CN112770460A

CN112770460A - Drive device

Info

Publication number: CN112770460A
Application number: CN201910992633.8A
Authority: CN
Inventors: 詹子增
Original assignee: Acer Inc
Current assignee: Acer Inc
Priority date: 2019-10-18
Filing date: 2019-10-18
Publication date: 2021-05-07
Anticipated expiration: 2039-10-18
Also published as: CN112770460B

Abstract

A driving apparatus for driving a light emitting module, comprising: the power converter comprises a bridge rectifier, a first capacitor, an inductance control circuit, a transformer, a power switcher, an output stage circuit and a controller. The bridge rectifier generates a rectified potential. The inductance control circuit includes an inductor and adjusts an inductance current passing through the inductor according to a rectified potential and a first control potential, wherein the first control potential is selectively used for performing a pulse frequency modulation operation. The transformer generates a transformation potential according to an inductance potential related to the inductor. The output stage circuit generates an output potential according to the transformed potential. The light emitting component determines whether to generate light according to the output potential. The controller detects the rectified voltage and determines a first control voltage according to the rectified voltage.

Description

Drive device

Technical Field

The present invention relates to a driving device, and more particularly, to a driving device for driving a light emitting device.

Background

In lighting applications of light emitting assemblies, the most common problem is stroboscopic (Flicker), which means that the brightness of light varies periodically with time. Generally, when the switching frequency of the light is below 60Hz, human eyes can easily detect the flickering of the light source, and when the switching frequency of the light is above 60Hz, although the human eyes cannot easily detect the flickering, the human eyes still easily cause eye fatigue and discomfort. In view of the above, a new solution is proposed to overcome the drawbacks of the prior art.

Disclosure of Invention

In a preferred embodiment, the present invention provides a driving apparatus for driving a light emitting device, and the driving apparatus includes: a bridge rectifier for generating a rectified potential according to a first input potential and a second input potential; a first capacitor for storing the rectified potential; an inductance control circuit, including an inductor, and adjusting an inductance current passing through the inductor according to the rectified potential and a first control potential to generate an inductance potential, wherein the first control potential is selectively used for performing a pulse frequency modulation operation; a transformer, including a primary coil, a secondary coil and an auxiliary coil, wherein the primary coil is used for receiving the inductive potential, and the secondary coil is used for generating a transformation potential; a power switch, wherein the main coil is coupled to a ground potential via the power switch, and the power switch performs a switching operation according to a clock potential; an output stage circuit for generating an output potential according to the transformed potential, wherein the light emitting component determines whether to generate a light according to the output potential; and a controller coupled to the bridge rectifier and detecting the rectified voltage, wherein the controller determines the first control voltage and the clock voltage according to the rectified voltage.

Drawings

Fig. 1 is a schematic diagram illustrating a driving device according to an embodiment of the invention.

Fig. 2 is a schematic diagram illustrating a driving device according to an embodiment of the invention.

Fig. 3 is a schematic diagram illustrating a driving device according to an embodiment of the invention.

Fig. 4 is a waveform diagram illustrating a driving apparatus according to an embodiment of the invention.

Fig. 5 is a waveform diagram illustrating a driving apparatus according to an embodiment of the invention.

Fig. 6 is a waveform diagram illustrating an exemplary pulse frequency modulation operation according to an embodiment of the present invention.

Fig. 7 is a waveform diagram illustrating a pwm operation according to an embodiment of the present invention.

