TW201304597A - Light emitting diode driving circuit - Google Patents

Abstract

A light-emitting diode driving circuit includes an input power circuit, a light-emitting diode string, a boost converter, a feedback resistor and a control circuit. The light-emitting diode string includes a partial pressure point, and the boost converter includes a switching transistor. The input power circuit is used to output a current signal, the boost converter uses the current signal to output a driving signal. The feedback resistor uses the driving signal or a first signal output by the switching transistor to output a feedback signal. The light-emitting diode string uses the partial pressure point to provide a starting voltage to the control circuit to make the control circuit output a pulse width modulation signal according to the feedback signal, so as to selectively start or shut the switching transistor. The starting voltage is greater than or equal to a working voltage of the control circuit. Therefore, the light-emitting diode driving circuit can start control circuit without an external starting circuit.

Description

Light-emitting diode driving circuit

The present invention provides a light emitting diode driving circuit, and more particularly to a non-isolated light emitting diode driving circuit.

In terms of lighting devices, since the light-emitting diodes have advantages of long life, low power consumption, and low damage, the light-emitting diodes have become human beings in research and development and life applications. Important object. However, the light emitting diode needs to be driven by a DC power source. Therefore, when the light emitting diode is applied to receive AC power, the LED driving circuit is required to convert the AC power into a DC power source to drive the LED to emit light.

At present, the AC-DC converter on the market adopts a non-isolated or isolated architecture, usually by driving a switching transistor through a control circuit to perform high-frequency modulation of the input AC power source. Then, the filter circuit composed of the inductor and the capacitor is rectified and filtered to output the DC power to the load terminal. When the AC power supply is just input to the AC-DC converter, the AC-DC converter is not yet in operation, and it is usually necessary to provide a starting voltage to the control circuit by the starting circuit, so that the control circuit activates the switching transistor, thereby starting the AC-DC converter. Operation. When the AC-DC converter starts operating, additional power is supplied to the control circuit through the output of the AC-DC converter.

The conventional starting circuit is composed of a power resistor. Therefore, after the control circuit is started by the starting circuit, the starting circuit cannot be actively stopped, and the power is continuously consumed, thereby failing to meet the low standby power requirement. In order to meet the requirements of low standby power, the manufacturer proposes a starting circuit with a high voltage current source. When the control circuit is not activated, the active switch is used to generate a high voltage constant current source to start the control circuit and charge the storage capacitor; when the control circuit is started, the high voltage constant current source is turned off to reduce power loss. Although the existing technology has enabled the AC-DC converter to achieve low standby power requirements, the startup circuit with a high-voltage current source requires a large number of components, in addition to increasing the manufacturing cost of the AC-DC converter, and also enables AC- The volume of the DC converter is increased.

In view of the above problems, the present proposal proposes a light-emitting diode driving circuit to solve the problems of the prior art.

According to an embodiment of the LED driving circuit disclosed in the present proposal, the LED driving circuit includes an input power circuit, a LED array, a boost converter, a feedback resistor and a control. Circuit. The LED array includes N light-emitting diodes and a voltage dividing end point, N light-emitting diode systems are coupled in series, and the voltage dividing end is disposed in the k-th light-emitting diode and the k+th Between one light-emitting diode, where N ≧ 2, k +1 ≦ N. The boost converter includes a switching transistor. The input power circuit is configured to output a current signal, and the boost converter outputs a driving signal according to the current signal to drive the LED array. The feedback resistor outputs a feedback signal according to a driving signal or a first signal outputted by the switching transistor, wherein the feedback signal is a voltage signal. The voltage dividing end is coupled to the control circuit, and the LED array provides a starting voltage to the control circuit by the voltage dividing end point, so that the control circuit outputs a Pulse Width Modulation (PWM) signal according to the feedback signal. To selectively activate or deactivate the switching transistor. Wherein, the starting voltage is greater than or equal to an operating voltage of the control circuit.

According to an embodiment of the LED driving circuit disclosed in the present proposal, the LED driving circuit includes an input power circuit, a LED array, a boost converter, a feedback resistor and a control. Circuit. The LED array includes N light-emitting diodes and a voltage dividing end point, N light-emitting diode systems are coupled in series, and the voltage dividing end is disposed in the k-th light-emitting diode and the k+th Between one light-emitting diode, where N ≧ 2, k +1 ≦ N. The boost converter includes a power input end, a power output end, a switch transistor and an output capacitor, the power input end is coupled to the input power circuit, and the power output end is coupled to the LED array and the output capacitor. The feedback resistor is selectively coupled to the LED array, disposed between the N LEDs, or coupled to the switching transistor. The voltage dividing end is coupled to the control circuit, and the control circuit is coupled to the switching transistor.

