Voltage regulation circuit, control method and driving device

Abstract

The present invention discloses a voltage regulating circuit (10, 10a), a control method (400), and a driving device (3). The voltage regulating circuit (10, 10a) comprises: a first input port (X1-a) and a second input port (X1-b), the first input port and the second input port being configured to receive an input voltage; a first output port (X2-a) and a second output port (X2-b), the first output port and the second output port being configured to output an output voltage, the first input port (X1-a) being connected to the first output port (X2-a); an output circuit (100), the output circuit being configured to be connected between the first output port (X2-a) and the second output port (X2-b); and a voltage regulator (200), the voltage regulator being configured to be connected between the first output port (X2-a) and the second output port (X2-b), thereby adjusting the voltage according to a reference voltage (U1 ) sets the output voltage to a predetermined value; a first transistor (Q3), the first transistor being configured to be connected between the second output port (X2-b) and the second input port (X1-b), the control terminal of the first transistor (Q3) being coupled to the first output port (X2-a); a voltage detector (300, 300a), the voltage detector being configured to be connected to the first output port (X2-a) and the voltage regulator (200), the voltage detector (300) turning off the first transistor (Q3) when the output voltage is higher than the predetermined value; and a second transistor (Q2), the second transistor being configured to be coupled between the control terminal of the first transistor (Q3) and the second input port (X1-b), the control terminal of the second transistor (Q2) receiving a dimming signal.

Description

Technical Field

[0001] Embodiments of the present disclosure relate generally to the field of circuits, and more particularly to voltage regulation circuits, control methods, and driving devices. Background Art

[0002] This section introduces aspects that may be helpful in better understanding the present disclosure. Therefore, the statements in this section should be read in this light and should not be understood as admissions of what is or is not in the prior art.

[0003] In the field of lighting technology, it is usually necessary to configure a driving current for driving a lighting device, such as an LED (light emitting diode).

[0004] The lighting device is driven by a driver that outputs a direct current to the lighting device. Most low-cost drivers have a high ripple factor, such as ±30% or even higher. This high ripple factor can cause the lighting device to flicker. A transistor can be used as a voltage regulator to reduce this ripple.

[0005] In many applications of constant voltage (CV) circuits, pulse width modulation (PWM) dimming is required. A transistor acts as a voltage switch to turn the output voltage on or off. Summary of the Invention

[0006] The inventors of the present disclosure have found that a circuit with ripple suppression and PWM dimming functions requires two transistors, one for ripple suppression and the other for output voltage switching for PWM dimming, which results in higher costs.

[0007] Generally speaking, embodiments of the present disclosure provide voltage regulation circuits, control methods, and drive devices. In one embodiment, a single transistor is used for both ripple suppression and output voltage switching for PWM dimming. This results in lower cost and requires less space in the voltage regulation circuit.

[0008] In a first aspect, a voltage regulation circuit is provided, the voltage regulation circuit comprising:

[0009] a first input port X1 - a and a second input port X1 - b , the first input port and the second input port being configured to receive an input voltage;

[0010] a first output port X2 - a and a second output port X2 - b , wherein the first output port and the second output port are configured to output an output voltage, and the first input port is connected to the first output port;

[0011] an output circuit 100 configured to be connected between a first output port and a second output port;

[0012] a voltage regulator 200 configured to be connected between the first output port and the second output port so as to set the output voltage to a predetermined value according to the reference voltage U1;

[0013] a first transistor Q3, the first transistor being configured to be connected between the second output port and the second input port, wherein a control terminal of the first transistor Q3 is coupled to the first output port;

[0014] a voltage detector 300, 300a, configured to be connected to the first output port and the voltage regulator 200, and to turn off the first transistor Q3 when the output voltage is higher than a predetermined value; and

[0015] The second transistor Q2 is configured to be coupled between the control terminal of the first transistor Q3 and the second input port, and the control terminal of the second transistor Q2 receives a dimming signal.

[0016] In another embodiment, the voltage regulator 200 includes:

[0017] a first resistor R3 and a second resistor R7 configured to be connected in series between the first output port and the second output port; and

[0018] A reference voltage generator, the anode of which is connected to the second output port, the cathode of which is connected to the voltage detector 300, the reference terminal of which is connected to the connection node of the first resistor R3 and the second resistor R7, and the cathode of which outputs the reference voltage.

