TWI578852B - A system for providing an output current to one or more light emitting diodes - Google Patents

Description

System for providing output current to one or more light emitting diodes

The present invention relates to the field of circuits, and more particularly to a system for providing an output current to one or more light emitting diodes.

At present, the lighting technology of Light-Emitting Diode (LED) has become increasingly mature. LEDs are widely used in the field of lighting to replace traditional incandescent lamps due to their high luminous efficiency and long service life. However, when an LED is used in place of an incandescent lamp, since the LED lamp driving circuit generally does not have an overvoltage protection function or the overvoltage protection accuracy is not high, the LED lamp driving circuit is easily damaged or cannot be efficiently utilized. In order to achieve high-precision overvoltage protection, it is necessary to add complicated peripheral lines in the LED lamp driving circuit, which not only increases the cost, but also causes the printed circuit to be large in size and cannot be directly placed in the lamp head interface.

In view of one or more of the problems described above, the present invention provides a system for providing an output current to one or more light emitting diodes.

A system for providing an output current to one or more light emitting diodes in accordance with an embodiment of the invention includes a switch control element configured to generate a control signal based on information associated with a modulated signal, a demagnetized signal, and a reference signal And using the control signal to control the cut-off and conduction of the system power switch, wherein the system power switch is connected to the first diode terminal of the light-emitting diode and the first inductor terminal of the inductor, and the light-emitting diode is further Including a second diode terminal, the inductor further includes a second inductor terminal, and one or more light emitting diodes The output capacitor is connected in parallel between the second diode terminal and the second inductor terminal.

A method of controlling an output voltage of a system for providing an output current to one or more light emitting diodes according to an embodiment of the present invention, comprising: generating an input voltage detection signal by detecting an input voltage of the system; The duration of the system power switch in the on state, generating a first amount of time; generating a second amount of time by detecting a demagnetization time of the inductor connected to the system power switch; detecting the signal based on the input voltage, the first amount of time, And a second amount of time, calculating a characterization voltage characterizing the output voltage of the system using a predetermined equation dependent on a circuit configuration of the system; and controlling the system power switch to be in an off or normal operating state based on the characterization voltage, thereby controlling the system The output voltage. The normal working state is a state in which the cutoff and conduction of the system power switch are controlled by the pulse width modulation signal.

A system for providing an output current to one or more light emitting diodes according to embodiments of the present invention controls a system power switch by generating a control signal based on information associated with the modulation signal, the demagnetization signal, and the reference signal and utilizing the control signal The cut-off and turn-on provides higher accuracy overvoltage protection. Additionally, the method of controlling the output voltage of the system for providing output current to one or more of the light emitting diodes in accordance with an embodiment of the present invention also provides a more accurate overvoltage protection function.