The boost converter charges the output capacitor according to a current signal outputted by the input power circuit. When the voltage of the output capacitor is greater than the voltage required to turn on the LED array, a driving signal is output to drive the LED array. . The LED array provides a starting voltage to the control circuit through the voltage dividing end, so that the control circuit outputs a Pulse Width Modulation (PWM) signal according to the feedback signal to selectively activate or deactivate the switch. Transistor. Wherein, the starting voltage is greater than or equal to an operating voltage of the control circuit. The feedback resistor selectively outputs a feedback signal according to a driving signal or a first signal outputted by the switching transistor, wherein the feedback signal is a voltage signal.

According to the LED driving circuit disclosed in the proposal, the LED array is driven to drive the LED. The voltage-dividing end point design of the LED array can be used to enable the LED driving circuit to start the control circuit without the conventional starting circuit. Furthermore, the position of the voltage dividing end point can be adjusted according to the operating voltage range required by the different control circuits such that the starting voltage is greater than or equal to the operating voltage of the control power.

The above description of the contents of this proposal and the following description of the implementation are used to demonstrate and explain the spirit and principle of this proposal, and provide a further explanation of the scope of patent application of this proposal.

Please refer to FIG. 1 , which is a schematic diagram of the circuit structure of the first embodiment of the LED driving circuit disclosed in the present proposal. In this embodiment, the LED driving circuit 100 is a non-isolated LED driving circuit, and includes an input power circuit 102, a LED array 104, a boost converter 106, and a feedback resistor 108. And the control circuit 110, the boost converter 106 includes a power input 107, a power output 109, a switching transistor 60, and an output capacitor 98. The power input terminal 107 is coupled to the input power circuit 102. The power output terminal 109 is coupled to one end of the LED array 104 and the output capacitor 98, and the other end of the output capacitor 98 is grounded. One end of the feedback resistor 108 is coupled to the LED array 104, and the other end of the feedback resistor 108 is grounded.

In this embodiment, the LED array 104 can include, but is not limited to, sixty LEDs 20 and a voltage dividing terminal P, and sixty LEDs 20 are coupled in series. The voltage terminal P can be configured, but not limited to, between the fifty-fourth light-emitting diode 20 and the fifty-fifth light-emitting diode 20, but this embodiment is not intended to limit the present proposal. In other words, the LED array 104 can also include twenty LEDs 20, and the voltage dividing terminal P can be configured, but not limited to the fourth LED 20 and the fifth LED 20 Between, it can be adjusted according to actual needs. Here, in order to simplify the drawing of "FIG. 1", only the five representations of the number of the light-emitting diodes 20 included in the LED array 104 are shown.

The input power circuit 102 can include, but is not limited to, an AC signal source 90 and a bridge rectifier 92. The AC signal source 90 is coupled to the bridge rectifier 92, so that the bridge rectifier 92 can receive the AC signal V _ac outputted by the AC signal source 90 and perform a rectification process to output a current signal I _C , wherein the AC signal V _ac is a voltage. signal. The boost converter 106 can further include a first inductor 94 and a first diode 96. One end of the first inductor 94 is coupled to the input power supply circuit 102. The other end of the first inductor 94 is coupled to the input end 961 of the first diode 96. One end of the output capacitor 98 is coupled to the LED array 104. The output 962 of a diode 96.

The LED driving circuit 100 may further include a second diode 62. The switching transistor 60 may be, but not limited to, a Field Effect Transistor (FET). In the present embodiment, the switching transistor 60 can be an N-channel Metal-Oxide-Semiconductor Field Effect Transistor (N-MOSFET), but this embodiment is not intended to limit the proposal. For example, the switching transistor 60 can also be a P-channel gold oxide half field effect transistor. The input end 621 of the second diode 62 is coupled to the source S of the field effect transistor, the output end 622 of the second diode 62 is coupled to the drain D of the field effect transistor, and the control circuit 110 is coupled to the field. The gate G of the effect transistor, but this embodiment is not intended to limit the proposal. For example, the switching transistor 60 can also be a Bipolar Junction Transistor (BJT). The input end 621 of the second diode 62 is coupled to the collector C of the bipolar junction transistor. The output end 622 of the diode 62 is coupled to the emitter E of the bipolar junction transistor, and the control circuit 110 is coupled to the base B of the bipolar junction transistor (as shown in FIG. 2, "Fig. 2 The schematic diagram of the circuit structure of the second embodiment of the LED driving circuit disclosed in the present proposal). Wherein, when the switching transistor 60 is in the off state, the second diode 62 can be used to prevent the counter electromotive force generated by the first inductor 94 from damaging the switching transistor 60, thereby protecting the switching transistor 60.