[0019] In another embodiment, the voltage regulator 200 further includes:

[0020] A first capacitor C2 and a third resistor R11 are configured to be connected in series between a cathode of the reference voltage generator and a reference terminal.

[0021] In another embodiment, the fourth resistor R10 and the fifth resistor R12 are connected in series between the first output port and the control port of the first transistor Q3.

[0022] The sixth resistor R9 is connected between the control port and the second input port of the first transistor Q3 .

[0023] In another embodiment, the voltage detector 300 includes:

[0024] a seventh resistor R1, an eighth resistor R2, and a diode D6, the seventh resistor, the eighth resistor, and the diode being configured to be connected in series between the first input port and the voltage regulator 200; and

[0025] An optocoupler U3, an anode of an input LED in the optocoupler U3 is connected to a node connecting the seventh resistor R1 and the eighth resistor R2, a cathode of the input LED in the optocoupler U3 is connected to a node connecting the eighth resistor R2 and the diode D6, a collector of an output transistor in the optocoupler U3 is connected to a collector of the second transistor Q2, and an emitter of the output transistor in the optocoupler U3 is connected to the second input port.

[0026] In another embodiment, the voltage detector 300a includes:

[0027] a seventh resistor R1, an eighth resistor R2, and a diode D6, the seventh resistor, the eighth resistor, and the diode being configured to be connected in series between the first input port and the voltage regulator 200; and

[0028] The third transistor Q1 has an emitter coupled to the first input port via a ninth resistor R14 , a collector coupled to the base of the second transistor Q2 , and a base connected to the eighth resistor R2 .

[0029] In a second aspect, a control method of a ripple suppression circuit is provided, the control method comprising: when the voltage of the dimming signal is higher than a threshold or the dimming signal is not supplied to the second transistor Q2, the dimming signal is higher and the first transistor is turned off.

[0030] In a third aspect, a driving device is provided. The driving device includes a driving circuit and the voltage regulator circuit according to the first aspect of the present disclosure, wherein the input voltage is provided by the driving circuit.

[0031] According to various embodiments of the present disclosure, one transistor is used for both ripple suppression and output voltage switching for PWM dimming, thereby achieving lower cost and requiring less space in the voltage regulation circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and other aspects, features and benefits of various embodiments of the present disclosure will become more apparent from the following detailed description, which refers to the accompanying drawings, by way of example, in which like reference numerals or letters are used to represent similar or equivalent elements. The accompanying drawings are shown to facilitate a better understanding of the embodiments of the present disclosure and are not necessarily drawn to scale, wherein:

[0033] Figure 1is a diagram of a voltage regulation circuit according to an embodiment of the present disclosure;

[0034] Figure 2 is a diagram of a voltage regulating circuit according to another embodiment of the present disclosure;

[0035] Figure 3 is a diagram of the driving device;

[0036] Figure 4 A flow chart of a control method 400 of a voltage regulation circuit is shown. DETAILED DESCRIPTION

[0037] The present disclosure will now be discussed with reference to several exemplary embodiments. It should be understood that the purpose of discussing these embodiments is only to enable those skilled in the art to better understand the present disclosure and thus implement the present disclosure, rather than to propose any limitation on the scope of the present disclosure.

[0038] As used herein, the terms "first" and "second" refer to different elements. Unless the context clearly indicates otherwise, the singular forms "a" and "an" are intended to also include the plural forms. As used herein, the terms "include", "comprise", "have" and / or "contain" specify the presence of the features, elements and / or components, etc., but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. The term "based on" should be understood as "based at least in part on". The terms "one embodiment" and "embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". Other explicit and implicit definitions may be included below.

[0039] First aspect of the implementation plan

[0040] In a first embodiment, a voltage regulating circuit is provided.

[0041] Figure 1 is a diagram of a voltage regulation circuit according to an embodiment of the present disclosure. Figure 1 As shown, the voltage regulating circuit 10 includes a first input port X1-a, a second input port X1-b, a first output port X2-a, a second output port X2-b, an output circuit 100, a voltage regulator 200, a first transistor Q3, a voltage detector 300 and a second transistor Q2.