100, 200, 500‧‧‧ systems for output current

102, 202, 502‧‧‧ AC rectifying elements

104‧‧‧Controller components

106, 208, 508‧‧‧ current output components

V _AC ‧‧‧AC input voltage

V _BULK ‧‧‧ DC voltage

1062‧‧‧System Power Switch

1064, L1‧‧‧Inductors

1066, RS‧‧ ‧ sense resistor

1068, D1‧‧‧ diode

V _OUT ‧‧‧ output voltage

C _OUT ‧‧‧ output capacitor

204, 504‧‧‧resistive voltage dividing components

206, 506‧‧‧Switch control components

202-1‧‧‧First rectifying element terminal

202-2‧‧‧Second rectifier component terminal

202-3, 502-3‧‧‧3rd rectifying element terminal

202-4‧‧‧4th rectifying element terminal

I _L ‧‧‧current waveform flowing through inductor L1

204-1, 504-1‧‧‧First voltage divider terminal

204-2‧‧‧Second voltage divider terminal

204-3‧‧‧ Third voltage divider terminal

VIN‧‧‧First control element terminal

GATE‧‧‧second control element terminal

CS‧‧‧third control element terminal

GND‧‧‧4th control element terminal

208-1‧‧‧First output component terminal

208-2‧‧‧second output component terminal

208-3‧‧‧third output component terminal

208-4‧‧‧fourth output component terminal

208-5‧‧‧5th output component terminal

R1, R2‧‧‧ resistors

K0, K1, K2‧‧‧ switch

V _REF ‧‧‧reference voltage

V _VIN ‧‧‧ voltage signal

L1‧‧‧Inductors

RS‧‧‧Sense Resistors

VDD‧‧‧ chip power supply

VD‧‧‧ is the voltage waveform at the drain of the system power switching MOSFET

Output waveform of Demag‧‧‧ Demagnetization Detection Module

T _ON ‧‧‧System Power Switch MOSFET On Time

T _OFF ‧‧‧System power switching MOSFET cut-off time

T _Demag ‧‧‧Demagnetization time of inductor L1

I _PK ‧‧‧Maximum current value flowing through inductor L1

Output waveform of logic control module after PWM_G‧‧‧PWM signal generation module

SP‧‧‧Sampling pulse signal

V _D ‧‧‧voltage at the drain

C0‧‧‧ capacitor

V _{O_SENSE ‧‧‧Output} signal

The invention can be better understood from the following description of specific embodiments of the invention, in which: FIG. 1 is a conventional system for providing an output current to one or more light-emitting diodes (BUCK circuit) FIG. 2 is a circuit diagram of a system for providing an output current to one or more light emitting diodes according to an embodiment of the present invention; and FIG. 3 is an operational waveform diagram of the system circuit shown in FIG. 2; Figure 4 is a circuit diagram of an Over Voltage Protection (OVP) module in the system circuit shown in Figure 2; Figure 5 is a circuit diagram of a system for providing an output current to one or more light-emitting diodes according to another embodiment of the present invention; Figure 6 is a diagram showing the operation waveforms of the system circuit shown in Figure 5; Figure 7 is a circuit diagram of an overvoltage protection (OVP) module in the system circuit shown in Figure 5.

Features and exemplary embodiments of various aspects of the invention are described in detail below. In the following detailed description, numerous specific details are set forth However, it will be apparent to those skilled in the art that the present invention may be practiced without some of the details. The following description of the embodiments is merely provided to provide a better understanding of the invention. The present invention is in no way limited to any specific configurations and algorithms presented below, but without departing from the spirit and scope of the invention. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessary obscuring the invention.

LED lights are widely used in lighting applications. In order to keep the brightness of the LED lamp constant, a substantially constant current is typically supplied to the LED lamp. Figure 1 is a circuit diagram of a conventional system (BUCK circuit) for providing an output current to one or more light emitting diodes.

As shown in FIG. 1, a system 100 for providing an output current to one or more light emitting diodes includes an AC rectifying element 102, a controller element 104, and a current output element 106. Specifically, the AC rectifying element 102 receives the AC input voltage V _AC and converts the AC input voltage V _AC to a DC voltage V _BULK to provide current to one or more LED lamps. The controller component 104 outputs a control signal to the system power switch 1062 in the current output component 106 via the second control component terminal GATE to control the conduction and deactivation of the system power switch 1062 to regulate the current flowing through the one or more LED lamps ( Or output current). When system power switch 1062 is turned on, the current flowing through inductor 1064 in current output element 106 is sensed by sense resistor 1066 in current output element 106 such that the current sense signal is passed by controller element 104. The three control element terminals CS are received. In response, controller component 104 generates a control signal based on the current sense signal to control the turn-on and turn-off of system power switch 1062. When the system power switch 1062 is turned off, an inductor 1064, a diode 1068, and one or more light emitting diodes connected between the two output terminals of the current output element 106 are formed between the current output element 106. The current loop.

In the system shown in Figure 1, when there is no LED light connected between the two outputs of the current output element 106 (i.e., when the two outputs are open), between the two outputs of the current output element 106 The output voltage V _OUT will be too high, causing the output capacitor C _OUT in the current output element 106 to be easily damaged. Therefore, it is necessary to provide overvoltage protection for the open circuit of the two output terminals of the current output element 106 in the system shown in FIG. However, in the system shown in FIG. 1, the controller component 104 cannot directly measure the output voltage V _OUT between the two output terminals of the current output component 106, and thus cannot accurately control the two outputs of the current output component 106. The output voltage when the terminal is open.

