Drive apparatus for semiconductor light-emitting device, and illumination device

Abstract

A drive apparatus for driving a semiconductor light-emitting device. The drive apparatus comprises an input interface, which is used for connecting to a mains input; and an output interface, which is connected in series to a linear drive circuit and is used for connecting to a semiconductor light-emitting device by means of the linear drive circuit. The drive apparatus further comprises: a mains frequency and voltage regulation circuit, which is coupled between the input interface and the linear drive circuit, and is used for performing power conversion at a mains frequency and changing the voltage amplitude of the mains input, which is provided to the linear drive circuit, wherein the mains frequency and voltage regulation circuit comprises a capacitor that is used for charging and discharging at the mains frequency; a detection circuit, which is used for detecting a signal related to the voltage of the mains input; and a control circuit, which is used for selectively activating or deactivating the mains frequency and voltage regulation circuit on the basis of the signal detected by the detection circuit.

Description

Driving device of semiconductor light emitting device and lighting equipment TECHNICAL FIELD

[0001] The present application belongs to the field of lighting technology, and particularly relates to a driving device of semiconductor light emitting equipment and a lighting equipment. BACKGROUND

[0002] Compared with the driving device of semiconductor light emitting equipment based on switching power supply, the driving device based on linear driving technology has many advantages, such as simpler design, fewer components, less EMI (electromagnetic interference), lower audible noise, etc. However, the linear driving technology also has obvious disadvantages, that is, relatively large power consumption, in other words, relatively low efficiency. The main reason is that the linear driving technology needs to generate a certain voltage drop on the linear driving tube (BJT, MOSFET, etc.) to ensure that the linear driving tube can perform linear current regulation, so the power consumption of the linear driving tube is equal to the voltage drop multiplied by the driving current.

[0003] Fig. 1 shows a circuit of a typical linear driving technology, in which AC indicates AC power input, DB is a diode bridge, El_cap is a large-capacitance electrolytic capacitor, which provides a buffered bus voltage on the bus DC_bus. The linear driving tube is Q1, which is a MOS tube connected in series with the LED load. The resistor R1 detects the LED current, and the negative input of the operational amplifier U1 collects the LED current detected by R1, compares it with the reference value Ref of the positive input of the operational amplifier, and outputs a corresponding voltage to the gate of the linear driving tube Q1, so as to stabilize the driving current of the linear driving tube Q1 in the required size in the form of negative feedback. Among them, the difference between the bus voltage and the on-voltage V_LED of the LED load is loaded on the linear driving tube Q1 and the detection resistor R1, and the resistance of the detection resistor R1 is very small, so the difference between the bus voltage and the on-voltage V_LED of the LED load can be approximately considered to be loaded on the linear driving tube Q1. Generally speaking, when the linear driving switch works in the linear mode to regulate the current, it only needs a certain voltage between its two ends, which is called minimum headroom. If the voltage between its two ends is greater than this voltage, the linear driving switch can normally regulate the current, but it will produce useless power consumption.

[0004] Generally, the root mean square value of the mains input is ideally 220V. However, due to different actual environments, the root mean square value of the mains input can actually deviate from 220V, for example, from 210V to 250V. The electrical appliance must be designed to allow for these deviations, i.e. the electrical appliance must be operable at all values within the range of the mains input deviation, so the design of the general electrical appliance should meet the lower limit of the deviation range. However, this will cause power consumption problems in the linear drive technology. As shown in Figure 2, which shows the DC-BUS bus voltage under the condition of mains input corresponding to different root mean square values. For example, the driving device is designed to meet the lower limit of the mains input, i.e. 210V, at which the minimum value of the DC-BUS bus voltage is approximately 290V (210V x 1.414). The LED voltage is approximately 275V, which can generate a voltage difference of about 15V on the linear drive tube MOS to ensure that the linear drive tube MOS operates in linear mode to control the LED current. However, the same driving device can also be driven by a mains input with a higher root mean square value, and the corresponding bus voltage DC-BUS is shown as 230Vac and 250Vac in the figure. As can be seen, in these cases, the bus voltage increases, and the voltage difference between the bus voltage and the LED voltage increases, which will cause the power consumption on the linear drive tube to increase. In summary, the efficiency of the driving device is only about 80% under various possible mains inputs.