List of reference numerals

100. 200, 300 to a driving device;

110. 210-a bridge rectifier;

120. 220, 320-inductance control circuit;

130. 230-a transformer;

131. 231-main coil;

132. 232-secondary coil;

133. 233-auxiliary coil;

140. 240-power switcher;

150. 250-output stage circuit;

160. 260, 360-controller;

190. 290 to a light emitting assembly;

c1-first capacitor;

c2-second capacitor;

CC1 — first curve;

CC 2-second curve;

CC 3-third curve;

CC 4-fourth curve;

d1-a first diode;

d2-second diode;

d3-third diode;

d4 fourth diode;

d5-fifth diode;

d6 sixth diode;

IL-inductor current;

l1 inductor;

m1-first transistor;

m2-second transistor;

m3 third transistor;

n1-first node;

n2-second node;

n3-third node;

n4-fourth node;

n5-fifth node;

n6-sixth node;

NIN 1-first input node;

NIN 2-a second input node;

NOUT-output node;

r1-resistor;

t1-first switching period;

t2-second switching period;

t3-third switching period;

t4-fourth switching period;

TA to the first stage;

TB represents the second stage;

TC to a third stage;

TON 1-first on time;

TON 2-second on time;

TON3 to a third on time;

TON4 to a fourth on time;

VA-clock potential;

VC 1-a first control potential;

VC 2-a second control potential;

VCC-supply potential;

VIN 1-first input potential;

VIN2 to a second input potential;

VL-inductance potential;

VOUT-output potential;

VR-rectified potential;

VS-variable voltage potential;

VSS to ground potential.

Detailed Description

In order to make the objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below.

Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The term "substantially" means within an acceptable error range, within which a person skilled in the art can solve the technical problem to achieve the basic technical result. In addition, the term "coupled" is used herein to encompass any direct or indirect electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.

Fig. 1 is a schematic diagram illustrating a driving apparatus 100 according to an embodiment of the invention. The driving apparatus 100 is used for driving a light emitting module 190. For example, the driving apparatus 100 may be applied to a desktop computer, a notebook computer, or an integrally formed computer. As shown in fig. 1, the driving apparatus 100 includes: bridge rectifier 110, first capacitor C1, inductance control circuit 120, transformer 130, power switch 140, output stage circuit 150, and controller 160. It should be noted that although not shown in fig. 1, the driving device 100 may also include other components, such as: a voltage regulator or (and) a negative feedback circuit.

The bridge rectifier 110 generates the rectified voltage VR according to the first input voltage VIN1 and the second input voltage VIN 2. The first input potential VIN1 and the second input potential VIN2 can be derived from an external power source, wherein an ac voltage with any frequency and any amplitude can be formed between the first input potential VIN1 and the second input potential VIN 2. For example, the frequency of the ac voltage may be about 50Hz or 60Hz, and the root-mean-square value of the ac voltage may be about 110V or 220V, but is not limited thereto. The first capacitor C1 may be used to store the rectified potential VR. Inductance control circuit 120 includes inductor L1. The inductance control circuit 120 adjusts the inductor current IL through the inductor L1 according to the rectified voltage VR and the first control voltage VC1 to generate the inductance voltage VL, wherein the first control voltage VC1 is selectively used for performing a pulse frequency modulation operation. The transformer 130 includes a primary winding 131, a secondary winding 132, and an auxiliary winding 133, wherein the primary winding 131 and the auxiliary winding 133 can be located on the same side of the transformer 130, and the secondary winding 132 can be located on the opposite side of the transformer 130. The primary winding 131 is for receiving an inductive potential VL, and the secondary winding 132 is for generating a transforming potential VS in response to the inductive potential VL. The auxiliary coil 133 is coupled to the controller 160. The main winding 131 is coupled to a ground potential VSS (e.g., 0V) via a power switch 140. The power switch 140 is switched according to a clock potential VA, and is alternately turned on or off. The output stage circuit 150 generates the output voltage VOUT according to the transformation voltage VS, wherein the light emitting device 190 determines whether to generate a light according to the output voltage VOUT. For example, if the output voltage VOUT is at a high logic level, the light emitting device 190 will generate light, and if the output voltage VOUT is at a low logic level, the light emitting device 190 will not generate any light. The controller 160 may be a control integrated circuit, which may be coupled to the bridge rectifier 110. In some embodiments, the controller 160 includes a detection circuit, a comparison circuit, and a processing circuit (not shown). The controller 160 can detect the rectified voltage level VR and compare the detected rectified voltage level VR with a first threshold value, wherein the controller 160 determines the first control voltage level VC1 and the clock voltage level VA according to the rectified voltage level VR. For example, if the rectified voltage VR is lower than the first threshold, the first control voltage VC1 performs the pulse frequency modulation operation; otherwise, if the rectified voltage VR is higher than or equal to the first threshold, no pulse frequency modulation operation is performed. The clock level VA can be maintained at a fixed level when the driving device 100 is initialized, and can provide a periodic clock waveform after the driving device 100 enters a normal use stage. According to the actual measurement result, the circuit design can reduce the undesirable stroboscopic phenomenon, so that the light-emitting device 190 using the driving apparatus 100 will not easily cause eye fatigue of the user.

