阅读说明：本技术 反馈电压调整模块、高调光深度的去纹波电路及方法 (Feedback voltage adjusting module, high-dimming-depth ripple removing circuit and method ) 是由 刘军 吴泉清 卢圣晟 张识博 于 2018-08-29 设计创作，主要内容包括：本发明提供一种反馈电压调整模块、高调光深度的去纹波电路及方法,所述去纹波电路包括：LED负载；去纹波控制管；反馈电阻；根据LED负载的负端电压及去纹波控制管源端的反馈电压控制去纹波控制管的去纹波控制模块；根据输出电流调整反馈电压的反馈电压调整模块,在所述输出电流从第一设定电流减小至最小输出电流,并从所述最小输出电流增大至第二设定电流的过程中,抬高所述反馈电压,以提高电流检测能力。本发明的反馈电压调整模块、高调光深度的去纹波电路及方法用芯片去纹波电路提高系统效率的同时,在高调光深度条件下仍能有极好的去纹波调整能力,大大提高了去纹波电路的性能。(The invention provides a feedback voltage adjusting module, a ripple removing circuit with high dimming depth and a method, wherein the ripple removing circuit comprises: an LED load; a ripple wave removing control tube; a feedback resistor; the ripple removing control module controls the ripple removing control tube according to the voltage of the negative end of the LED load and the feedback voltage of the source end of the ripple removing control tube; the feedback voltage adjusting module adjusts feedback voltage according to output current, and raises the feedback voltage in the process that the output current is reduced from first set current to minimum output current and is increased from the minimum output current to second set current so as to improve current detection capability. The feedback voltage adjusting module, the high-dimming-depth ripple removing circuit and the method of the invention improve the system efficiency by using the chip ripple removing circuit, and simultaneously have excellent ripple removing adjusting capability under the condition of high dimming depth, thereby greatly improving the performance of the ripple removing circuit.)

1. The utility model provides a feedback voltage adjustment module for the ripple circuit that removes of high dimming depth, remove the ripple circuit including removing the ripple control tube and connect in remove the feedback resistance of ripple control tube source end, its characterized in that, feedback voltage adjustment module includes at least:

the current detection unit is connected to the source end of the ripple-free control tube and used for detecting the current flowing through the ripple-free control tube and generating a control signal according to the detected current;

and the at least one shunt unit is connected in parallel with the feedback resistor at the source end of the ripple-removing control tube and is used for adjusting the feedback voltage at the source end of the ripple-removing control tube according to the current flowing through the ripple-removing control tube.

2. The feedback voltage adjustment module of claim 1, wherein: the shunt unit comprises a switch tube, the source end and the drain end of the switch tube are respectively connected with the two ends of the feedback resistor, and the grid end of the switch tube is connected with the output end of the current detection unit.

3. The feedback voltage adjustment module of claim 2, wherein: the shunt unit further comprises a shunt resistor, the shunt resistor is connected with the switch tube in series, and the series-connected voltage resistor and the switch tube are connected with the feedback resistor in parallel.

4. A high dimming depth of the ripple removing circuit, characterized in that, the high dimming depth of the ripple removing circuit at least includes:

the positive end of the LED load is connected with the output end of the preceding stage circuit;

the drain end of the ripple removing control tube is connected with the negative end of the LED load, and the ripple of the output current is removed by adjusting the current flowing through the ripple removing control tube;

one end of the feedback resistor is connected with the source end of the ripple wave removing control tube, and the other end of the feedback resistor is grounded;

the ripple removing control module is connected with the negative end of the LED load and the source end of the ripple removing control tube, and controls the grid end of the ripple removing control tube according to the voltage of the negative end of the LED load and the feedback voltage of the source end of the ripple removing control tube;

the feedback voltage adjusting module of any one of claims 1 to 3, connected to a source terminal of the de-ripple control tube, for raising the feedback voltage during a process of decreasing the output current from a first set current to a minimum output current and increasing the output current from the minimum output current to a second set current, wherein the feedback voltage varies linearly with the output current.

5. The high dimming depth de-ripple circuit of claim 4, wherein: the ripple removal control module comprises a sampling unit, a compensation voltage generation unit and a driving unit; the sampling unit is connected to the negative end of the LED load to obtain the sampling voltage of the negative end of the LED load; the compensation voltage generating unit is connected to the output end of the sampling unit and the source end of the ripple wave removing control tube, and obtains corresponding compensation voltage according to the sampling voltage and the feedback voltage; the driving unit is connected with the output end of the compensation voltage generating unit and the source end of the ripple removing control tube, and controls the ripple removing control tube according to the compensation voltage and the feedback voltage.

6. The high dimming depth de-ripple circuit according to claim 4 or 5, wherein: the ripple wave removing control module is further connected with a compensation capacitor, and the other end of the compensation capacitor is grounded.

7. The high dimming depth de-ripple circuit of claim 4, wherein: the first set current is less than the second set current.