In order to solve one or more problems existing in the system shown in FIG. 1, a method for one or more light emitting diodes according to an embodiment of the present invention, which is described in detail below with reference to FIGS. 2 to 7 is proposed. A system that provides output current.

2 is a circuit diagram of a system for providing an output current to one or more light emitting diodes in accordance with an embodiment of the present invention. As shown in FIG. 2, system 200 for providing an output current to one or more light emitting diodes includes an AC rectifying element 202, a resistive dividing element 204, a switching control element 206, and a current output element 208. The AC rectifying element 202 includes first, second, third, and fourth rectifying element terminals 202-1, 202-2, 202-3, and 202-4. The resistor divider element 204 includes first, second, and third voltage divider component terminals 204-1, 204-2, 204-3. The switch control element 206 includes first, second, third, and fourth control element terminals VIN, GATE, CS, GND. Current output component 208 includes first, second, third, fourth, and fifth output component terminals 208-1, 208-2, 208-3, 208-4, 208-5.

As shown in Fig. 2, the first and second rectifying element terminals 202-1, 202-2 of the AC rectifying element 202 are respectively connected to both ends of an alternating current power source, and the third and fourth rectifying element terminals 202-3, 202- 4 is connected to the first and second voltage dividing element terminals 204-1, 204-2 of the resistor dividing element 204, respectively. The third voltage dividing element terminal 204-3 of the resistance dividing element 204 is connected to the first control element terminal VIN of the switching control element 206. The second control element terminal GATE of the switch control element 206 is connected to the second output element terminal 208-2 of the current output element 208, and the third control element terminal CS is connected to the third output element terminal 208-3 of the current output element 208, The four control element terminals GND are grounded. The first output element terminal 208-1 of the current output element 208 is connected to the first voltage dividing element terminal 204-1 of the resistance dividing element 204, and the fourth output element terminal 208-4 is grounded. An output capacitor C _OUT in current output element 208 is coupled in parallel with one or more light emitting diodes (LEDs) between first output element terminal 208-1 and fifth output element terminal 208-5 of current output element 208 ( The first output element terminal 208-1 and the fifth output element terminal 208-5 are the two output terminals of the current output element 208).

In the system shown in FIG. 2, the AC rectifying element 202 receives the AC input voltage V _AC and rectifies the AC input voltage V _AC to a DC voltage V _BULK to provide a DC current to one or more LEDs. The resistor divider element 204 divides the DC voltage V _BULK through resistors R1 and R2 to generate a voltage signal that enters the switch control element 206. The voltage signal obtained by dividing the DC voltage V _BULK by the resistor voltage dividing element 204 enters the voltage control element via the third voltage dividing element terminal 204-3 of the resistor dividing element 204 and the first control element terminal VIN of the switching control element 206 206. The voltage control element 206 outputs a drive signal to the system power switch MOSFET in the current output element 208 through the second control element terminal GATE to control the system power switch metal oxide semiconductor field effect crystal (Metal-Oxide-Semiconductor Field-Effect Transistor, below Referred to as MOSFET) on and off. When the system power switch MOSFET is turned on, the current flowing through the inductor L1 in the current output element 208 is sensed by the sense resistor RS in the current output element 208 such that the sense current is passed by the switch control element 206 through the third The control element terminal CS is received. In response, switch control component 206 generates a control signal based on information related to the sense current to control the turn-on and turn-off of the system power switch MOSFET. When the system power switch MOSFET is turned off, an inductor L1, a diode D1 in the current output element 208, and one or more light emitting diodes connected between the two output terminals of the current output element 208 are formed. The current loop.

Specifically, as shown in FIG. 2, the gate of the system power switching MOSFET serves as the second output element terminal 208-2 of the current output element 208; the drain of the system power switching MOSFET and the first diode of the diode D1 The terminal is connected to the first inductor terminal of the inductor L1; the second diode terminal of the diode D1 serves as the first output component terminal 208-1 of the current output component 208; and the source of the system power switching MOSFET serves as the current output component a third output element terminal 208-3 of 208, and grounded via a sense resistor RS; a second inductor terminal of inductor L1 as a fifth output element terminal 208-5 of current output element 208; one or more illuminations The pole body is connected in parallel with the output capacitor C _OUT between the first output element terminal 208-1 and the fifth output element terminal 208-5 of the current output element 208.