The following embodiment will describe the detailed structure and operation of the driving device 100. It must be understood that these drawings and descriptions are only exemplary and are not intended to limit the scope of the present invention.

Fig. 2 is a schematic diagram illustrating a driving device 200 according to an embodiment of the invention. In the embodiment of fig. 2, the driving apparatus 200 has a first input node NIN1, a second input node NIN2, and an output node NOUT, and includes a bridge rectifier 210, a first capacitor C1, an inductance control circuit 220, a transformer 230, a power switch 240, an output stage circuit 250, and a controller 260. The first input node NIN1 and the second input node NIN2 of the driving apparatus 200 can receive a first input voltage VIN1 and a second input voltage VIN2 from an external power source, respectively, and the output node NOUT of the driving apparatus 200 can be used for outputting an output voltage VOUT to a light emitting device 290. For example, the light emitting element 290 may include one or more light emitting diodes connected in series between the output node NOUT and a ground potential VSS. The total number of light emitting diodes is not particularly limited in the present invention. If the output voltage VOUT is at a high logic level, the light emitting element 290 will generate a light, and if the output voltage VOUT is at a low logic level, the light emitting element 290 will not generate any light. In other embodiments, the light emitting diode may be a sub-millimeter light emitting diode, a micro light emitting diode, or an organic light emitting diode, but is not limited thereto.

The bridge rectifier 210 includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The anode of the first diode D1 is coupled to the first input node NIN1, and the cathode of the first diode D1 is coupled to a first node N1 for outputting a rectified voltage VR. The anode of the second diode D2 is coupled to the first input node NIN1, and the cathode of the second diode D2 is coupled to the ground potential VSS. An anode of the third diode D3 is coupled to the first node N1, and a cathode of the third diode D3 is coupled to the second input node NIN 2. The anode of the fourth diode D4 is coupled to the ground potential VSS, and the cathode of the fourth diode D4 is coupled to the second input node NIN 2.

The first terminal of the first capacitor C1 is coupled to the first node N1 for receiving the rectified potential VR, and the second terminal of the first capacitor C1 is coupled to the ground potential VSS.

The inductance control circuit 220 includes a fifth diode D5, a first transistor M1, and an inductor L1. The anode of the fifth diode D5 is coupled to the first node N1 for receiving the rectified voltage VR, and the cathode of the fifth diode D5 is coupled to a second node N2 for outputting an inductor voltage VL. The first transistor M1 may be an nmos field effect transistor. The control terminal of the first transistor M1 is for receiving a first control potential VC1, the first terminal of the first transistor M1 is coupled to a third node N3, and the second terminal of the first transistor M1 is coupled to the first node N1. A first terminal of the inductor L1 is coupled to the third node N3, and a second terminal of the inductor L1 is coupled to the second node N2. Generally, the inductance control circuit 220 adjusts an inductance current IL passing through the inductor L1 according to the rectified potential VR and the first control potential VC1, so as to determine the inductance potential VL at the second node N2.

The transformer 230 includes a primary winding 231, a secondary winding 232, and an auxiliary winding 233. The first terminal of the primary winding 231 is coupled to the second node N2 for receiving the inductor potential VL, and the second terminal of the primary winding 231 is coupled to a fourth node N4. The first terminal of the secondary winding 232 is coupled to a fifth node N5 for outputting a transforming potential VS, and the second terminal of the secondary winding 232 is coupled to the ground potential VSS. The first terminal of the auxiliary winding 233 is coupled to the controller 260 for receiving a supply potential VCC, and the second terminal of the auxiliary winding 233 is coupled to the ground potential VSS. For example, the supply potential VCC may be a fixed potential.