Please refer to "FIG. 3", which is a schematic diagram of the circuit structure of an embodiment of the control circuit of "FIG. 1". The control circuit 110 can include a triangular wave generator 202, a reference voltage _Vref , a first comparator 204, a second comparator 206, a voltage sensor 208, a pulse width modulation generator 210, and a driver 212. The first comparator 204 includes a first positive input terminal 2041, a first negative input terminal 2042 and a first output terminal 2043. The first positive input terminal 2041 is coupled to the reference voltage V _ref , and the first negative input terminal 2042 receives the feedback signal I . _FB . The second comparator 206 includes a second positive input 2061, a second negative input 2062 and a second output 2063. The second positive input 2061 is coupled to the first output 2043, and the second negative input 2062 is coupled to the triangular wave. 202. The second output end 2063 and one end of the voltage sensor 208 are respectively coupled to the pulse width modulation generator 210, and the other end of the voltage sensor 208 is coupled to the voltage dividing end point P (refer to "1"), pulse The width modulation generator 210 is coupled to the driver 212, and the driver 212 is coupled to the gate G of the field effect transistor (refer to FIG. 1).

Referring to "1" and "3", when the input power supply circuit 102 just outputs the current signal I _C , the control circuit 110 is not activated and the boost converter 106 does not start operating, and the current signal I _C is output. Capacitor 98 is charged. When the voltage of the output capacitor 98 is greater than the voltage of the LED array 104, the drive signal I _D is output to drive the LED array 104. The feedback resistor 108 outputs the feedback signal I _FB to the control circuit 110 according to the driving signal I _D . The feedback signal I _FB is a voltage signal. The LED array 104 provides a startup voltage V _S to the control circuit 110 by the voltage dividing terminal P. When the startup voltage V _{S is} greater than or equal to the operating voltage V _{DD of the} control circuit 110, the first comparator 204 compares the feedback signals. The number I _FB and the reference voltage V _ref output a first comparison signal I _COMP1 to the second comparator 206, and the second comparator 206 compares the size of the first comparison signal I _COMP1 with the triangular wave signal I _TRI output by the triangular wave generator 202 The second comparison signal I _{COMP2 is} output to the pulse width modulation generator 210. The voltage sensor 208 outputs the sensing signal I _se to the pulse width modulation generator 210 by determining that the startup voltage V _{S is} greater than or equal to the operating voltage V _DD . The pulse width modulation generator 210 outputs an actuation signal I _EN to the driver 212 according to the sensing signal I _se and the second comparison signal I _COMP2 , and the driver 212 outputs a pulse width modulation signal I _PWM according to the actuation signal I _EN to selectively The switch transistor 60 is activated or deactivated to adjust the magnitude of the drive signal I _{D that} drives the LED array 104.

For example, the forward voltage of a single LED 20 can be, but is not limited to, 3 volts (Vage), when a single LED 20 receives a forward voltage of about 0.7 to 0.9 times (about 2.1~). At 2.7 volts, a single light-emitting diode 20 begins to conduct. The following is an example in which a single light-emitting diode 20 receives a forward voltage (about 2.4 volts) of about 0.8 times, that is, the conduction is started. In this embodiment, since the number of the light emitting diodes 20 is sixty, the light emitting diode series 104 needs to receive 144 volts to be turned on. Therefore, when the voltage of the output capacitor 98 is greater than 144 volts, the LED array 104 can be driven, thereby causing the LED array 104 to provide a startup voltage V _S greater than or equal to the operating voltage V _DD to the control circuit. 110. It should be noted that since different control circuits have different operating voltages, the voltage dividing end point P can be adjusted according to the operating voltage V _{DD of the} control circuit 110. The starting voltage of the LED _array 104 by the voltage dividing terminal P is the driving voltage of the driving diode series 104 (ie, V _{o_normal} ×(N _low /N _total ), where V _{o_normal} The voltage is greater than or equal to the voltage of the output capacitor that turns on the voltage of the LED array 104, and N _low is the number of the light-emitting diodes 20 from the voltage-dividing end point P to the ground terminal of the LED series 104. N _total is the number of the light-emitting diodes 20 in the light-emitting diode series 104).