[0005] There is prior art as shown in Figure 3, which uses a constant voltage buck module based on a switching power supply, for example, to convert the input voltage to convert input voltages of different root mean square values into a substantially same bus voltage to match the LED turn-on voltage. For example, when the root mean square value of the input mains is high, the constant voltage buck module is activated; when the root mean square value of the input mains is appropriate, the constant voltage buck module is deactivated. However, the introduction of the switching power supply also brings problems such as increased cost, increased EMI interference, increased audible noise, etc.

[0006] Practical new type content

[0007] The purpose of the present application is to provide a driving device for a semiconductor light emitting device and a lighting device comprising the driving device and the semiconductor light emitting device. The inventive concept of the present application is to use a mains frequency voltage regulation circuit for power conversion at a mains frequency in a driving device based on linear drive technology, and selectively activate or deactivate the voltage regulation circuit according to the voltage of the mains input, to regulate the driving voltage finally given to the linear drive circuit.

[0008] According to one basic aspect of the present application, a driving device for driving a semiconductor light emitting device is provided, comprising an input interface for connecting to a mains input; and an output interface connected in series with a linear driving circuit and for connecting to the semiconductor light emitting device through the linear driving circuit; characterized in that further comprising a mains frequency voltage regulating circuit coupled between the input interface and the linear driving circuit, for performing power conversion at a mains frequency and changing the voltage amplitude of the mains input provided to the linear driving circuit, the mains frequency voltage regulating circuit comprising a capacitor for charging and discharging at the mains frequency; a detection circuit for detecting a signal related to the voltage of the mains input; and a control circuit for selectively activating or deactivating the mains frequency voltage regulating circuit according to the signal detected by the detection circuit.

[0009] In this basic aspect, the driving voltage obtained by the linear driving circuit is not affected by the change of the voltage of the mains input, so that the voltage drop of the linear driving circuit is ensured to be within a high efficiency range, the overall efficiency of the driving device is improved, and the power consumption is reduced. Moreover, the mains frequency voltage regulating circuit also has the advantages of low cost, low EMI and low audible noise.

[0010] In a further embodiment, the mains frequency voltage regulating circuit comprises a mains frequency voltage boosting circuit, and the control circuit is configured to: deactivate the mains frequency voltage boosting circuit when the signal indicates that the voltage of the mains input is greater than a certain threshold; and activate the mains frequency voltage boosting circuit when the signal indicates that the voltage of the mains input is less than the certain threshold.

[0011] This embodiment provides an adjustment mode, which can boost the voltage when the mains input voltage is too low, and does not boost the voltage when the mains input voltage is appropriate, so as to ensure that the driving voltage provided to the linear driving circuit is not affected by the change of the mains input.

[0012] In a further embodiment, the detection circuit is configured to detect a signal related to the average or peak value of the voltage of the mains input, and the mains frequency voltage boosting circuit comprises a half-wave or full-wave charge pump voltage boosting circuit, and the capacitor comprises a charge pump capacitor. The charge pump voltage boosting circuit is simple to implement, requires fewer components, and is relatively simple to control. Charge pumps generally operate in half-wave or full-wave mode, so it is appropriate to activate or deactivate the charge pump according to the half-wave or full-wave average or peak value of the voltage of the mains input.

[0013] In one embodiment, the driving device comprises a rectifier bridge connected between the input interface and the linear driving circuit; the charge pump capacitor is connected between the input interface and the negative input of the rectifier bridge, and is used to be charged when the mains input is in a first polarity and to be boosted by the mains input when the mains input is in a second polarity. This embodiment provides a more specific implementation of the charge pump type boost circuit.

[0014] In one embodiment, the control circuit comprises a switch connected in series with the charge pump capacitor between the input interface and the negative input of the rectifier bridge, and is used to open the switch to deactivate the mains frequency boost circuit and to close the switch to activate the mains frequency boost circuit.

[0015] In this embodiment, the deactivation or activation of the charge pump boost circuit is controlled by opening and closing the switch connected in series with the charge pump capacitor, which is very simple to implement.

[0016] As an alternative to the above mains frequency boost circuit, the mains frequency voltage regulation circuit comprises a mains frequency step-down circuit, and the control circuit is used to activate the mains frequency step-down circuit when the signal indicates that the average or peak value of the voltage of the mains input is greater than a certain threshold, and to deactivate the mains frequency step-down circuit when the signal indicates that the average or peak value of the voltage of the mains input is less than the certain threshold.