The power switch 240 includes a second transistor M2. The second transistor M2 may be an nmos field effect transistor. The control terminal of the second transistor M2 is for receiving a clock potential VA, the first terminal of the second transistor M2 is coupled to the ground potential VSS, and the second terminal of the second transistor M2 is coupled to the fourth node N4.

The output stage circuit 250 includes a sixth diode D6, a second capacitor C2, and a resistor R1. The anode of the sixth diode D6 is coupled to the fifth node N5 for receiving the transforming potential VS, and the cathode of the sixth diode D6 is coupled to a sixth node N6. The first terminal of the second capacitor C2 is coupled to the sixth node N6, and the second terminal of the second capacitor C2 is coupled to the ground potential VSS. A first terminal of the resistor R1 is coupled to the sixth node N6, and a second terminal of the resistor R1 is coupled to the output node NOUT.

The controller 260 is coupled to the first node N1 of the bridge rectifier 210 and is configured to detect the rectified voltage VR, wherein the controller 260 determines the first control voltage VC1 and the clock voltage VA according to the rectified voltage VR. The first control potential VC1 is selectively used for performing a pulse frequency modulation operation. For example, if the rectified voltage VR is lower than a first threshold, the first control voltage VC1 performs the pwm operation; on the contrary, if the rectified voltage VR is higher than or equal to the first threshold, no pwm operation is performed, and the first control voltage VC1 can be maintained at a low logic level.

Fig. 3 is a schematic diagram illustrating a driving device 300 according to an embodiment of the invention. Fig. 3 is similar to fig. 2. In the embodiment of fig. 3, an inductance control circuit 320 of the driving apparatus 300 further adjusts the inductor current IL passing through the inductor L1 according to a second control potential VC2, and a controller 360 of the driving apparatus 300 further determines the second control potential VC2 according to the rectified potential VR, wherein the second control potential VC2 is selectively used for performing a pulse width modulation operation. For example, if the rectified voltage VR is higher than a second threshold, the second control voltage VC2 performs pwm operation; on the contrary, if the rectified voltage VR is lower than or equal to the second threshold, no pwm operation is performed, and the second control voltage VC2 can be maintained at the low logic level. It should be noted that the second threshold value may be higher than the first threshold value. In detail, the inductance control circuit 320 further includes a third transistor M3. The third transistor M3 may be an nmos field effect transistor. The control terminal of the third transistor M3 is for receiving the second control potential VC2, the first terminal of the third transistor M3 is coupled to the third node N3, and the second terminal of the third transistor M3 is coupled to the first node N1. According to the actual measurement result, the third transistor M3 is added to further suppress the undesired stroboscopic phenomenon of the light emitting element 290. The remaining features of the driving device 300 of fig. 3 are similar to those of the driving device 200 of fig. 2, so that the two embodiments can achieve similar operation effects.

The following embodiments will describe how the pulse frequency modulation operation and the pulse width modulation operation of the driving device 300 can reduce the stroboscopic effect of the light emitting element 290. It should be noted that the operation principle of the driving device 100 of fig. 1 and the driving device 200 of fig. 2 can also be explained.

Fig. 4 is a waveform diagram of a driving apparatus 300 according to an embodiment of the invention, in which the horizontal axis represents time and the vertical axis represents a potential level or a current value. Taking a 60Hz ac voltage as an example, the frequency of the ac voltage will be 120Hz after passing through the bridge rectifier 210, which is a main reason for the stroboscopic phenomenon of the light emitting element 290. As shown in fig. 4, a first curve CC1 represents the waveform of the rectified potential VR (corresponding to the potential level on the vertical axis), and a second curve CC2 represents the waveform of the inductor current IL (corresponding to the current level on the vertical axis). That is, the inductor L1 acts as an energy storage device, and the inductor current IL passing through the inductor L1 is alternately increased and decreased in response to the change of the rectified voltage VR. With this design, after the rectified voltage VR is processed by the inductance control circuit 320, the equivalent frequency of the generated inductance voltage VL is significantly increased, which can prevent the light emitting device 290 from generating undesired stroboflash.

