be connected in series with the main LED light string 10 . If the secondary LED light string group 20 lacks enough secondary LED light strings 200 to counteract the voltage flowing to the LEDs, the voltage flowing through the current source 401 of the direct driver 40 will increase, and the overall power supply efficiency will decrease. Therefore, once the controller 3023 in the pre-regulator 30 can sense the voltage flowing through the main LED light string 10 and the secondary LED light string group 20 through the communication path 50, the pre-regulator 30 can reduce the regulation of the output. Voltage, and make the direct driver 40 can exert the greatest working efficiency. In addition, in order to sense the voltage flowing through the main LED light string 10 and the secondary LED light string group 20 through the communication path 50, and adjust the overall brightness of the main LED light string 10 and the secondary LED light string group 20, the preset The element 30 controls the current source 401 of the direct driver 40 to maintain a stable light output.

Conversely, assuming that the temperature of the main LED light string 10 and the secondary LED light string group 20 decreases, the voltage supplied to the main LED light string 10 and the secondary LED light string group 20 becomes more required than usual. The direct driver 40 can gradually remove the voltage supplied to the secondary LED light string groups 20 from the primary LED light string 10 until all the secondary LED light string groups 20 are turned off. The direct driver 40 will reduce the output of the regulation voltage of the pre-regulator 30 so that the device can maintain the best operating efficiency.

The communication between the presetting element 30 and the direct driver 40 can be in the form of digital, analog voltage or current. In order to avoid “talking” back and forth between two values when the number of secondary LED light strings 200 is close to a critical value (that is, the maximum expected voltage or the minimum expected voltage of the preset element 30 has been reached), Therefore, it is necessary to add a hysteresis in a control method of the controller 3023 of the presetting element 30 .

Because the action of the presetting element 30 has only one single step, the overall working efficiency can exceed 97%. If the direct driver 40 connected to the pre-adjustment element 30 can reach more than 98%, then according to the combination of the pre-adjustment element 30 and the direct driver 40 disclosed in the present invention, its effective power supply efficiency can reach 95% (97%×98%) , such power supply efficiency is excellent, and it is very important for those high power systems (high power systems) where a 10% reduction in efficiency will cause a lot of power waste or heat loss.

Please refer to FIG. 3, which is a structural diagram of another embodiment of the present invention? The advantages of the driving device disclosed in the present invention are more prominent because the efficiency reduction of the high power supply system will cause power waste or heat loss. In this embodiment, a single presetting element 30 is connected to a plurality of direct drivers 40 , and since the cost of the direct drivers 40 is relatively cheap, the cost of the device will not be excessively increased. When the power supply is increased, it may be necessary to increase the size of the preset element 30, but even if the power supply is doubled, the volume and cost of the preset element 30 will not be higher than twice the original, so the output voltage The cost can still be maintained at a low price.

Please refer to FIG. 4 , which is a structural diagram illustrating another embodiment of the present invention. The difference between this embodiment and FIG. 3 is that the controller 3023 of the pre-adjustment element 30 of this embodiment does not use a hysteresis control method. In this embodiment, the LED direct driving device further includes a current feedback module 60 and a current feedback path 63 connected to an internal comparator 30231 in the controller 3023 of the preset device 30 . The internal comparator 30231 has an internal reference voltage (Vrc). The current feedback module 60 is used to adjust the output voltage (Vout) regulated by the controller 3023 and includes an integrator 61 and a current passenger 62 . The current feedback path 63 includes a first resistor R1, a second resistor R2, and a third resistor R3. The integrating circuit 61 is connected between the secondary LED light string group 20 and the current source 401 . The current channel 62 is connected between the integration circuit 61 and the third resistor R3, and selectively increases or decreases the current supply according to a value of a control voltage (Vadj) generated by an indirect diode D. The first resistor R1 and the second resistor R2 are connected in series with each other, and then connected in parallel to the second capacitor 3026 . The first end of the third resistor R3 is connected to a junction of the first resistor R1 and the second resistor R2. In such a connection mode, an additional current can be injected into the junction between the first resistor R1 and the second resistor R2 through the third resistor R3, and the relationship between the regulated output voltage (Vout) and the control voltage (Vadj) It can be expressed by the following equation:

Vout=[(Vrc×R2×R3/R1)+(R3×Vrc)+(R2×Vrc)−(R2×Vadj)]/R3.