[0017] This embodiment provides an alternative adjustment method, which can step down when the mains input voltage is too high and does not step down when the mains input voltage is appropriate, ensuring that the driving voltage provided to the linear driving circuit is not affected by the change of the mains input.

[0018] In a further embodiment, the mains frequency step-down circuit comprises a capacitive step-down circuit, which comprises a step-down capacitor connected in series between the input interface and the linear driving circuit.

[0019] This embodiment provides a relatively simple and easy-to-implement implementation.

[0020] In a further embodiment, the control circuit comprises a bypass branch connected in parallel with the capacitive step-down circuit; the control circuit is used to close the bypass branch to deactivate the capacitive step-down circuit and to open the bypass branch to activate the capacitive step-down circuit.

[0021] This embodiment selects deactivation or activation by bypassing or not bypassing the capacitive step-down circuit, which is relatively simple to implement.

[0022] In a further embodiment, the driving device further comprises a smoothing capacitor connected in parallel with the linear driving circuit and the output interface, and the control circuit is configured to: when the driving device is just starting from a power-off state and / or the voltage on the smoothing capacitor is below a certain threshold, deactivate the step-down circuit regardless of the signal detected by the detection circuit; and after the driving device is stable after starting from the power-off state and / or the voltage on the smoothing capacitor is below the certain threshold, selectively activate or deactivate the mains frequency voltage regulation circuit according to the signal detected by the detection circuit.

[0023] The problem solved by this embodiment is that when the voltage of the starting capacitor or the smoothing capacitor is too low, the step-down circuit may bear a voltage beyond its step-down capability. Therefore, this embodiment proposes that when the voltage of the starting capacitor or the smoothing capacitor is too low, the step-down circuit is not started immediately, and after the smoothing capacitor is charged to a certain extent, the step-down circuit starts to work normally, so that the voltage borne by the step-down circuit can be kept within its capability range, and the step-down circuit will not be affected.

[0024] In a specific embodiment, a feedforward or open-loop mode is used to control the activation or deactivation of the voltage regulation circuit. Specifically, the detection circuit comprises a first voltage detection circuit connected to the input interface and directly detecting the signal indicative of the mains input to obtain a first signal related to the average or peak or instantaneous value of the voltage thereof.

[0025] The advantage of this specific embodiment is that the feedforward or open-loop implementation is relatively simple.

[0026] In a more specific embodiment, the first voltage detection circuit comprises a peak detection circuit, and the control circuit comprises a comparator configured to receive a first reference signal and the first signal, the first reference signal corresponding to a threshold value of the average or peak value of the voltage of the mains input.

[0027] In a more specific embodiment, the driving device further comprises a first reference signal generation circuit configured to:

[0028] generate a fixed first reference signal; or

[0029] generate a variable first reference signal.

[0030] In this embodiment, generating a fixed first reference signal is relatively simple to implement. Generating a variable first reference signal has better flexibility and can achieve more functions.

[0031] In particular, the first reference signal generating circuit generates a variable first reference signal according to the voltage drop across the linear driving circuit, which is a negative feedback to make the voltage drop across the linear driving circuit lower, so as to improve the efficiency of the linear driving circuit.

[0032] More particularly, when the mains frequency voltage regulating circuit comprises a mains frequency step-up circuit, the first reference signal when the voltage drop across the linear driving circuit is greater than the second threshold is lower than the first reference signal when the voltage drop across the linear driving circuit is less than the second threshold. The principle of doing so is that when the voltage drop across the linear driving circuit is greater than the second threshold, the power consumption of the linear driving circuit is greater, so a smaller first reference signal can be provided to make the mains frequency step-up circuit deactivate at a lower voltage condition to reduce the voltage output to the linear driving circuit and thus reduce its power consumption.

[0033] More particularly, when the mains frequency voltage regulating circuit comprises a mains frequency step-up circuit, the first reference signal when the voltage drop across the linear driving circuit is greater than the second threshold is lower than the first reference signal when the voltage drop across the linear driving circuit is less than the second threshold. The principle of doing so is that when the voltage drop across the linear driving circuit is greater than the second threshold, the power consumption of the linear driving circuit is greater, so a smaller first reference signal can be provided to make the mains frequency step-up circuit deactivate at a lower voltage condition to reduce the voltage output to the linear driving circuit and thus reduce its power consumption.