Fig. 5 is a waveform diagram of the driving apparatus 300 according to an embodiment of the invention, in which the horizontal axis represents time, and the vertical axis represents a potential level or a current value. Fig. 5 can be regarded as a partial enlarged view of fig. 4. As shown in fig. 5, a third curve CC3 represents the waveform of the rectified potential VR (corresponding to the potential level on the vertical axis), and a fourth curve CC4 represents the waveform of the inductor current IL (corresponding to the current level on the vertical axis). In detail, in response to the gradually increasing rectified voltage VR, the inductor L1 can be sequentially operated in a first phase TA, a second phase TB, and a third phase TC. During the first phase TA, the inductor L1 operates in a discontinuous conduction mode, the energy storing speed is slow, and the energy releasing speed is fast, so the inductor current IL drops to 0 early at the end of the first phase TA. During the second phase TB, the inductor L1 is operated in a boundary conduction mode, and its energy storage speed is approximately equal to its energy release speed, so the inductor current IL drops to 0 exactly at the end of the second phase TB. During the third phase TC, the inductor L1 operates in a continuous conduction mode, and the energy storage speed is faster and the energy release speed is slower, so the inductor current IL has not decreased to 0 at the end of the third phase TC. On the contrary, in response to the gradually decreasing rectified voltage VR, the inductor L1 can be sequentially operated in the third phase TC, the second phase TB, and the first phase TA, and the principle thereof is similar and will not be repeated. According to the actual measurement results, when the inductor L1 operates in the boundary conduction mode, the loss of the driving device 300 is the lowest and the conversion efficiency is the highest. It should be noted that the pulse frequency modulation operation or (and) the pulse width modulation operation described above facilitates the inductor L1 to enter the boundary conduction mode, as described below.

Fig. 6 is a waveform diagram illustrating a pulse frequency modulation operation according to an embodiment of the invention, wherein the horizontal axis represents time and the vertical axis represents potential level. When performing the pulse frequency modulation operation, the switching frequency of the first control potential VC1 is variable, but the on-time of the first control potential VC1 is fixed in each switching period. As shown in fig. 6, a first switching period T1 and a second switching period T2 of the first control potential VC1 have different lengths (i.e., different switching frequencies), but a first on-time TON1 of the first switching period T1 and a second on-time TON2 of the second switching period T2 have the same length. Based on actual measurements, the pulse frequency modulation operation can be used to modify inductor L1 in discontinuous conduction mode, which forces inductor L1 to enter boundary conduction mode earlier.

Fig. 7 is a waveform diagram illustrating a pwm operation according to an embodiment of the present invention, wherein the horizontal axis represents time and the vertical axis represents potential level. When performing the pwm operation, the switching frequency of the second control potential VC2 is fixed, but the on-time of the second control potential VC2 is variable in each switching period. As shown in fig. 7, a third switching period T3 and a fourth switching period T4 of the second control potential VC2 have the same length (i.e., the same switching frequency), but a third on-time TON3 of the third switching period T3 and a fourth on-time TON4 of the fourth switching period T4 have different lengths. Based on actual measurements, the pwm operation can be used to modify inductor L1 in continuous conduction mode, which forces inductor L1 into boundary conduction mode earlier.

In summary, the inductance control circuit 320 operates as described in table one below:

table one: operation mode of inductance control circuit 320

In some embodiments, the controller 360 determines the first control potential VC1 or (and) the second control potential VC2 according to the detected rectified potential VR. For example, if the rectified voltage VR is lower than the first threshold, the first transistor M1 will perform the pulse frequency modulation operation according to the first control voltage VC 1; if the rectified voltage VR is higher than the second threshold, the third transistor M3 performs pwm operation according to the second control voltage VC 2; if the rectified voltage VR is between the first threshold and the second threshold, neither the pulse frequency modulation operation nor the pulse width modulation operation is performed.