In this embodiment, as shown in FIG. 2, the switch control component 206 may include an overvoltage protection module, a Pulse Width Modulation (PWM) signal generation module, a logic control module, and a gate. Drive module, demagnetization detection module, and current sensing module. The overvoltage protection module generates an overvoltage protection signal based on a voltage signal from the resistor divider component 204, a demagnetization signal from the demagnetization detection module, and a control signal from the logic control module, and the demagnetization detection module is based on the current output. A current or voltage signal related to the demagnetization condition of the inductor L1 in the component 208 generates a demagnetization signal, and the current sensing module generates a sensing signal based on the sensing current obtained by the sensing resistor RS in the current output component 208, the PWM signal The generating module generates a pulse width modulation signal based on the demagnetization signal and the sensing signal, and the logic control module performs a logic operation to generate a control signal based on the pulse width modulation signal and the overvoltage protection signal, and the gate driving module generates a driving signal based on the control signal. Used to control the turn-on and turn-off of the system power switching MOSFET in the current output component 208. When the system power switching MOSFET in current output component 208 is in a normal operating state, its turn-off and turn-on are controlled by a pulse width modulation signal (PWM) to control and regulate the current flowing through one or more of the light emitting diodes.

Fig. 3 is a diagram showing the operation waveforms in the system circuit shown in Fig. 2. In Fig. 3, the PWM_G waveform is the output waveform of the logic control module after the PWM signal generation module, the gate (GATE) waveform is the output waveform of the gate drive module, and the I _L waveform is flowing through the inductor L1. The current waveform, the VD waveform is the voltage waveform at the drain of the system power switching MOSFET, and the Demag waveform is the output waveform of the demagnetization detection module. T _ON is the duration in which the system power switching MOSFET is in an on state (ie, the on-time of the system power switching MOSFET), and T _OFF is the duration in which the system power switching MOSFET is in an off state (ie, the off time of the system power switching MOSFET), T _Demag is the demagnetization time of inductor L1, and T _{Demag is} less than T _OFF .

In the system shown in FIG. 2, when the output voltage of the second control element terminal GATE of the switch control element 206 is at a high level (ie, the GATE waveform in FIG. 3 is logic high), the current output element 208 is The system power switch MOSFET is turned on, and the current flowing through the inductor L1 in the current output element 208 rises linearly (the current value flowing through the inductor L1 can be obtained according to the formula (1)). In the current output element 208, the current flowing through the inductor L1 flows through the sense resistor RS to ground through the system power switching MOSFET, and the voltage value generated on the sense resistor RS (ie, at the switch control element 206) The voltage value sensed at the three control element terminals CS is V _CS ) and can be derived from equation (2). When V _CS reaches the set value or T _ON reaches the set value, the output voltage of the second control element terminal GATE of the switch control element 206 becomes a low level (ie, the GATE waveform in FIG. 3 becomes a logic low), the current The system power switch MOSFET in output element 208 is turned off. At this time, the inductor L1 in the current output element 208 is demagnetized by the diode D1, the one or more light emitting diodes, and the output capacitor C _OUT , and the current flowing through the inductor L1 after the demagnetization is completed after the T _Demag time. Becomes zero. The switch control element 206 can determine the demagnetization start point and the end point of the inductor L1 by detecting the current flowing through the inductor L1 in the current output element 208, thereby obtaining the demagnetization time T _Demag (demagnetization can be obtained according to the formula (3) Time, where I _PK is the maximum current value flowing through inductor L1). Further, since the circuit system shown in Fig. 2 is essentially an improvement of the BUCK circuit, the relationship between the output voltage V _OUT and the DC voltage V _BULK outputted from the AC rectifying element 202 is as shown in the formula (4).