[0034] As an alternative to the aforementioned feedforward implementation, a closed-loop feedback control can be employed to control the activation or deactivation of the voltage regulating circuit. In particular, the detection circuit comprises a second voltage detection circuit connected to the linear driving circuit for detecting the voltage across the linear driving circuit as a second signal, which is indicative of the average or peak or instantaneous value of the mains input voltage.

[0035] The advantage of the closed-loop feedback control is that it is more accurate. For example, when the voltage across the linear driving circuit is too high, the step-down circuit is activated to step down the voltage; or when the voltage across the linear driving circuit is too low, the step-up circuit is activated to step up the voltage.

[0036] The second aspect of the present application provides an integrated circuit controller for the aforementioned driving device, which integrates the detection circuit and the control circuit.

[0037] A third aspect of the present application provides an integrated circuit for driving LEDs, comprising an integrated circuit controller according to the second aspect above, and a linear driver circuit coupled to the input interface for converting the mains input from the input interface into a driving current.

[0038] A fourth aspect of the present application provides a lighting device based on semiconductor light emitting devices, comprising a semiconductor light emitting device, and an integrated circuit for driving LEDs according to the third aspect above. Preferably, the semiconductor light emitting device comprises a light emitting diode (LED) or a laser diode. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0040] Fig. 1 is a circuit of a prior art linear driving technique;

[0041] Fig. 2 shows the internal working voltage of the circuit of the prior art linear driving technique for different root mean square values of the mains input;

[0042] Fig. 3 shows a circuit diagram for solving the technical problem in Fig. 2 by using a switching power supply;

[0043] Fig. 4 shows a circuit diagram according to one embodiment of the present application;

[0044] Fig. 5 shows the internal working voltage of the circuit according to the embodiment of Fig. 4 for different root mean square values of the mains input;

[0045] Fig. 6 shows a circuit diagram according to another embodiment of the present application; and

[0046] Fig. 7 shows an improved embodiment of the embodiment of Fig. 4. DETAILED DESCRIPTION

[0047] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0048] One of the most basic embodiments of the present application provides a driving device for driving semiconductor light emitting devices, comprising

[0049] - an input interface for connecting to an AC mains input;

[0050] - an output interface in series with a linear drive circuit and for connecting to the semiconductor light emitting device;

[0051] characterized in that it further comprises

[0052] - a mains frequency voltage regulation circuit coupled between the input interface and the linear drive circuit for power conversion at mains frequency and for varying the voltage amplitude of the mains input provided to the linear drive circuit, the mains frequency voltage regulation circuit comprising a capacitor for charging and discharging at mains frequency;

[0053] - a detection circuit for detecting a signal related to the voltage of the mains input;

[0054] - a control circuit for selectively activating or deactivating the mains frequency voltage regulation circuit depending on the signal detected by the detection circuit.

[0055] Preferably, the driving device is integrated in an integrated circuit. More preferably, the integrated circuit further integrates the linear drive circuit coupled to the input interface for converting the mains input from the input interface into a driving current. Alternatively, an external linear drive circuit is also possible.

[0056] Figure 4 shows a circuit diagram of a preferred embodiment of the application. In this embodiment, the mains frequency voltage regulation circuit is implemented by a mains frequency boost circuit. The control circuit deactivates the mains frequency boost circuit when the signal indicates that the average or peak value of the voltage of the mains input is greater than a certain threshold (e.g. the first reference signal Ref2), and activates the mains frequency boost circuit when the signal indicates that the average or peak value of the voltage of the mains input is less than a certain threshold. In particular, the detection circuit is implemented by a voltage divider circuit R2 and R3, and diode D2 and capacitor Cl for peak detection to obtain the peak value (or average value) of the voltage of the mains input. The negative input of operational amplifier U2 is connected to the peak value of the voltage of the mains input, and the positive input of operational amplifier U2 is connected to a reference value which determines whether the mains frequency boost circuit is activated or not. When the detected peak value of the voltage of the mains input is lower than the reference value, it is considered that the mains input is too low, and the output of operational amplifier U2 is high to turn on switch Q2 to activate the mains frequency boost circuit. On the contrary, it is considered that the mains input is appropriate, and the output of operational amplifier U2 is low to deactivate the mains frequency boost circuit. A typical reference value corresponds to an average value of the mains input of 225 V, i.e. the mains frequency boost circuit is deactivated when the average value of the mains input is greater than 225 V, and activated when the average value of the mains input is less than 225 V.