In the present embodiment, the control circuit 110 can be, but is not limited to, a control circuit of the type L6561, and the control circuit of the model L6561 requires an operating voltage of between 12 volts and 20 volts. When the voltage of the output capacitor 98 is equal to 144 volts, the threshold voltage V _S provided by the LED array 104 is 144 x (6/60) volts (i.e., 14.4 volts). At this time, the startup voltage V _{S is} greater than the operating voltage required by the control circuit of the model L6561, so the control circuit 110 is activated and the boost converter 106 starts operating.

Please refer to FIG. 4, which is a schematic diagram of the circuit structure of the third embodiment of the LED driving circuit disclosed in the present proposal. The LED driving circuit 100 is a non-isolated LED driving circuit, and includes an input power circuit 102, a LED array 104, a boost converter 106, a feedback resistor 108, and a control circuit 110. The voltage converter 106 includes a power input 107, a power output 109, a switching transistor 60, and an output capacitor 98. The power input terminal 107 is coupled to the input power circuit 102. The power output terminal 109 is coupled to one end of the LED array 104 and the output capacitor 98, and the other end of the output capacitor 98 is grounded. The voltage dividing terminal P is coupled to the control circuit 110, and the control circuit 110 is coupled to the switching transistor 60.

In this embodiment, the LED driving circuit 100 further includes a second inductor 302 and a detecting resistor 304 in addition to the configuration position of the feedback resistor 108 and the structure of the control circuit 110. One end of the feedback resistor 108 is coupled to the boost converter 106, the other end of the feedback resistor 108 is coupled to one end of the LED array 104, and the other end of the LED array 104 is grounded. One end of the second inductor 302 is grounded, the other end of the second inductor 302 is coupled to one end of the detecting resistor 304, and the other end of the detecting resistor 304 is coupled to the control circuit 110.

Please refer to "figure 5", which is a schematic diagram of the circuit structure of an embodiment of the control circuit of "Fig. 4". The control circuit 110 can include a triangular wave generator 202, a reference voltage _Vref , a first comparator 204, a second comparator 206, a voltage sensor 208, a pulse width modulation generator 210, and a driver 212. The first comparator 204 includes a first positive input terminal 2041, a first negative input terminal 2042 and a first output terminal 2043. The first positive input terminal 2041 is coupled to the reference voltage V _ref , and the first negative input terminal 2042 receives the feedback signal I . _FB . The second comparator 206 includes a second positive input 2061, a second negative input 2062 and a second output 2063. The second positive input 2061 is coupled to the first output 2043, and the second negative input 2062 is coupled to the triangular wave. 202. The second output end 2063 and one end of the voltage sensor 208 are respectively coupled to the pulse width modulation generator 210, and the other end of the voltage sensor 208 is coupled to the voltage dividing end point P (refer to "1"), pulse The width modulation generator 210 is coupled to the driver 212, and the driver 212 is coupled to the gate G of the field effect transistor (refer to FIG. 1).

In the present embodiment, the control circuit 110 includes a zero current detector 211 in addition to the architecture of "FIG. 3". One end of the zero current detector 211 is coupled to the detecting resistor 304 (refer to FIG. 4), and the other end of the zero current detector 211 is coupled to the pulse width modulation generator 210.

Referring to "Fig. 4" and "Fig. 5", when the input power supply circuit 102 has just output the current signal I _C , the control circuit 110 is not activated and the boost converter 106 is not operating, and the current signal I _C is output. Capacitor 98 is charged. When the voltage of the output capacitor 98 is greater than the voltage of the LED array 104, the drive signal I _D is output to drive the LED array 104. The feedback resistor 108 outputs the feedback signal I _FB to the control circuit 110 according to the driving signal I _D . The feedback signal I _FB is a voltage signal. The second inductor 302 is configured to detect the current signal I _C flowing through the first inductor 94 and output the detection signal I _Q to the zero current detector 211 of the control circuit 110.

The LED array 104 provides a startup voltage V _S to the control circuit 110 by the voltage dividing terminal P. When the startup voltage V _{S is} greater than or equal to the operating voltage V _{DD of the} control circuit 110, the first comparator 204 compares the feedback signals. The number I _FB and the reference voltage V _ref output a first comparison signal I _COMP1 to the second comparator 206, and the second comparator 206 compares the size of the first comparison signal I _COMP1 with the triangular wave signal I _TRI output by the triangular wave generator 202 The second comparison signal I _{COMP2 is} output to the pulse width modulation generator 210. The voltage sensor 208 outputs the sensing signal I _se to the pulse width modulation generator 210 by determining that the startup voltage V _{S is} greater than or equal to the operating voltage V _DD . The pulse width modulation generator 210 outputs the actuation signal I _EN to the driver 212 according to the sensing signal I _se , the truncation signal I _stop and the second comparison signal I _COMP2 , and the driver 212 outputs the pulse width modulation signal I according to the actuation signal I _{EN The PWM is configured} to selectively activate or deactivate the switching transistor 60 to adjust the magnitude of the driving signal I _{D that} drives the LED array 104. It should be noted that when the detection signal I _Q is zero, the zero current detector 211 outputs the cutoff signal I _stop to the pulse width modulation generator 210, so that the pulse width modulation generator 210 cannot output the pulse width modulation signal. I _PWM .