[0042] In an embodiment, the first input port X1-a and the second input port X1-b are configured to receive an input voltage. The input voltage may be a DC / voltage with ripple. The input voltage may be provided by a driver circuit, for example, a single-stage constant voltage (CV) circuit.

[0043] The first output port X2 - a and the second output port X2 - b are configured to output an output voltage. The first input port X1 - a is connected to the first output port X2 - a , so the first input port X1 - a and the first output port X2 - a may have the same voltage.

[0044] The output circuit 100 is configured to be connected between a first output port X2-a and a second output port X2-b. The output circuit 100 includes a resistor R4, a capacitor C5, and a diode D5. The resistor R4, capacitor C5, and diode D5 are connected in parallel between the first output port X2-a and the second output port X2-b. The anode of the diode D5 is connected to the second output port X2-b, and the cathode of the diode D5 is connected to the first output port X2-a.

[0045] The voltage regulator 200 is configured to be connected between the first output port X2 - a and the second output port X2 - b so as to set the output voltage to a predetermined value according to the reference voltage U1 .

[0046] For example, Figure 1 As shown, the voltage regulator 200 includes a first resistor R3 , a second resistor R7 and a reference voltage generator 201 .

[0047] The first resistor R3 and the second resistor R7 are configured to be connected in series between the first output port X2 - a and the second output port X2 - b.

[0048] Reference voltage generator 201 generates a reference voltage U1. The anode of reference voltage generator 201 is connected to second output port X2-b, the cathode of reference voltage generator 201 is connected to voltage detector 300, and the reference terminal of voltage generator 201 is connected to the connection node A between first resistor R3 and second resistor R7. Reference voltage U1 is output from the cathode of reference voltage generator 201. By adjusting the resistances of R3 and R7, reference voltage U1 can be varied. The output voltages output from first output port X2-a and second output port X2-b are set to predetermined values, for example, 24V. As reference voltage U1 changes, the predetermined value changes.

[0049] like Figure 1 As shown, the voltage regulator 200 further includes a first capacitor C2 and a third resistor R11. The capacitor C2 and the resistor R11 are configured to be connected in series between the cathode and the reference terminal of the reference voltage generator 201. The capacitor C2 is used to filter out ripples in the output voltage.

[0050] like Figure 1As shown, the first transistor Q3 is configured to be connected between the second output port X2-b and the second input port X1-b. The control terminal of the first transistor Q3 is coupled to the first output port X2-a. For example, resistors R10 and R12 are connected in series between the first output port X2-a and the control port of the first transistor Q3. Resistor R9 is connected between the control port of the first transistor Q3 and the second input port X1-b.

[0051] like Figure 1 As shown, the first transistor Q3 is a MOS FET (metal oxide semiconductor field effect transistor). The control terminal of the first transistor Q3 is a gate. The drain of the first transistor Q3 is connected to the second output port X2-b. The source of the first transistor Q3 is connected to the second input port X1-b. The embodiment is not limited thereto; the first transistor Q3 can be another type, for example, a bipolar transistor such as an NPN bipolar transistor.

[0052] The voltage detector 300 is configured to be connected to the first output port X2-a and the voltage regulator 200. When the output voltage is detected to be higher than a predetermined value, the voltage detector 300 pulls down the drive voltage of the first transistor Q3. The pull-down drive voltage of Q3 increases the Ron (on-resistance) of Q3, and then the voltage drop across the first transistor Q3 increases, thereby suppressing the ripple of the output voltage. Therefore, the first transistor Q3 can function as a ripple suppressor.

[0053] The second transistor Q2 is configured to be coupled between the control terminal of the first transistor Q3 and the second input port X1-b. The control terminal of the second transistor Q2 receives a dimming signal. The dimming signal is provided by an external PWM dimming signal generator V4. A resistor R6 is connected between the control terminal of the second transistor Q2 and the external PWM dimming signal generator V4. A resistor R8 is connected between the control terminal of the second transistor Q2 and the second input port X1-b.