[0057] The mains frequency boosting circuit can have many implementation manners, in a preferred embodiment of the utility model, the mains frequency boosting circuit is implemented by a half-wave charge pump boosting circuit, the capacitor includes a charge pump capacitor El_cap2. The driving device includes a rectifier bridge implemented by diodes D1, D2, D3 and D4, connected between the input interface and the linear driving circuit. The charge pump capacitor El_cap2 is connected between the input interface and the negative input of the rectifier bridge. The charge pump capacitor El_cap2 is used to be charged when the mains input is in a first polarity, and is used to be boosted when the mains input is in a second polarity. Specifically, when the polarity of the mains input AC is positive up and negative down, the charge pump capacitor El_cap2 is charged to be positive up and negative down. When the polarity of the mains AC becomes negative up and positive down, the charge pump capacitor El_cap2 and the mains AC become a series connection, the voltage is boosted by superposition and is provided to the subsequent linear driving circuit through the diode D1 of the rectifier bridge, and the subsequent smoothing capacitor El_cap1 is also charged. Wherein, since the voltage of the smoothing capacitor El_cap1 will be higher than the voltage on the charge pump capacitor El_cap2, the diode D2 is naturally cut off; and since the voltage of the charge pump capacitor El_cap2 exists, D4 is also naturally cut off.

[0058] The switch Q2 is connected in series with the charge pump capacitor El_cap2. When the switch Q2 is turned on, the half-wave charge pump boosting circuit is activated; when the switch Q2 is turned off, the half-wave charge pump boosting circuit is deactivated.

[0059] Fig. 5 shows the internal working voltage of the driving device of Fig. 4 when the mains input has different root mean square values. Among them, the bus voltage corresponding to 250Vac and 230Vac is not boosted; the bus voltage corresponding to 210Vac is boosted. In this case, the LED voltage VLED is set to about 300V, which can make the difference between the bus voltage and the LED voltage in various cases of input mains maintain a small range, and reduce the power consumption of the driving device. In a specific implementation, the efficiency of the driving device can reach about 94% in the case of various possible mains inputs, which is much better than the efficiency of about 80% in Fig. 1.

[0060] For the linear driving circuit, it includes a MOSFET Q1 working in a linear mode, a current detection resistor R1 and an operational amplifier U1 for negative feedback control, which works in a similar way to the linear driving circuit in the prior art of Fig. 1, and the description is not repeated here.

[0061] The above describes the embodiment of the utility model based on the charge pump mains frequency boosting circuit, it can be understood that the utility model can also be implemented by other forms of mains frequency boosting circuit.

[0062] Figure 7 shows a further improved embodiment based on the embodiment of Figure 4. Elements shown with the same reference numerals as in Figure 4 have substantially the same function as in Figure 4. The added parts include a voltage detection circuit comprising R3, R4, a comparator, an adder, and a digital-to-analog converter DAC. The functions of these added parts will be explained in detail below.

[0063] The further improved embodiment mainly provides a variable reference signal Ref2. The voltage detection circuit comprising R3, R4, the comparator, the adder, and the digital-to-analog converter DAC form a first reference signal generating circuit which generates the variable first reference signal Ref2 based on the voltage drop across the linear driver circuit Ql. This feedback is in the form of negative feedback so that the voltage drop across the linear driver circuit Ql is lower, thus improving the efficiency of the linear driver circuit Ql.

[0064] More specifically, when the voltage drop across the linear driver circuit Ql detected by R3 and R4 is greater than a second threshold value Vt2 as compared by the comparator, the first reference signal Ref2 generated by the comparator, the adder, and the DAC (where the adder and the DAC mainly function to control the increase or decrease of the control signal and the digital-to-analog conversion based on the result of the comparator) is lower than the first reference signal Ref2 when the voltage drop across the linear driver circuit Ql is less than the second threshold value Vt2. The principle behind this is that when the voltage drop across the linear driver circuit Ql is greater than the second threshold value Vt2, the power consumption of the linear driver circuit Ql is higher, and thus a lower first reference signal Ref2 can be provided so that the mains frequency voltage regulating circuit is deactivated at a lower voltage condition to reduce the voltage output to the linear driver circuit Ql and thus reduce its power consumption.