That is, based on the information of the voltage V _BULK output by the AC rectifying element 202, the on-time T _{ON of the} system power switching MOSFET, and the demagnetization time T _Demag of the inductor L1, the output voltage V can be calculated by the equation (4). _OUT .

Figure 4 is a circuit diagram of an overvoltage protection (OVP) module in the system circuit shown in Figure 2. As shown in FIG. 4, the overvoltage protection module includes switches K1, K2, a low pass filter, and a comparator. Wherein, the switch K1 is connected between the third voltage dividing element terminal 204-3 of the resistance voltage dividing element 204 and the first filter terminal of the low pass filter, and the switch K2 is connected to the first filter terminal of the low pass filter and Between ground, the low pass filter further includes a second filter terminal, the second filter terminal being coupled to the first comparator terminal of the comparator, the comparator further comprising a second comparator terminal, the second comparator terminal The logic control module provides an overvoltage protection signal.

In the overvoltage protection module shown in FIG. 4, when PWM_G is at a high level and the system power switch MOSFET in the current output element 208 is turned on, the switch K1 is turned on, and the DC voltage V _BULK outputted by the AC rectifying element 202 passes. A voltage signal generated by voltage division of the resistors R1, R2 in the resistor divider element 204 is input to a low pass filter. During the period in which the system power switching MOSFET in the current output element 208 is turned off to the end of the demagnetization of the inductor L1 (i.e., within T _Demag ), the switch K1 is turned off, the switch K2 is turned on, and the ground signal is input to the low pass filter. During the other time periods, switches K1 and K2 are not conducting. The low pass filter smooth filters the voltage signal from the resistor divider element 204 and outputs a substantially DC voltage signal. Here, the switches K1 and K2 may be, for example, a Complementary Metal-Oxide-Semiconductor (CMOS) switch.

The system shown in Fig. 2 detects the V _BULK by the resistors R1 and R2 in the resistor divider element 204 and combines the calculations of T _ON and T _Demag to obtain the actual output voltage value V _OUT . Specifically, the voltage signal V _VIN of the overvoltage protection module entering the first control element terminal VIN via the switch control element 206 is shown by the formula (5), and the output signal V of the low pass filter shown in FIG. _{O_SENSE} is derived from equation (6). Combining equations (4)-(6), the relationship between V _{O_SENSE} and V _OUT shown in equation (7) can be obtained.

When V _{O_SENSE is} higher than a predetermined reference voltage V _REF (ie, V _OUT > × V _REF ), the system shown in Fig. 2 can recognize that the output voltage V _OUT has an overvoltage condition, so the switch control element 206 controls the output of the second control element terminal GATE to turn off the system power switch MOSFET (off) The energy transfer to the output of the current output element 208 is immediately cut off, thereby achieving high precision overvoltage protection.

Figure 5 is a circuit diagram of a system for providing an output current to one or more light emitting diodes in accordance with another embodiment of the present invention. As shown in FIG. 5, the system 500 for supplying an output current to one or more light-emitting diodes is substantially the same as the system circuit shown in FIG. 2 except for the following two points: (1) Resistive voltage dividing element 504 The first voltage dividing element terminal 504-1 is connected to the drain of the system power switching MOSFET in the current output element 508 instead of the third rectifying element terminal 502-3 of the alternating current rectifying element 502; (2) the switching control element 506 is Including an overvoltage protection module, a pulse width modulation (PWM) signal generation module, a logic control module, a gate drive module, a demagnetization detection module, and a current sensing module, and a sampling pulse module.

In this embodiment, as shown in FIG. 5, the overvoltage protection module is based on a voltage signal from the resistor divider element 504, a demagnetization signal from the demagnetization detection module, a sample pulse signal SP from the sampling pulse module, and The control signal from the logic control module generates an overvoltage protection signal, and the demagnetization detection module generates a demagnetization signal based on a current or voltage signal related to the demagnetization condition of the inductor L1 in the current output component 508, and the sampling pulse module generates a demagnetization signal based on the demagnetization signal. a sampling pulse signal SP having a duration of a high level that is less than a duration of a high level of the demagnetization signal, the current sensing module generating a sensing signal based on the sensing current obtained by the sensing resistor RS in the current output element 508, The PWM signal generating module generates a pulse width modulation signal based on the demagnetization signal and the sensing signal, and the logic control module performs a logic operation to generate a control signal based on the pulse width modulation signal and the overvoltage protection signal, and the gate driving module generates the control signal based on the control signal. The drive signal is used to control the turn-on and turn-off of the system power switch MOSFET in current output component 508. When the system power switching MOSFET in current output component 508 is in a normal operating state, its turn-off and turn-on are controlled by a pulse width modulation signal (PWM) to control and regulate the current flowing through one or more of the light emitting diodes.