In the embodiment disclosed in FIG. 4 , the integration circuit 61 is embedded in an operational amplifier (Operational Amplifier, op-Amp) and has a comparison voltage (Vr). The current channel 62 is a unidirectional inverter (inverter), because the current channel 62 only allows the current to be introduced into the third resistor R3 to regulate the reduction of the output voltage (Vout), and considering the relationship between R1/R2, the regulated The output voltage cannot be higher than its internal voltage value.

During the operation, if the average voltage value passing through the current source 401 is lower than the reference voltage (Vr), the output of the integration circuit 61 is adjusted to increase, and the output of the current channel 62 with a unidirectional inverter structure is adjusted to decrease, And the current channel 62 will be locked and unable to operate. Once the average voltage across the current source 401 increases and is higher than the reference voltage (Vr), the output of the current channel 62 starts to decrease. When the voltage of the power supply flow 401 is lower than an intermediate resistance value, the current channel 62 will start to supply current so that the regulated output voltage (Vout) of the preset device 30 is reduced. The intermediate resistance value is defined as the distance between the first resistor R1 and the second resistor R2 The resistor value is affected by the reference voltage (Vrc) of the internal comparator 30231 in the controller 3023. In many commercially available controllers, the internal parameter of the reference voltage (Vrc) of the internal comparator 30231 in the controller 3023 is approximately 2.5 volts.

Please refer to FIG. 5 , which is a structural diagram illustrating another embodiment of the present invention. In this embodiment, the integration circuit 61 is embedded in a transconductance structure, that is, composed of a transfer conductance driving a comparator, and the current channel 62 has a buffer function. This embodiment is the same as the embodiment of FIG. 4 in that the current channel 62 can only supply current according to the ratio of R1/R2, regardless of whether it is an inverter structure or a buffer structure, so that the output voltage gradually decreases from the maximum value. .

Usually, in general operation, the LED unit will heat up and the voltage flowing through the LED unit will decrease, which will lead to an increase in the voltage passing through the current source, resulting in a decrease in power supply efficiency and an increase in waste heat generated by the lamp tube. Therefore, through the present invention The current feedback module 60 in the embodiment of FIG. 4 or FIG. 5 can sense the voltage increase of the current source 401 and respond to decrease the output voltage (Vout). Like adjusting the output voltage, the voltage passing through the current source 401 will also decrease, so as to achieve the effect of increasing power supply efficiency and reducing waste heat generation.

The embodiment shown in FIG. 4 or FIG. 5 demonstrates the excellent efficacy of the present invention, especially for a lamp using analog dimming. In the process of analog dimming, when the dimming is the brightest, the current through the LED will be reduced to a relatively small value, so the voltage flowing through each LED unit in the LED light string will be higher than the current through the LED full load. The time is much lower, so it can produce higher operating efficiency when performing analog dimming.

In another similar state, if an overheating protection mechanism is applied to an LED module so as to reduce the current flowing through the LED in an overheating state, the output voltage regulated by the preset element 30 will also flow through the LED The voltage drops and decreases. This ensures that the (LED?) device does not have to contend with a rise in operating voltage during overheating operation.

In addition, when a single preset element 30 is used to drive a plurality of direct LED driving devices arranged in parallel with each other, it is necessary to make some modifications to FIG. 4 or FIG. 5 . Because in such a situation, the required control voltage (Vadj) should be kept at the lowest voltage state, not the highest voltage state mentioned in the preceding paragraph.

In order to solve this problem and maintain an absolute maximum output voltage under safety considerations, please refer to Figure 6. Figure 6 is a description of the direct LED driver that uses a single pre-adjustment element to drive multiple parallel arrangements of the present invention. Embodiment of the device. Each direct LED driving device (not shown in the figure) is connected to a current feedback module 70 , and the current feedback module 70 is very similar to the current feedback module 60 described in FIG. 4 or FIG. 5 . Each current feedback module 70 includes an integrating circuit 71 and a current channel 72 connected in series with the integrating circuit 71. The difference between FIG. 6 and FIG. 4 or FIG. 5 is that the direction of the indirect diode D in the current channel 72 is opposite. Yes, in such a state, the reverse indirect diode D in the current channel 72 can only lead out the current. That is, the current channel 62 in FIG. 4 or FIG. 5 is used to increase the current, and the current channel 72 in this embodiment is used to decrease the current.