[0054] like Figure 1 As shown, the second transistor Q2 is an NPN bipolar transistor, and the control terminal of the second transistor Q2 is the base of the NPN bipolar transistor. The embodiment is not limited thereto; the second transistor Q2 can be of other types, such as a MOSFET.

[0055] When the dimming signal is low or the external PWM dimming signal generator V4 is not connected to the control terminal of transistor Q2, the voltage drop across R8 cannot turn on the second transistor Q2, does not pull down the drive voltage of the first transistor Q3, and the first transistor Q3 operates in the linear region for ripple suppression. The output voltage is output from the first output port X2-a and the second output port X2-b. When the dimming signal is high, the voltage drop across R8 can turn on the second transistor Q2, pulling down the drive voltage of the first transistor Q3, and turn off the first transistor Q3, so that no output voltage is output from the first output port X2-a and the second output port X2-b. Therefore, the first transistor Q3 can be used as an output voltage switch for PWM dimming.

[0056] According to the embodiment of the present disclosure, the first transistor Q3 serves two purposes: one is ripple suppression, and the other is output voltage switching for PWM dimming. Therefore, one transistor can be omitted, resulting in lower cost and requiring less space in the voltage regulation circuit.

[0057] like Figure 1 As shown, in at least one embodiment, the voltage detector 300 includes a resistor R1 , a resistor R2 , a diode D6 , and an optocoupler U3 .

[0058] Resistor R1, resistor R2, and diode D6 are configured to be connected in series between the first input port X1-a and the voltage regulator 200. For example, the anode of diode D6 is connected to resistor R2, and the cathode of diode D6 is connected to the cathode of reference voltage generator 201.

[0059] Optocoupler U3 includes an input LED and an output transistor. The anode of the input LED in optocoupler U3 is connected to the node connecting resistors R1 and R2, and the cathode of the input LED is connected to the node connecting resistor R2 and diode D6. The collector of the output transistor in optocoupler U3 is connected to the collector of the second transistor Q2, and the emitter of the output transistor in optocoupler U3 is connected to the second input port X1-b.

[0060] like Figure 1 As shown, when the output voltage is higher than a predetermined value as the ripple peak, the voltage at the cathode of the reference voltage generator 201 pulls the input LED in U3 into conduction, and the output transistor pulls down the drive voltage of Q3, and then the voltage drop across Q3 increases, so there is an overvoltage across Q3 to maintain the output voltage to the predetermined value and cut the ripple peak.

[0061] Figure 2 is a diagram of a voltage regulating circuit according to another embodiment of the present disclosure. Figure 2 The voltage detector 300a in Figure 1 The voltage detector 300 in FIG. 3 is different. Figure 1 and Figure 2 Descriptions of identical components with the same label.

[0062] like Figure 2 As shown, the voltage regulating circuit 10a includes a voltage detector 300a, which includes a resistor R1, a resistor R2, a diode D6, and a third transistor Q1.

[0063] like Figure 2 As shown, resistor R1, resistor R2 and diode D6 are configured to be connected in series between the first input port X1-a and the voltage regulator 200. For example, the anode of diode D6 is connected to resistor R2, and the cathode of diode D6 is connected to the cathode of reference voltage generator 201.

[0064] The emitter of the third transistor Q1 is coupled to the first input port X1 - a via the resistor R14 , the collector of the third transistor Q1 is coupled to the base of the second transistor Q2 via the resistor R13 , and the base of the third transistor Q1 is connected to the connection node between the resistors R1 and R2 .

[0065] The third transistor Q1 is a PNP bipolar transistor. The embodiment is not limited thereto; the third transistor Q3 may be of other types, such as a MOS FET.

[0066] like Figure 2 As shown in FIG, when the output voltage exceeds a predetermined value, which is a ripple peak value, the voltage at the cathode of the reference voltage generator 201 pulls the third transistor Q1 into conduction and pulls up the second transistor Q2 into conduction. Then, the drive voltage of Q3 is pulled down, and the voltage drop across Q3 increases. Therefore, an overvoltage exists across Q3, maintaining the output voltage at the predetermined value and reducing the ripple peak value.