Please refer to FIG. 6 , which is a schematic diagram of the circuit structure of the fourth embodiment of the LED driving circuit disclosed in the present proposal. The LED driving circuit 100 is a non-isolated LED driving circuit, and includes an input power circuit 102, a LED array 104, a boost converter 106, a feedback resistor 108, and a control circuit 110. The voltage converter 106 includes a power input 107, a power output 109, a switching transistor 60, and an output capacitor 98. The power input terminal 107 is coupled to the input power circuit 102. The power output terminal 109 is coupled to one end of the LED array 104 and the output capacitor 98, and the other end of the output capacitor 98 is grounded. The voltage dividing terminal P is coupled to the control circuit 110, and the control circuit 110 is coupled to the switching transistor 60.

In the present embodiment, the difference between the LED driving circuit 100 and the first embodiment lies in the arrangement position of the feedback resistor 108. One end of the feedback resistor 108 is coupled to the fifty-fourth light emitting diode 20, and the other end of the feedback resistor 108 is coupled to the fifty-fifth light emitting diode 20, and the voltage dividing end point P can be configured in the fiftyth Between the four light-emitting diodes and the feedback resistor 108, this embodiment is not intended to limit the proposal. For example, the voltage dividing terminal P can also be disposed between the feedback resistor 108 and the fifty-fifth LED diode 20 (refer to FIG. 7), which is a light-emitting diode according to the proposal. A circuit configuration diagram of a fifth embodiment of the body drive circuit).

Referring to "Fig. 6" and "Fig. 7", when the input power supply circuit 102 just outputs the current signal I _C , the control circuit 110 is not activated and the boost converter 106 does not start operating, and the current signal I _C is outputted. Capacitor 98 is charged. When the voltage of the output capacitor 98 is greater than the voltage of the LED array 104, the drive signal ID is output to drive the LED array 104. The feedback resistor 108 outputs the feedback signal I _FB to the control circuit 110 according to the driving signal I _D . The feedback signal I _FB is a voltage signal. The LED array 104 provides a starting voltage V _S to the control circuit 110 by the voltage dividing terminal P. When the starting voltage V _{S is} greater than or equal to the operating voltage V _DD of the control circuit 110, the control circuit 110 is based on the feedback signal I. _{The FB} outputs a pulse width modulation signal I _PWM to selectively activate or deactivate the switching transistor 60 to adjust the magnitude of the driving signal I _{D that} drives the LED array 104.

Please refer to FIG. 8 for a circuit configuration diagram of a sixth embodiment of the LED driving circuit disclosed in the present proposal. The LED driving circuit 100 is a non-isolated LED driving circuit, and includes an input power circuit 102, a LED array 104, a boost converter 106, a feedback resistor 108, and a control circuit 110. The voltage converter 106 includes a power input 107, a power output 109, a switching transistor 60, and an output capacitor 98. The power input terminal 107 is coupled to the input power circuit 102. The power output terminal 109 is coupled to one end of the LED array 104 and the output capacitor 98, and the other end of the output capacitor 98 is grounded. The voltage dividing terminal P is coupled to the control circuit 110, and the control circuit 110 is coupled to the switching transistor 60.

In the present embodiment, the difference between the LED driving circuit 100 and the first embodiment lies in the arrangement position of the feedback resistor 108. One end of the feedback resistor 108 is coupled to one end of the first signal I _G outputted by the switch transistor 60 (ie, the source S of the field effect transistor), and the other end of the feedback resistor 108 is grounded.