In some embodiments, the inductance control circuit 320 includes the first transistor M1 but not the third transistor M3, i.e., only the pulse frequency modulation operation is selectively used. In other embodiments, the inductance control circuit 320 includes the third transistor M3 but not the first transistor M1, i.e., only the pwm operation is selectively used. Both of the above embodiments can exert similar technical effects to those of the foregoing embodiments.

In some embodiments, the component parameters of any of the

drive devices

100, 200, 300 may be as follows. The resistor R1 may have a resistance value of 423 Ω to 517 Ω, preferably 470 Ω. The capacitance of the first capacitor C1 may be between 96 μ F and 144 μ F, preferably 120 μ F. The second capacitor C2 may have a capacitance value of 544 μ F to 816 μ F, preferably 680 μ F. The inductance of inductor L1 may be between 80 μ H and 120 μ H, preferably 100 μ H. The ratio of the number of turns of the primary coil 231 to the secondary coil 232 may be between 1 and 40, preferably 20. The ratio of the number of turns of the secondary winding 232 to the auxiliary winding 233 may be between 1 and 3, preferably 1.33. The first control potential VC1 for performing the pulse frequency modulation operation has a frequency conversion range between 40kHz and 60 kHz. The second control potential VC2 for performing the pulse width modulation operation has a fixed frequency between 60 kHz. The first threshold value may be equal to about 30% of the maximum value of the rectified potential VR. The second threshold value may be equal to about 60% of the maximum value of the rectified potential VR. The above parameter ranges are derived from a plurality of experimental results, which are helpful for optimizing the conversion efficiency of the driving

apparatuses

100, 200, 300 and effectively suppressing the stroboscopic phenomenon.

The present invention provides a novel driving device, which includes an inductance control circuit. According to the actual measurement result, the driving device using the inductance control circuit can inhibit the non-ideal stroboflash of the corresponding light-emitting component so as to reduce the eye fatigue and discomfort of a user. In general, the driving device of the present invention is not easily affected by the low frequency noise of the general utility power, so it is suitable for various electronic devices.

It should be noted that the above-mentioned potential, current, resistance, inductance, capacitance, and other device parameters are not limitations of the present invention. The designer can adjust these settings according to different needs. The driving apparatus of the present invention is not limited to the states illustrated in fig. 1 to 7. The present invention may include only any one or more of the features of any one or more of the embodiments of figures 1-7. In other words, not all of the features shown in the drawings need to be implemented in the driving device of the present invention at the same time. Although the embodiments of the present invention use mosfet as an example, the present invention is not limited thereto, and other kinds of transistors can be used by those skilled in the art, such as: junction field effect transistors, fin field effect transistors, etc., without affecting the effect of the present invention.

Ordinal numbers such as "first," "second," "third," etc., in the specification and in the claims are not used sequentially to distinguish one element from another, but merely to identify two different elements having the same name.

Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A driving apparatus for driving a light emitting module, comprising:

a bridge rectifier for generating a rectified potential according to a first input potential and a second input potential;

a first capacitor for storing the rectified potential;

an inductance control circuit, including an inductor, and adjusting an inductance current passing through the inductor according to the rectified potential and a first control potential to generate an inductance potential, wherein the first control potential is selectively used for performing a pulse frequency modulation operation;

a transformer, including a primary coil, a secondary coil and an auxiliary coil, wherein the primary coil is used for receiving the inductive potential, and the secondary coil is used for generating a transformation potential;

a power switch, wherein the main coil is coupled to a ground potential via the power switch, and the power switch performs a switching operation according to a clock potential;

an output stage circuit for generating an output potential according to the transformed potential, wherein the light emitting component determines whether to generate a light according to the output potential; and

a controller coupled to the bridge rectifier and detecting the rectified voltage, wherein the controller determines the first control voltage and the clock voltage according to the rectified voltage.