When all the current channels 72 are connected together, the lowest output voltage of the current channels 72 is determined as a control voltage (Vadj). Because the output voltage of the current channel 72 is the minimum, when the current flows back to the preset element 30, the output voltage regulated by the preset element 30 is sufficient to supply the main LED light string 10 and the secondary LED light string group 20 with sufficient voltage to maintain required current.

In this embodiment, the current feedback path 73 (without antecedent) further includes a securing diode D1. The protection diode D1 is disposed between the third resistor R3 and the current channel 72 and has an anode and a cathode. The anode of the protection diode D1 is connected to the third resistor R3 , and the cathode is connected to the current channel 72 . The protection diode D1 is only capable of allowing the current to move from the junction of the first resistor R1 and the second resistor R2 to the preset element 30, so as to ensure that the regulated output voltage will not exceed the ratio of R1/R2.

Please refer to FIG. 7 . FIG. 7 illustrates an embodiment of a direct LED driving circuit. Like many adaptive LED direct drivers, this embodiment needs to modify the LED current to provide a stable and appropriate output voltage to add or remove secondary LED light strings attached to the main LED light string 10. 20 quantity.

In this embodiment, the direct LED driver includes a current sensing resistor 80, a first transistor 81, an internal current source 82, an exceeding diode 83, an error amplifier 84, a MONS Transistor 85 , an offset resistor 86 and a REST resistor 87 .

Wherein, the current sensing resistor 80 is connected to the first end of the main LED light string 10 and the preset element 30 . The first transistor 81 has three terminals, wherein the first terminal is connected to the current sensing resistor 80 , and the second terminal is connected to the second terminal of the secondary LED light string group 20 . The connection of the current sense resistor 80 and the first transistor 81 can sense the complete voltage flowing through the main LED light string 10 and the additional secondary LED light string 200 (a part of the current flowing through the current sense resistor 80 is converted to supply the main LED light string string 10 and an additional secondary LED string 200). The internal current source 82 is connected to the third end of the first transistor, and the current value of the current source 82 is preset to reach the minimum output voltage (that is, the minimum predicted voltage of the direct LED driving device), The current values sensed by the current sensing resistors 80 are the same.

The conduction diode 83 has an anode and a cathode, wherein the anode is connected to the third terminal of the first transistor 81 . The error amplifier 84 has a positive input, a negative input and an output, wherein the positive input of the error amplifier 84 is connected to a reference voltage source (reference voltage source, Vrs), and the negative input of the error amplifier 84 The terminal is connected to the cathode of the conduction diode 83 . The MONS transistor 85 has three terminals, wherein the first terminal is connected to the second terminal of the secondary LED light string group 20 , the second terminal is connected to the output terminal of the error amplifier 84 , and the third terminal is connected to the REST resistor 87 . The offset resistor 86 is connected between the negative input of the error amplifier 84 and the REST resistor 87 . Error amplifier 84 and MONS transistor 85 form a base current source, like current source 401 described in the preceding paragraph.

When the current value flowing through the current sensing resistor 80 is greater than the preset value of the internal current source 82, the excessive current will flow to the divert diode 83, and at this time, a voltage drop across the offset resistor 86 will occur, Further, an offset voltage between the reference voltage source Vrs and the REST resistor 87 is generated, and the current flowing through the LED is reduced. The reduced current value can be expressed by the following equation:

ILED=(Vrs-R86×((VLED/R80)-I82))/R87.

Wherein, Vrs is the voltage value of the reference voltage source, R86 is the resistance value of the offset resistor 86 , R80 is the resistance value of the current sensing resistor 80 , I82 is the current value of the internal current source, and R87 is the resistance value of the REST resistor 87 .

Claims (12)