[0065] In the above embodiment, the mains frequency voltage regulating circuit is a mains frequency voltage boosting circuit. In an alternative embodiment, the mains frequency voltage regulating circuit can also be implemented as a mains frequency voltage reducing circuit. Correspondingly, the detection circuit detects a signal indicative of the average or peak value of the voltage of the mains input, and when the signal indicates that the average or peak value of the voltage of the mains input is greater than a certain threshold value, the mains frequency voltage reducing circuit is activated so that the voltage from the mains input to the linear driver circuit is reduced to an appropriate extent; and when the signal indicates that the average or peak value of the voltage of the mains input is less than the certain threshold value, the mains input is naturally suitable for the linear driver circuit, and the mains frequency voltage reducing circuit is deactivated.

[0066] Figure 6 shows an embodiment of the mains frequency voltage reduction circuit implemented using a mains frequency capacitor voltage reduction circuit. For the linear driver circuit, it comprises a MOSFET Ql operating in linear mode, a current sense resistor Rl and an operational amplifier Ul for negative feedback control. This part of the circuit operates in a similar manner as the linear driver circuit in the prior art, for example, Figure 1. Typically, a smoothing capacitor El_capl is connected in parallel across the linear driver circuit and the semiconductor light emitting device.

[0067] For the mains frequency capacitor voltage reduction circuit, it comprises voltage reduction capacitors Cl and C2. These two voltage reduction capacitors Cl and C2 are connected in series between the input interface and the linear driver circuit. In the embodiment shown in Figure 6, the voltage reduction capacitors Cl and C2 are located between the input interface and the rectifier bridge DBl. The principle and operation of the capacitor voltage reduction circuit is well known to those skilled in the art and will not be described in detail.

[0068] To activate and deactivate the mains frequency capacitor voltage reduction circuit, a bypass technique is used. That is, a bypass branch is connected in parallel with the mains frequency capacitor voltage reduction circuit as a whole. When the bypass branch is closed, the mains frequency capacitor voltage reduction circuit is bypassed, i.e. deactivated. When the bypass branch is opened, the mains frequency capacitor voltage reduction circuit is activated naturally. In the embodiment shown in Figure 6, the bypass branch is formed by a rectifier bridge DB2 connected between the input interface and the linear driver circuit. The rectifier bridge DB2 bypasses the voltage reduction capacitors Cl and C2 and the rectifier bridge DBl. The bypass branch is controlled by a bypass switch Q3 connected between the output of the rectifier bridge DB2 and the linear driver circuit. Also, a control switch Q2 is included between the rectifier bridge DBl and the linear driver circuit.

[0069] As shown in Figure 6, the control circuit functional block controls the switches Q3 and Q2 to select the activation or deactivation of the mains frequency capacitor voltage reduction circuit. Specifically, the control circuit controls the switches Q3 and Q2 with complementary control logic. When the switch Q3 is closed and the switch Q2 is opened, the bypass branch is closed and the mains frequency capacitor voltage reduction circuit is deactivated. When the switch Q2 is closed and the switch Q3 is opened, the bypass branch is opened and the mains frequency capacitor voltage reduction circuit is activated. This implementation has the advantage that the bypass switch Q3 and the control switch Q2 are both located on the DC side after the rectifier bridge, making the driving control easier. Alternatively, an AC switch, such as a Triac, can be connected in parallel across the voltage reduction capacitors Cl and C2 to activate or deactivate the voltage reduction capacitors Cl and C2. However, this has the disadvantage that the driving control of the Triac will be more complex.

[0070] In the embodiment of Fig. 3, the detection circuit is directly connected to the input interface to detect the average or peak value of the mains input. Alternatively, the detection circuit of the embodiment of Fig. 6 is connected to the drain (and gate or ground) of the linear switch Ql to detect the voltage across the linear switch / linear driver circuit. When the voltage is too high, meaning the average / peak or instantaneous value of the mains input is too high, the control circuit should activate the mains frequency capacitor bucking circuit; conversely, when the voltage is appropriate or too low, meaning the average / peak or instantaneous value of the mains input is appropriate or too low, the control circuit should deactivate the mains frequency capacitor bucking circuit. Among them, for switching according to the average / peak of the mains input, the activation or deactivation of the mains frequency capacitor bucking circuit is basically static, that is, it will last for many cycles of the mains input; and for switching according to the instantaneous value of the mains input, the activation or deactivation of the mains frequency capacitor bucking circuit should be dynamic, that is, in a mains cycle, the activation or deactivation of the mains frequency capacitor bucking circuit will appear alternately.