When the input power circuit 102 has just output the current signal I _C , the control circuit 110 is not activated and the boost converter 106 is not operating, and the current signal I _C charges the output capacitor 98 . When the voltage of the output capacitor 98 is greater than the voltage of the LED array 104, the drive signal I _D is output to drive the LED array 104. The feedback resistor 108 outputs the feedback signal I _FB to the control circuit 110 according to the first signal I _G . The feedback signal I _FB is a voltage signal. The LED array 104 provides a starting voltage V _S to the control circuit 110 by the voltage dividing terminal P. When the starting voltage V _{S is} greater than or equal to the operating voltage V _DD of the control circuit 110, the control circuit 110 outputs a pulse width modulation. The signal I _{PWM is used} to selectively activate or deactivate the switching transistor 60 to adjust the magnitude of the drive signal I _{D that} drives the LED array 104.

According to an embodiment of the LED driving circuit disclosed in the present proposal, it is suitable to drive the LED array. The position of the voltage dividing end of the LED array can be adjusted according to the required operating voltage of the control circuit, so that the LED driving circuit can start the control circuit with different working voltages without having to use the conventional starting circuit. Since the current required to start the control circuit is small, it only accounts for two to five percent of the current required to drive the LED series, so that the conduction of the LED series is not affected. Furthermore, the control circuit has feedback control such that the light-emitting diode is continuously turned on without being affected by temperature.

While the present invention has been disclosed in the foregoing preferred embodiments, it is not intended to limit the present invention. Any skilled person skilled in the art can make some changes and refinements without departing from the spirit and scope of the present proposal. The scope of patent protection of the proposal shall be subject to the definition of the scope of the patent application attached to this specification.

20. . . Light-emitting diode

60. . . Switching transistor

62. . . Second diode

90. . . AC signal source

92. . . Bridge rectifier

94. . . First inductance

96. . . First diode

98. . . Output capacitor

100. . . Light-emitting diode driving circuit

102. . . Input power circuit

104. . . Light-emitting diode series

106. . . Boost converter

107. . . Power input

108. . . Feedback resistor

109. . . Power output

110. . . Control circuit

202. . . Triangle wave generator

204. . . First comparator

2041. . . First positive input

2042. . . Second negative input

2043. . . First output

206. . . Second comparator

2061. . . Second positive input

2062. . . Second negative input

2063. . . Second output

208. . . Voltage sensor

210. . . Pulse width modulation generator

211. . . Zero current detector

212. . . driver

302. . . Second inductance

304. . . Detecting resistance

621, 961. . . Input

622, 962. . . Output

FIG. 1 is a schematic diagram showing the circuit structure of a first embodiment of a light emitting diode driving circuit according to the present proposal.

2 is a schematic diagram showing the circuit structure of a second embodiment of the LED driving circuit disclosed in the present proposal.

Fig. 3 is a circuit diagram showing an embodiment of the control circuit of Fig. 1.

4 is a schematic diagram showing the circuit structure of a third embodiment of the LED driving circuit disclosed in the present proposal.

Fig. 5 is a circuit diagram showing an embodiment of a control circuit of Fig. 4.

Figure 6 is a schematic diagram showing the circuit structure of a fourth embodiment of the LED driving circuit disclosed in the present proposal.

Figure 7 is a schematic diagram showing the circuit structure of a fifth embodiment of the LED driving circuit disclosed in the present proposal.

Figure 8 is a schematic diagram showing the circuit structure of a sixth embodiment of the LED driving circuit disclosed in the present proposal.

20. . . Light-emitting diode

60. . . Switching transistor

62. . . Second diode

90. . . AC signal source

92. . . Bridge rectifier

94. . . First inductance

96. . . First diode

98. . . Output capacitor

100. . . Light-emitting diode driving circuit

102. . . Input power circuit

104. . . Light-emitting diode series

106. . . Boost converter

107. . . Power input

108. . . Feedback resistor

109. . . Power output

110. . . Control circuit

621, 961. . . Input

622, 962. . . Output

Claims (21)