1. A direct type light-emitting diode driving device, is characterized in that, system comprises: A main LED light string includes a plurality of LED units connected in series, and has a first end and a second end; A secondary LED light string group has a first end and a second end, and includes a plurality of secondary LED light strings connected in series, the first end of the secondary LED light string group is connected to the the second end of the main LED string; A presetting element, including: a diode rectifier connected to a power source for converting an AC input voltage of said power source into a pulsed DC voltage; and A power factor correction module, connected between the diode rectifier and the first end of the main LED light string, adjusts the pulsed DC voltage to a stable output voltage, wherein the stable a voltage output to drive the primary LED string, the secondary LED string group, or both the primary LED string and the secondary LED string group; and A direct driver has a current source connected to each of the secondary LED light strings to selectively turn off selected secondary LED light strings. 2 . The direct-type light-emitting diode driving device as claimed in claim 1 , further comprising a communication path between the preset element and the direct-type driver. 3 . 3. The direct-type light-emitting diode driving device as claimed in claim 1, wherein the direct-type driver further comprises: a current feedback path connected to a controller of the preset element; and A current feedback module is used to generate a control voltage to the controller of the preset device through the current feedback path to regulate the output stable voltage. 4. The direct light-emitting diode driving device as claimed in claim 3, characterized in that: The current feedback module further includes: an integrating circuit connected between said secondary LED string group and said current source; and a current channel is connected to the integrating circuit and uses an indirect diode to selectively regulate the current flowing into the current source; The current feedback path further includes: a first resistor; A second resistor is connected in series with the first resistor of the current feedback path, and a junction of the first resistor and the second resistor is connected to an internal comparator inside the controller, so The internal comparator has an internal reference voltage; and A third resistor has a first terminal and a second terminal, the first terminal is connected to a junction of the first resistor and the second resistor, and the second terminal is connected to the current channel . 5. The direct light-emitting diode driving device as claimed in claim 4, characterized in that: said comparator consists of an operational amplifier with a reference voltage; and The current channel is an inverter, which supplies current when the voltage of the current source is higher than the reference voltage. 6. The direct light-emitting diode driving device as claimed in claim 4, characterized in that: the integrating circuit consists of a transfer conductance driving a comparator; and The current channel is a buffer. 7. The direct-type light-emitting diode driving device as claimed in claim 3, wherein the preset device is coupled to a plurality of direct-type drivers. 8. The direct-type light-emitting diode driving device as claimed in claim 7, wherein each of the direct-type drivers has a current feedback module, which makes the current flow out from the current feedback path, and the outflow current A control voltage is generated. 9. The direct light-emitting diode driving device as claimed in claim 8, wherein the The current feedback path further includes: a first resistor; A second resistor is connected in series with the first resistor, a junction of the first resistor and the second resistor is connected to an internal comparator inside the controller, and the internal comparator has an internal reference voltage; and A third resistor has a first terminal connected to a junction of the first resistor and the second resistor. 10. The direct-type light-emitting diode driving device as claimed in claim 9, wherein the direct-type light-emitting diode driving device further comprises a protection diode, and the protection diode system is arranged on the between the third resistor and the current channel, and allow current to flow from the junction of the first resistor and the second resistor to the preset element. 11. The direct-type light-emitting diode driving device according to claim 1, wherein the direct-type light-emitting diode driving device comprises: a current sensing resistor for sensing a current corresponding to the voltage of the primary LED light string to which the secondary LED light string is attached; an internal current source having a preset current, the preset current is equal to the current value sensed by the current sensing resistor when the preset current is equal to the minimum voltage value of the regulated output voltage; a current-steering diode; a first resistor, when the current value sensed by the current sensing resistor is higher than the current value preset by the internal current source, the first resistor allows excess current to flow into the conduction diode ; an error amplifier having a reference voltage source; a NOMS transistor connected to the error amplifier to form the current source; an offset resistor; and A REST resistor is connected to the conduction diode and generates a bias voltage between the reference voltage source and the REST resistor, wherein the bias voltage reduces the current flowing into the LED light string. 12. The direct light emitting diode driving device according to claim 11, characterized in that: The current sensing resistor is connected to the first end of the main LED light string and the preset element; The first resistor has a first terminal, a second terminal and a third terminal, wherein the first terminal is connected to the current sensing resistor, and the second terminal is connected to the secondary the second end of the LED light string group; The internal current source is connected to the third terminal of the first resistor; The conduction diode has an anode and a cathode, wherein the anode is connected to the third end of the first resistor; The error amplifier has a positive input terminal, a negative input terminal and an output terminal, wherein: The positive input terminal is connected to a reference voltage source; The negative input terminal is connected to the cathode of the steering diode; The NMOS transistor has a first end, a second end and a third end, wherein the first end is connected to the second end of the secondary LED light string group, and the second end is connected to at the first output of the error amplifier, the third terminal is connected to the REST resistor; and The bias resistor is connected between the negative output terminal of the error amplifier and the REST resistor.