[0067] In addition, if Figure 1 and Figure 2 As shown, the voltage regulating circuits 10 and 10a may further include a resistor R5 and a capacitor C1.

[0068] Figure 3 is a diagram of the drive device. Figure 3 As shown, the driving device 3 includes a voltage regulating circuit 10 and a driving circuit 30 .

[0069] The driving device 3 further includes a rectifier 40, which includes a diode D1, a diode D, a diode D3, and a diode D1. The rectifier 40 rectifies the voltages provided by the power supplies V1 and V2. V1 provides a DC voltage, and V2 provides a sinusoidal signal superimposed on the DC voltage.

[0070] The drive circuit 30 is a constant voltage circuit, for example, a single-stage constant voltage circuit, which supplies an input voltage to the voltage regulating circuit 10 .

[0071] In another embodiment, Figure 3 The drive device 3 in Figure 2 The voltage detector 300a in is replaced.

[0072] The drive circuit 30 may be formed by a flyback converter, a resonant half-bridge converter, or an LLC converter including a transformer. Instead of a transformer, a portion of a switching converter may be derived from an inductor, such as a buck converter or a boost converter forming the drive circuit. The timing of the drive circuit, particularly the transformer, by at least one controllable switch clocked at a high frequency may depend on a control signal input to a control input of the drive circuit. For example, the frequency and / or duty cycle of the controllable switch of the drive circuit may be adjusted based on the control signal input to the input of the drive circuit.

[0073] The driving circuit can generate a driving current or a driving voltage for the lighting device and output the driving current or the driving voltage for the lighting device at the first input port X1-a and the second input port X1-b, so as to output the input voltage to the voltage regulating circuit 10 (or 10a).

[0074] Second aspect of the implementation plan

[0075] A method for controlling a voltage regulating circuit. In one embodiment, a voltage regulating circuit according to the first aspect of the embodiment is provided. The same contents as those in the first aspect of the embodiment are omitted.

[0076] Figure 4 A flow chart of a control method 400 of a voltage regulation circuit is shown.

[0077] like Figure 4 As shown, the method 400 includes:

[0078] Box 401: When the output voltage is higher than a predetermined value, the voltage detector (300) turns off the first transistor; or when the voltage of the dimming signal is higher than a threshold or the dimming signal is not supplied to the second transistor (Q2), the dimming signal is higher and the first transistor is turned off.

[0079] As can be seen from the above embodiment, the first transistor Q3 serves two purposes: one is ripple suppression, and the other is output voltage switching for PWM dimming. Therefore, one transistor can be omitted, resulting in lower cost and requiring less space in the voltage regulation circuit.

[0080] The third aspect of the implementation plan

[0081] In one embodiment, a driving device is provided, comprising a driving circuit and the voltage regulating circuit according to the first aspect of the embodiment.

[0082] In an embodiment, the voltage regulating circuit receives an input voltage provided by the driving circuit and outputs a signal with a low ripple coefficient. The signal with a low ripple coefficient can be provided to the lighting device, so that the flicker of the lighting device can be reduced.

[0083] In addition, although the operations are shown in a specific order, this situation should not be understood as needing to perform such operations in the specific order shown or in a sequential order or needing to perform all the operations shown to achieve the desired result. In some cases, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these specific implementation details should not be understood as limiting the scope of the present disclosure, but should be understood as descriptions of features that may be specific to a specific embodiment. Some features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in the form of any suitable subcombination.

[0084] Although the present disclosure has been described in language specific to structural features and / or methodological acts, it should be understood that the present disclosure as defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as exemplary forms of implementing the claims.

Claims

1. A voltage regulating circuit, comprising: a first input port (X1-a) and a second input port (X1-b), the first input port and the second input port being configured to receive an input voltage; a first output port (X2-a) and a second output port (X2-b), wherein the first output port and the second output port are configured to output an output voltage, and the first input port is connected to the first output port; an output circuit (100), the output circuit being configured to be connected between the first output port and the second output port; a voltage regulator (200) configured to be connected between the first output port and the second output port so as to set the output voltage to a predetermined value according to a reference voltage (U1); a first transistor (Q3) configured to be connected between the second output port and the second input port, a control terminal of the first transistor (Q3) being coupled to the first output port; a voltage detector (300, 300a), the voltage detector being configured to be connected to the first output port and the voltage regulator (200), and the voltage detector (300) turning off the first transistor (Q3) when the output voltage is higher than the predetermined value; and A second transistor (Q2) is configured to be coupled between the control terminal of the first transistor (Q3) and the second input port, and the control terminal of the second transistor (Q2) receives a dimming signal.