An LED driving circuit includes: an input power circuit for outputting a current signal; a light emitting diode series comprising N light emitting diodes and a voltage dividing end point, the N light emitting diodes The system is coupled in series, and the voltage dividing end is disposed between the kth light emitting diode and the k+1th light emitting diode, wherein N≧2, k+1≦N; one liter The voltage converter includes a switching transistor and an output capacitor, and the boost converter charges the output capacitor according to the current signal. When the voltage of the output capacitor is greater than a voltage required to turn on the LED series, Outputting a driving signal to drive the LED array; a feedback resistor selectively outputting a feedback signal according to the driving signal or a first signal output by the switching transistor, wherein the feedback signal The signal is a voltage signal; and a control circuit, the voltage dividing end is coupled to the control circuit, and the LED array provides a starting voltage to the control circuit by the voltage dividing end point, so that the control circuit is based on The feedback signal outputs a pulse width modulation ( A Pulse Width Modulation (PWM) signal to selectively activate or deactivate the switching transistor, wherein the startup voltage is greater than or equal to an operating voltage of the control circuit. The illuminating diode driving circuit of claim 1, wherein the control circuit comprises: a triangular wave generator for outputting a triangular wave signal; and a first comparator for comparing the feedback signal with a reference voltage And outputting a first comparison signal; a second comparator for comparing the size of the first comparison signal and the triangular wave signal to output a second comparison signal; a voltage sensor for determining the startup voltage Whether it is greater than or equal to the working voltage to selectively output a sensing signal; a pulse width modulation generator that outputs an coincidence signal according to the second comparison signal; and a driver according to the actuation signal The pulse width modulation signal is generated. The illuminating diode driving circuit of claim 1, wherein one end of the feedback resistor is coupled to the boost converter, and the other end of the feedback resistor is coupled to one end of the LED array. The other end of the LED array is grounded. The illuminating diode driving circuit of claim 1, wherein one end of the feedback resistor is coupled to the illuminating diode in series, and the other end of the feedback resistor is grounded. The light-emitting diode driving circuit of claim 1, wherein one end of the feedback resistor is coupled to the kth light-emitting diode, and the other end of the feedback resistor is coupled to the k+1th light-emitting diode In the polar body, the voltage dividing end is selectively disposed between the kth light emitting diode and the feedback resistor or between the feedback resistor and the k+1th light emitting diode. The illuminating diode driving circuit of claim 1, wherein one end of the feedback resistor is coupled to one end of the switching transistor to output the first signal, and the other end of the feedback resistor is grounded. The illuminating diode driving circuit of claim 1, wherein the input power supply circuit comprises an AC signal source and a bridge rectifier, wherein the AC signal source is used for outputting an AC signal, and the bridge rectifier receives the AC signal. The current signal is output. The illuminating diode driving circuit of claim 1, wherein the boosting converter further includes a first inductor and a first diode, and one end of the first inductor is coupled to the input power circuit, the first The other end of the first diode is coupled to an input end of the first diode, and an output end of the first diode is coupled to one end of the output capacitor and the LED, and the other end of the output capacitor Ground. The illuminating diode driving circuit of claim 8, wherein the illuminating diode driving circuit further comprises a second inductor and a detecting resistor, one end of the second inductor is grounded, and the other end of the second inductor is The other end of the detecting resistor is coupled to the control circuit. The illuminating diode driving circuit of claim 9, wherein the control circuit comprises: a triangular wave generator for outputting a triangular wave signal; and a first comparator for comparing the feedback signal with a reference voltage And outputting a first comparison signal; a second comparator for comparing the size of the first comparison signal and the triangular wave signal to output a second comparison signal; a voltage sensor for determining the startup voltage Is it greater than or equal to the working voltage to selectively output a sensing signal; a zero current detector, the second inductor is configured to sense the first inductor and output an inductive signal, and the zero current detector is based on the sensing And outputting a detection signal; a pulse width modulation generator, according to the detection signal, the second comparison signal and the sensing signal output an output signal; and a driver generating the pulse width according to the actuation signal Modulate the signal. The illuminating diode driving circuit of claim 1, wherein the illuminating diode driving circuit further comprises a second diode, the switching transistor is a field effect transistor, and the second diode body is The input end is coupled to a source of the field effect transistor, and an output end of the second diode is coupled to a drain of the field effect transistor, and the control circuit is coupled to a gate of the field effect transistor . The illuminating diode driving circuit of claim 1, wherein the illuminating diode driving circuit further comprises a second diode, the switching transistor is a bipolar junction transistor, and the second diode An input end of the body is coupled to a collector of the bipolar junction transistor, and an output end of the second diode is coupled to an emitter of the bipolar junction transistor, and the control circuit is coupled to the pair The pole is connected to a base of the transistor. An LED driving circuit includes: an input power circuit for outputting a current signal; a light emitting diode series comprising N light emitting diodes and a voltage dividing end point, the N light emitting diodes The system is coupled in series, and the voltage dividing end is disposed between the kth light emitting diode and the k+1th light emitting diode, wherein N≧2, k+1≦N; one liter The