[0071] It is worth noting that the detection circuit in Fig. 6 can be interchanged with the detection circuit in Fig. 3, i.e. Fig. 6 is changed to the direct open-loop detection of the mains input in Fig. 3, and Fig. 3 is changed to the closed-loop detection of the voltage across the linear switch in Fig. 6.

[0072] The newly added principle / similar circuit in the embodiment of Fig. 7 can also be applied to Fig. 6 using a mains frequency bucking converter. The first reference signal when the voltage drop on the linear driver circuit is greater than the second threshold is lower than the first reference signal when the voltage drop on the linear driver circuit is less than the second threshold. The principle of doing so is that when the voltage drop on the linear driver circuit is greater than the second threshold, the power consumption on the linear driver circuit is large, so a smaller first reference signal can be provided, so that the mains frequency bucking circuit is activated at a lower voltage condition to reduce the voltage output to the linear driver circuit and thus reduce its power consumption.

[0073] In a more specific implementation, the applicant finds that if the driving device starts from a power-off state and / or the voltage on the smoothing capacitor El_cap1 is lower than a certain threshold, the capacitor voltage reduction circuit will bear a relatively large voltage, and the voltage borne by the capacitor voltage reduction circuit will be particularly large when the mains voltage is at the peak value at the time of starting, and can even exceed the voltage reduction capability of the capacitor voltage reduction circuit. Therefore, in order to protect the capacitor voltage reduction circuit, the present implementation proposes that at the time of starting, the voltage reduction circuit is deactivated regardless of whether the input voltage indicated by the signal detected by the detection circuit is large or small, so that the voltage reduction circuit can be prevented from being damaged; after the driving device starts to work from the power-off state and the voltage on the smoothing capacitor is higher than the certain threshold, the mains frequency voltage regulation circuit is selectively activated or deactivated according to the signal detected by the detection circuit, so that the power consumption of the driving device in the steady state can be reduced.

[0074] The detection circuit and the control circuit in the above two embodiments can be integrated in an integrated circuit IC, and the integrated circuit can also integrate corresponding control switches and the like.

[0075] It should be noted that when an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0076] In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implying a specific number of the technical features indicated. Therefore, the features defined as "first", "second", etc. can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0077] Finally, it should be noted that the terms "include", "contain" or any other variant are intended to cover non-exclusive inclusion, so that the process, method, article or terminal device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or terminal device, and does not exclude the presence of other identical elements in the process, method, article or terminal device including the elements.

[0078] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. Driving device for driving a semiconductor light emitting device (LED), comprising - an input interface for connection to an AC input; - an output interface for connection in series with a linear driving circuit (Ql) and for connection to the semiconductor light emitting device (LED) through the linear driving circuit (Ql); characterized in that it further comprises - an AC frequency voltage regulation circuit coupled between the input interface and the linear driving circuit for power conversion at AC frequency to vary the voltage amplitude of the AC input provided to the linear driving circuit, the AC frequency voltage regulation circuit comprising a capacitor or an inductor charged and discharged at AC frequency; - a detection circuit for detecting a signal related to the voltage of the AC input; - a control circuit for selectively activating or deactivating the AC frequency voltage regulation circuit depending on the signal detected by the detection circuit.

2. The drive apparatus according to claim 1, characterized by the AC frequency voltage regulation circuit comprises an AC frequency voltage boost circuit, the control circuit is configured to: deactivate the AC frequency voltage boost circuit when the signal indicates that the voltage of the AC input is greater than a certain threshold; and activate the AC frequency voltage boost circuit when the signal indicates that the voltage of the AC input is less than the certain threshold.

3. The drive apparatus according to claim 1, characterized by the detection circuit is configured to detect a signal related to the average or peak value of the voltage of the AC input, the AC frequency voltage boost circuit comprises a half-wave or full-wave charge pump boost circuit, the capacitor comprising a charge pump capacitor (El_cap2).

4. The drive apparatus according to claim 3, characterized by the driving device comprises - a rectifier bridge (Dl, D2, D3, D4) connected between the input interface and the linear driving circuit; and - a smoothing capacitor (El_capl) connected in parallel to the linear driving circuit and to the output interface; the charge pump capacitor (El_cap2) is connected between the input interface and the negative input of the rectifier bridge, the charge pump capacitor (El_cap2) being configured to be charged when the AC input is at a first polarity and to be boosted when the AC input is at a second polarity superimposed to the AC input.