2. The driving apparatus of claim 1, wherein the bridge rectifier comprises:

a first diode having an anode and a cathode, wherein the anode of the first diode is coupled to a first input node for receiving the first input potential, and the cathode of the first diode is coupled to a first node for outputting the rectified potential;

a second diode having an anode and a cathode, wherein the anode of the second diode is coupled to the first input node and the cathode of the second diode is coupled to the ground potential;

a third diode having an anode and a cathode, wherein the anode of the third diode is coupled to the first node and the cathode of the third diode is coupled to a second input node for receiving the second input potential; and

a fourth diode having an anode and a cathode, wherein the anode of the fourth diode is coupled to the ground potential and the cathode of the fourth diode is coupled to the second input node.

3. The driving apparatus of claim 2, wherein the inductance control circuit further comprises:

a fifth diode having an anode and a cathode, wherein the anode of the fifth diode is coupled to the first node for receiving the rectified potential, and the cathode of the fifth diode is coupled to a second node for outputting the inductor potential; and

a first transistor having a control terminal, a first terminal, and a second terminal, wherein the control terminal of the first transistor is configured to receive the first control potential, the first terminal of the first transistor is coupled to a third node, and the second terminal of the first transistor is coupled to the first node;

the inductor has a first end and a second end, the first end of the inductor is coupled to the third node, and the second end of the inductor is coupled to the second node.

4. The driving apparatus as claimed in claim 3, wherein the main coil has a first end and a second end, the first end of the main coil is coupled to the second node for receiving the inductor potential, the second end of the main coil is coupled to a fourth node, the auxiliary coil has a first end and a second end, the first end of the auxiliary coil is coupled to a fifth node for outputting the transforming potential, the second end of the auxiliary coil is coupled to the ground potential, the auxiliary coil has a first end and a second end, the first end of the auxiliary coil is received by the controller, and the second end of the auxiliary coil is coupled to the ground potential.

5. The driving apparatus of claim 4, wherein the power switch comprises:

a second transistor having a control terminal, a first terminal, and a second terminal, wherein the control terminal of the second transistor is used for receiving the clock potential, the first terminal of the second transistor is coupled to the ground potential, and the second terminal of the second transistor is coupled to the fourth node.

6. The driving apparatus of claim 4, wherein the output stage circuit comprises:

a sixth diode having an anode and a cathode, wherein the anode of the sixth diode is coupled to the fifth node for receiving the transforming potential, and the cathode of the sixth diode is coupled to a sixth node;

a second capacitor having a first terminal and a second terminal, wherein the first terminal of the second capacitor is coupled to the sixth node and the second terminal of the second capacitor is coupled to the ground potential; and

a resistor having a first end and a second end, wherein the first end of the resistor is coupled to the sixth node, and the second end of the resistor is coupled to an output node to output the output potential.

7. The driving apparatus of claim 6, wherein the light emitting device comprises one or more light emitting diodes connected in series between the output node and the ground potential.

8. The driving apparatus as claimed in claim 3, wherein the inductance control circuit further adjusts the inductance current passing through the inductor according to a second control potential, the controller further determines the second control potential according to the rectified potential, and the second control potential is selectively used for performing a pulse width modulation operation.

9. The driving apparatus of claim 8, wherein the inductance control circuit further comprises:

a third transistor having a control terminal, a first terminal, and a second terminal, wherein the control terminal of the third transistor is configured to receive the second control potential, the first terminal of the third transistor is coupled to the third node, and the second terminal of the third transistor is coupled to the first node.

10. The driving device as claimed in claim 8, wherein the pulse frequency modulation operation is performed if the rectified potential is lower than a first threshold, the pulse width modulation operation is performed if the rectified potential is higher than a second threshold, and neither the pulse frequency modulation operation nor the pulse width modulation operation is performed if the rectified potential is between the first threshold and the second threshold.