voltage converter includes a power input terminal, a power output terminal, a switch transistor, and an output capacitor. The power input terminal is coupled to the input power circuit, and the power output terminal is coupled to the LED array and the An output capacitor, the boost converter charges the output capacitor according to the current signal, and when the voltage of the output capacitor is greater than a voltage required to turn on the LED array, a driving signal is output to drive the LED a feedback resistor, selectively coupled to the LED array, disposed between the LEDs or coupled to the switching transistor, such that the feedback resistor is selectively driven according to the driving a signal or a first signal output by the switch transistor And outputting a feedback signal, wherein the feedback signal is a voltage signal; and a control circuit, the voltage dividing end is coupled to the control circuit, the control circuit is coupled to the switch transistor, and the LED array is Providing a starting voltage to the control circuit by the voltage dividing end, so that the control circuit outputs a Pulse Width Modulation (PWM) signal according to the feedback signal to selectively activate or deactivate the switching power a crystal, wherein the starting voltage is greater than or equal to an operating voltage of the control circuit. The illuminating diode driving circuit of claim 13, wherein the control circuit comprises: a triangular wave generator for outputting a triangular wave signal; and a first comparator comprising a first positive input terminal and a first a first input terminal is coupled to a reference voltage, and the first negative input terminal is coupled to one end of the feedback resistor, so that the first comparator compares the feedback signal with the a first comparison signal is outputted from the reference voltage; a second comparator includes a second positive input terminal, a second negative input terminal and a second output terminal, and the second positive input terminal is coupled to the first An output terminal, the second negative input terminal is coupled to the triangular wave generator, such that the second comparator compares the size of the first comparison signal and the triangular wave signal to output a second comparison signal; a voltage sensor coupled The voltage-dividing end point, the voltage sensor determines whether the starting voltage is greater than or equal to the operating voltage, and selectively outputs a sensing signal; a pulse width modulation generator coupled to the second output terminal and the Voltage sensor, The pulse width modulation generator outputs an coincidence signal according to the second comparison signal and the sensing signal; and a driver coupled to the pulse width modulation generator and the switching transistor, so that the driver is activated according to the The signal produces the pulse width modulated signal. The illuminating diode driving circuit of claim 13, wherein one end of the feedback resistor is coupled to the boost converter, and the other end of the feedback resistor is coupled to one end of the LED array. The other end of the LED array is grounded. The illuminating diode driving circuit of claim 13, wherein one end of the feedback resistor is coupled to the illuminating diode in series, and the other end of the feedback resistor is grounded. The light-emitting diode driving circuit of claim 13, wherein one end of the feedback resistor is coupled to the kth light-emitting diode, and the other end of the feedback resistor is coupled to the k+1th light-emitting diode In the polar body, the voltage dividing end is selectively disposed between the kth light emitting diode and the feedback resistor or between the feedback resistor and the k+1th light emitting diode. The illuminating diode driving circuit of claim 13, wherein one end of the feedback resistor is coupled to one end of the switching transistor for outputting the first signal, and the other end of the feedback resistor is grounded. The illuminating diode driving circuit of claim 13, wherein the boosting converter further includes a first inductor and a first diode, and one end of the first inductor is coupled to the input power circuit, the first The other end of the first diode is coupled to an input end of the first diode, and an output end of the first diode is coupled to one end of the output capacitor and the LED, and the other end of the output capacitor Ground. The illuminating diode driving circuit of claim 19, wherein the illuminating diode driving circuit further comprises a second inductor and a detecting resistor, one end of the second inductor is grounded, and the other end of the second inductor is The other end of the detecting resistor is coupled to the control circuit. The illuminating diode driving circuit of claim 20, wherein the control circuit comprises: a triangular wave generator for outputting a triangular wave signal; a first comparator comprising a first positive input terminal and a first a first input terminal is coupled to a reference voltage, and the first negative input terminal is coupled to one end of the feedback resistor, so that the first comparator compares the feedback signal with the a first comparison signal is outputted from the reference voltage; a second comparator includes a second positive input terminal, a second negative input terminal and a second output terminal, and the second positive input terminal is coupled to the first An output terminal, the second negative input terminal is coupled to the triangular wave generator, such that the second comparator compares the size of the first comparison signal and the triangular wave signal to output a second comparison signal; a voltage sensor coupled The voltage dividing end of the voltage sensor is configured to determine whether the starting voltage is greater than or equal to the working voltage to selectively output a sensing signal; a zero current detector coupled to the detecting resistor, the second Inductance is used to sense the first The inductor outputs an inductive signal, and the zero current detector outputs a detection signal according to the sensing signal; a pulse width modulation generator coupled to the second output terminal, the voltage sensor and the zero current detector The pulse width modulation generator outputs an coincidence signal according to the second comparison signal, the sensing signal and the detection signal; and a driver coupled to the pulse width modulation generator and the switching transistor And causing the driver to generate the pulse width modulation signal according to the actuation signal.