5. The driving device according to claim 4, the control circuit comprising a switch (Q2) connected in series with the charge pump capacitor (El_cap2) between the input interface and the negative input of the rectifier bridge, the control circuit being configured to open the switch (Q2) to deactivate the AC frequency voltage boost circuit and to close the switch (Q2) to activate the AC frequency voltage boost circuit. the AC frequency voltage regulation circuit comprises an AC frequency voltage step-down circuit, 6. The drive apparatus according to claim 1, characterized by the control circuit is configured to: activate the AC frequency voltage step-down circuit when the signal indicates that the average or peak value of the voltage of the AC input is greater than a certain threshold; and deactivate the AC frequency voltage step-down circuit when the signal indicates that the average or peak value of the voltage of the AC input is less than the certain threshold. the AC frequency voltage step-down circuit comprises a capacitor step-down circuit comprising 7. The drive apparatus according to claim 6, characterized by a step-down capacitor (Cl, C2) connected in series between the input interface and the linear driving circuit. the control circuit comprises 8. Drive arrangement according to claim 6 or 7, characterized in that ​ - a bypass branch, in parallel with said capacitive voltage reduction circuit; said control circuit being configured to close said bypass branch to deactivate said capacitive voltage reduction circuit, and to open said bypass branch to activate said capacitive voltage reduction circuit.

9. The drive apparatus according to claim 7, characterized by Further comprising: a smoothing capacitor (El_capl), in parallel with said linear drive circuit and said output interface; said control circuit being configured to: deactivate said voltage reduction circuit independently of said signal detected by said detection circuit, when said drive device is just starting from a power-off state and / or when the voltage on said smoothing capacitor is below a certain threshold value; selectively activate or deactivate said mains frequency voltage regulation circuit according to said signal detected by said detection circuit, after said drive device has reached a steady state from a power-off state and / or after the voltage on said smoothing capacitor is above said certain threshold value.

10. The drive apparatus according to any one of claims 2 or 6, characterized by, said detection circuit comprising a first voltage detection circuit (R2, R3) connected to said input interface and directly detecting a signal indicative of said mains input, to obtain a first signal related to the average or peak or instantaneous value of the voltage thereof.

11. The drive apparatus according to claim 10, characterized by said first voltage detection circuit comprising a peak detection circuit, and / or said control circuit comprising a comparator configured to receive a first reference signal (Ref2) and said first signal, said first reference signal (Ref2) corresponding to a threshold value of the average or peak value of the voltage of said mains input.

12. The drive apparatus according to claim 10, characterized by Further comprising a first reference signal generation circuit configured to: generate a fixed said first reference signal (Ref2); or generate a variable said first reference signal (Ref2).

13. The drive apparatus according to claim 10, characterized by said first reference signal generation circuit being configured to generate a variable said first reference signal (Ref2) according to the voltage drop across said linear drive circuit (Ql) to implement a negative feedback control, wherein when said mains frequency voltage regulation circuit comprises a mains frequency voltage step-up circuit, said first reference signal (Ref2) when the voltage drop across said linear drive circuit (Ql) is greater than a second threshold value is lower than said first reference signal (Ref2) when the voltage drop across said linear drive circuit (Ql) is lower than said second threshold value; when said mains frequency voltage regulation circuit comprises a mains frequency voltage step-down circuit, said first reference signal (Ref2) when the voltage drop across said linear drive circuit (Ql) is greater than a second threshold value is lower than said first reference signal (Ref2) when the voltage drop across said linear drive circuit (Ql) is lower than said second threshold value.

14. The drive apparatus according to claim 1, characterized by said detection circuit comprising a second voltage detection circuit connected to said linear drive circuit, configured to detect the voltage across said linear drive circuit as a second signal, said second signal being indirectly indicative of the average or peak or instantaneous value of the voltage of said mains input.

15. An integrated circuit controller comprising a drive device according to any one of claims 1 to 14, said integrated circuit controller integrating said detection circuit and said control circuit.

16. An integrated circuit for driving a semiconductor light emitting device, comprising an integrated circuit controller according to claim 15, and The linear driving circuit (Q1) is coupled to the input interface for converting the mains input from the input interface into a driving current.

17. A lighting apparatus based on a semiconductor light emitting device, comprising a semiconductor light emitting device, and the integrated circuit for driving a semiconductor light emitting device as claimed in claim 16, wherein the semiconductor light emitting device comprises a light emitting diode (LED) or a laser diode.

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