In the system circuit shown in FIG. 5, when the system power switch MOSFET in the current output element 508 is turned on, the voltage V _D at the drain of the system power switch MOSFET is close to zero; when the system in the current output element 508 When the power switch MOSFET is turned off, the voltage V _D at the drain of the system power switching MOSFET is close to the DC voltage V _BULK (V _D = V _BULK + V _D1 , which is obtained by rectifying the AC input voltage V _AC by the AC rectifying element 502, V _D1 is the forward voltage of the diode _D1 in the current output element 508, for example, about 1V).

Fig. 6 is a diagram showing the operation waveforms in the system circuit shown in Fig. 5. In Fig. 6, the PWM_G waveform is the output waveform of the logic control module after the PWM signal generation module, and the GATE waveform is the output waveform of the gate drive module (ie, the second control element terminal GATE of the switch control element 506). The I _L waveform is the current waveform flowing through the inductor L1, the VD waveform is the voltage waveform at the drain of the system power switching MOSFET, the Demag waveform is the output waveform of the demagnetization detecting module, and the SP waveform is the output waveform of the sampling pulse module. . T _ON is the duration of the system power switching MOSFET in the on state, T _OFF is the duration of the system power switching MOSFET in the off state, T _Demag is the demagnetization time of the inductor L1, and T _{Demag is} less than T _OFF . The sampling pulse signal SP outputted by the sampling pulse module is at a high level for a duration Tsp smaller than the demagnetization time T _{Demag of the} inductor L1 to ensure that the sampling ends within the demagnetization period.

Figure 7 is a circuit diagram of an overvoltage protection (OVP) module in the system circuit shown in Figure 5. As shown in FIG. 7, the overvoltage protection module includes a switch K0, a capacitor C0, a buffer, switches K1, K2, a low pass filter, and a comparator. Wherein, the switch K0 is connected between the third voltage dividing element terminal 504-3 of the resistor dividing element 504 and the first buffer terminal of the buffer, and the capacitor C0 is connected between the first buffer terminal of the buffer and the ground. The buffer further includes a second buffer terminal, the switch K1 being coupled between the second buffer terminal of the buffer and the first filter terminal of the low pass filter, the switch K2 being coupled to the first filter terminal of the low pass filter Between ground and ground, the low pass filter further includes a second filter terminal, the second filter terminal is coupled to the first comparator terminal of the comparator, the comparator further includes a second comparator terminal, and the second comparator terminal is logic The control module provides an overvoltage protection signal.

In the overvoltage protection module shown in FIG. 7, the sampling pulse signal SP supplied to the switch K0 is high level from the time when the system power switching MOSFET in the current output element 508 is turned off until the end of the demagnetization of the inductor L1. The voltage V _D at the drain of the system power switching MOSFET in the current output element 508 is sampled to the capacitor C0 via the voltage division generated by the voltage divider of the resistors R1, R2 in the resistor divider element 504; at the sampling pulse signal SP When low, the voltage of capacitor C0 is maintained. Here, the buffer can be, for example, an analog voltage follower.

In addition, when PWM_G is high and the system power switch MOSFET in current output element 508 is on, switch K1 is turned on and the output of the buffer is connected to the input of the low pass filter. During the end of the system power switching MOSFET in current output element 508 to the end of demagnetization of inductor L1, switch K1 is turned off, switch K2 is turned on, and the ground signal is input to the low pass filter. During the other time periods, switches K1 and K2 are not conducting. Low pass filter pair input The signal to it is smoothed and outputs a voltage signal that approximates DC. The switch K0, the switches K1, and K2 may be, for example, CMOS switches.