2. The voltage regulating circuit according to claim 1, wherein: The voltage regulator (200) comprises: a first resistor (R3) and a second resistor (R7), the first resistor and the second resistor being configured to be connected in series between the first output port and the second output port; and A reference voltage generator, wherein the anode of the reference voltage generator is connected to the second output port, the cathode of the reference voltage generator is connected to the voltage detector (300), the reference terminal of the reference voltage generator is connected to the connection node of the first resistor (R3) and the second resistor (R7), and the cathode of the reference voltage generator outputs the reference voltage.

3. The voltage regulating circuit according to claim 2, wherein: The voltage regulator (200) further comprises: A first capacitor (C2) and a third resistor (R11) are configured to be connected in series between the cathode of the reference voltage generator and the reference terminal.

4. The voltage regulating circuit according to claim 1, wherein: a fourth resistor (R10) and a fifth resistor (R12) connected in series between the first output port and the control port of the first transistor (Q3), A sixth resistor (R9) is connected between the control port of the first transistor (Q3) and the second input port.

5. The voltage regulating circuit according to claim 1, wherein: The voltage detector (300) comprises: a seventh resistor (R1), an eighth resistor (R2), and a diode (D6), the seventh resistor, the eighth resistor, and the diode being configured to be connected in series between the first input port and the voltage regulator (200); and An optocoupler (U3), an anode of an input LED in the optocoupler (U3) is connected to a node connecting the seventh resistor (R1) and the eighth resistor (R2), a cathode of the input LED in the optocoupler (U3) is connected to a node connecting the eighth resistor (R2) and the diode (D6), a collector of an output transistor in the optocoupler (U3) is connected to a collector of the second transistor (Q2), and an emitter of the output transistor in the optocoupler (U3) is connected to the second input port.

6. The voltage regulating circuit according to claim 1, wherein: The voltage detector (300a) comprises: a seventh resistor (R1), an eighth resistor (R2), and a diode (D6), the seventh resistor, the eighth resistor, and the diode being configured to be connected in series between the first input port and the voltage regulator (200); and a third transistor (Q1), the emitter of the third transistor (Q1) being coupled to the first input port via a ninth resistor (R14), the collector of the third transistor (Q1) being coupled to the base of the second transistor (Q2), and the base of the third transistor (Q1) being connected to the eighth resistor (R2).

7. A driving device, comprising a driving circuit and a voltage regulating circuit according to one of claims 1 to 6, wherein: The input voltage is provided by the driving circuit.

8. A method for controlling a voltage regulating circuit, the voltage regulating circuit comprising: a first input port (X1-a) and a second input port (X1-b), the first input port and the second input port being configured to receive an input voltage; a first output port (X2-a) and a second output port (X2-b), wherein the first output port and the second output port are configured to output an output voltage, and the first input port is connected to the first output port; an output circuit (100), the output circuit being configured to be connected between the first output port and the second output port; a voltage regulator (200) configured to be connected between the first output port and the second output port so as to set the output voltage to a predetermined value according to a reference voltage (U1); a first transistor (Q3) configured to be connected between the second output port and the second input port, a control terminal of the first transistor (Q3) being coupled to the first output port; a voltage detector (300, 300a), the voltage detector being configured to be connected to the first output port and the voltage regulator (200); and a second transistor (Q2), the second transistor being configured to be coupled between the control terminal of the first transistor (Q3) and the second output port, the control terminal of the second transistor (Q2) receiving a dimming signal, The control method includes: When the output voltage is higher than the predetermined value, the voltage detector (300) turns off the first transistor; or When the voltage of the dimming signal is higher than a threshold or the dimming signal is not supplied to the second transistor (Q2), the dimming signal is higher and the first transistor is turned off.

Images