The system shown in Figure 5 detects V _D through resistors R1, R2 in resistor divider element 504 (during the demagnetization of inductor L1 in current output component 508, V _D = V _BULK + V _D1 , approximately V _BULK ) Combined with calculations such as T _ON and T _Demag , the actual output voltage V _OUT can be obtained. Here, V _{O_SENSE} output by the low-pass filter is approximated by equation (8):

When V _{O_SENSE is} higher than a predetermined reference voltage V _REF (ie, V _OUT > × V _REF ), the system shown in Fig. 5 can recognize that the output voltage V _OUT has an overvoltage condition, so the switch control element 506 controls the output of the second control element terminal GATE to turn off the system power switch MOSFET (off) The energy transfer to the output of the current output element 508 is immediately cut off, thereby achieving high-precision overvoltage protection.

Those skilled in the art will appreciate that there are many more alternative embodiments and improvements that can be used to implement the embodiments of the present invention, and that the above-described embodiments and examples are merely illustrative of one or more embodiments. Therefore, the scope of the invention is limited only by the scope of the appended claims.

V _BULK ‧‧‧ DC voltage

K1, K2‧‧‧ switch

R1, R2‧‧‧ resistors

V _REF ‧‧‧reference voltage

VIN‧‧‧First control element terminal

V _{O_SENSE ‧‧‧Output} signal

Output waveform of logic control module after PWM_G‧‧‧PWM signal generation module

Overvoltage protection in OVP‧‧‧ system circuits

Output waveform of Demag‧‧‧ Demagnetization Detection Module

Claims (6)

A system for providing an output current to one or more light emitting diodes, comprising: a switch control element configured to generate a control signal based on information associated with a pulse width modulation signal, a demagnetization signal, and a reference signal, and Using the control signal to control off and on of the system power switch; the AC rectifying element configured to rectify the AC signal from the AC power source to generate a rectified signal; the resistor divider element configured to perform the rectified signal Dividing to generate a voltage signal into the switching control element; wherein the system power switch is coupled to a first diode terminal of the diode and a first inductor terminal of the inductor, the diode further The second diode terminal is included, the inductor further includes a second inductor terminal, and the one or more light emitting diodes are connected in parallel with the output capacitor at the second diode terminal and the second Between the inductor terminals; wherein the AC rectifying element includes first, second, third, and fourth rectifying element terminals, the first and second rectifying The terminal terminals are respectively connected to both ends of the alternating current power source, and the third and fourth rectifier component terminals are respectively connected to the first and second voltage dividing component terminals of the resistor voltage dividing component, wherein the fourth rectifier component The terminal is further connected to the ground, the resistor voltage dividing element further comprising a third voltage dividing component terminal, the third voltage dividing component terminal providing the switching control component with the voltage signal entering the switching control component; wherein The switch control element includes a first control element switch, a second control element switch, a low pass filter, and a comparator, the first control element switch being coupled to the third voltage dividing element of the resistance voltage dividing element Between the terminal and the first filter terminal of the low pass filter, the second control element switch is coupled between the first filter terminal of the low pass filter and ground, the low pass filtering The device also includes a second filter terminal coupled to the first comparator terminal of the comparator, the comparator further including a second comparator terminal, the second comparator terminal The system power switch provides the control signal; wherein said first switching control element is turned to a high level state in the control signal And in an off state when the control signal is low, the second control element switch is in an on state when the demagnetization signal is at a high level, and is in an off state when the demagnetization signal is at a low level. A system for providing an output current to one or more light emitting diodes, comprising: a switch control element configured to generate a control signal based on information associated with a pulse width modulation signal, a demagnetization signal, and a reference signal, and Using the control signal to control off and on of the system power switch; the AC rectifying element configured to rectify the AC signal from the AC power source to generate a rectified signal; the resistor divider element configured to perform the rectified signal Dividing to generate a voltage signal into the switching control element; wherein the system power switch is coupled to a first diode terminal of the diode and a first inductor terminal of the inductor, the diode further The second diode terminal is included, the inductor further includes a second inductor terminal, and the one or more light emitting diodes are connected in parallel with the output capacitor at the second diode terminal and the second Between the inductor terminals; wherein the AC rectifying element includes first, second, third, and fourth rectifying element terminals, the first and second rectifying The terminal terminals are respectively connected to both ends of the alternating current power source, and the third and fourth rectifying element terminals respectively correspond to the second diode terminal of the diode and the second portion of the resistor dividing component The pressing element terminal is connected, the fourth rectifying element terminal is further connected to the ground, the resistive voltage dividing element further includes a first voltage dividing element terminal and a third voltage dividing component terminal, wherein the first voltage dividing element terminal and The first diode terminal of the diode and the drain connection of the system power switch, the third voltage dividing component terminal providing the switch control element with the entry into the switch control element a voltage signal; wherein the switch control element includes a first control element switch, an element capacitor, a buffer, a second control element switch, a third control element switch, a low pass filter, and a comparator, the first control element a switch connected between the third voltage dividing component terminal of the resistor voltage dividing element and a first buffer terminal of the buffer, the component capacitor being connected to the buffer Between the first buffer terminal and the ground, the buffer further includes a second buffer terminal, the second control element switch being connected to the second buffer terminal of the buffer and the low Between the first filter terminals of the pass filter, the third control element switch is coupled between the first filter terminal of the low pass filter and ground, and the low pass filter further includes a second a filter terminal, the second filter terminal being coupled to a first comparator terminal of the comparator, the comparator further comprising a second comparator terminal, the second comparator terminal providing the system power switch The control signal; wherein the switch control element is further configured to generate a sampling signal according to the demagnetization signal, wherein the sampling signal is at a high level for a duration that is less than a duration of the demagnetization signal being at a high level, The first control element switch is in an on state when the sampling signal is at a high level, and is in an off state when the sampling signal is at a low level, and the second control element switch is in the pulse width modulation When the number is high, it is in an on state, and when the pulse width modulation signal is low, it is in an off state, and the third control element switch is in an on state when the demagnetization signal is at a high level, and in the When the demagnetization signal is low, it is in the off state. The system of claim 2, wherein the demagnetization signal is at a high level for a duration that is less than a duration of the pulse width modulation signal being at a low level. A method of controlling an output voltage of a system for providing an output current to one or more light emitting diodes, comprising: generating an input voltage detection signal by detecting an input voltage of the system; by detecting system power in the system a duration of the switch in an on state, generating a first amount of time; generating a second amount of time by detecting a demagnetization time of the inductor connected to the system power switch; detecting the signal based on the input voltage, the first amount of time And the second amount of time, calculating the output voltage of the system using a predetermined equation: Wherein V _OUT is the output voltage of the system, V _BULK is the DC input voltage obtained by rectifying the AC input voltage by the system, and T _ON is the first time representing the duration of the system power switch being in the on state. The amount of time, T _{Dmeag ,} is the second amount of time representative of the demagnetization time of the inductor. A method of controlling an output voltage of a system for providing an output current to one or more light emitting diodes, comprising: generating an input voltage detection signal by detecting an input voltage of the system; by detecting system power in the system a duration of the switch in an on state, generating a first amount of time; generating a second amount of time by detecting a demagnetization time of the inductor connected to the system power switch; detecting the signal based on the input voltage, the first amount of time And the second amount of time, calculating a characterization voltage characterizing an output voltage of the system using a predetermined equation dependent on a circuit configuration of the system; and controlling the system power switch to be off or according to the characterization voltage a normal operating state, thereby controlling an output voltage of the system, the normal operating state being a state in which the cutoff and conduction of the system power switch are controlled by a pulse width modulation signal; wherein the characterized voltage is calculated using the following equation: Wherein, V _{O_SENSE} is the characteristic voltage, V _VIN is a voltage value representing the input voltage detection signal, and T _ON is the first time amount representing a duration of the system power switch being in an on state, T _Dmeag is The second amount of time representative of the demagnetization time of the inductor. The method of claim 5, wherein if the characterization voltage is higher than a predetermined voltage, controlling the system power switch to be in an off state, otherwise controlling the system power switch to be in a normal operating state.