8. A method for removing ripples at a high dimming depth is characterized by at least comprising the following steps:

detecting output current during dimming, increasing the resistance value of a resistor for detecting the output current along with the reduction of the output current when the output current is smaller than a first set current so as to raise the feedback voltage of the source end of the ripple removing control tube, controlling the ripple removing control tube to perform constant current control through the feedback voltage and the voltage of the negative end of the LED load, and further removing ripples of the output current;

and when the output current is larger than a second set current, reducing the resistance of a resistor for detecting the output current so as to press down the feedback voltage at the source end of the ripple removing control tube, and controlling the ripple removing control tube to perform constant current control through the feedback voltage and the voltage at the negative end of the LED load so as to remove ripples of the output current.

9. The method for removing ripples of high dimming depth of claim 8, wherein: the resistance value of the resistor for detecting the output current is adjusted by adjusting the number or the resistance value of the shunt resistors connected in parallel with the feedback resistor.

10. The method for removing ripples of high dimming depth of claim 9, wherein: the shunt resistance is the on-resistance of a resistor or an MOS tube.

11. The method for removing ripples at high dimming depth according to any one of claims 8 to 10, wherein: the first set current is less than the second set current.

12. The method for removing ripples at high dimming depth according to any one of claims 8 to 10, wherein: the method for removing ripples of the high dimming depth further comprises the following steps: setting a plurality of set currents, and sequentially raising the feedback voltage in the process of reducing the output current; and sequentially pressing down the feedback voltage in the process of increasing the output current.

Technical Field

The invention relates to the field of circuit design, in particular to a feedback voltage adjusting module, a high-dimming-depth ripple removing circuit and a high-dimming-depth ripple removing method.

Background

Generally, in the application of a high Power Factor (PF), because of the limitation of an output capacitor, an output current has an alternating current component of a Power frequency, which may cause flicker in some occasions, and a ripple removing circuit is required to be added to filter the Power frequency component.

As shown in fig. 1, a conventional chip-controlled ripple removing circuit is provided, in which a resistor R1 and a capacitor C1 are connected in series and then connected in parallel to a preceding output end, a positive end of an LED string is connected to the preceding output end, a drain terminal of a transistor Q1 is connected to a negative end of the LED string, and a resistor R2 is connected between a source terminal of a transistor Q1 and ground; the VCC end of the ripple removing chip is connected with the upper polar plate of the capacitor C1, the GATE end is connected with the GATE end of the transistor Q1, the CS end is connected with the source end of the transistor Q1, the COMP end is grounded through the capacitor C2, and the GND end is grounded. Generally, in consideration of system efficiency, the detection voltage of the CS terminal is set to about 0.1-0.2V when the system is fully loaded, when the dimming depth is 10%, the detection voltage of the CS terminal is about 0.01-0.02V, and if the dimming depth is 1%, the detection voltage of the CS terminal is only about 1-2mV, which is difficult to be detected and processed by the chip, so that the normal way is to drive the ripple-removing transistor Q1 to be fully turned on, and not perform the ripple-removing process, thereby losing the ripple-removing effect.

As shown in fig. 2, the conventional MOSFET ripple removing circuit includes a resistor R3 and a capacitor C3 connected in parallel to the output end after being connected in series, the positive phase output end Vo + is connected to the positive end LED + of the LED through a transistor Q2, and the negative phase output end Vo-is connected to the negative end LED-; the positive pole of the diode D1 is connected with the positive phase output end Vo +, the negative pole is connected with the negative pole of the voltage stabilizing diode Z1, the positive pole of the voltage stabilizing diode Z1 is connected with the upper pole plate of the capacitor C3, the upper pole plate of the capacitor C3 is connected with the grid of the transistor Q2 after passing through the resistor R3, and the positive pole of the voltage stabilizing diode Z2 is connected with the positive pole LED + of the LED and the negative pole is connected with the grid of the transistor Q2. The traditional MOSFET ripple removing circuit has better ripple removing effect when the dimming depth is high, but the circuit has larger loss and more efficiency loss when the circuit is fully loaded.

Therefore, how to provide a new ripple removing circuit that improves the ripple removing effect of high dimming depth and simultaneously considers the overall system efficiency has become one of the problems to be solved by those skilled in the art.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a feedback voltage adjusting module, a high dimming depth ripple removing circuit and a method thereof, which are used to solve the problem that the ripple removing effect of improving the high dimming depth and the overall system efficiency cannot be considered at the same time in the prior art.

In order to achieve the above and other related objects, the present invention provides a feedback voltage adjusting module for a ripple removing circuit with a high dimming depth, where the ripple removing circuit includes a ripple removing control tube and a feedback resistor connected to a source end of the ripple removing control tube, and the feedback voltage adjusting module at least includes:

the current detection unit is connected to the source end of the ripple-free control tube and used for detecting the current flowing through the ripple-free control tube and generating a control signal according to the detected current;

and each shunt unit is connected with the feedback resistor of the ripple-removing control tube source end in parallel and is used for adjusting the feedback voltage of the ripple-removing control tube source end according to the current flowing through the ripple-removing control tube.

Preferably, the shunt unit includes a switch tube, a source and a drain of the switch tube are respectively connected to two ends of the feedback resistor, and a gate of the switch tube is connected to an output end of the current detection unit.

Preferably, the shunt unit further includes a shunt resistor, the shunt resistor is connected in series with the switching tube, and the series connection of the voltage resistor and the switching tube is connected in parallel with the feedback resistor.

To achieve the above and other related objects, the present invention provides a high dimming depth de-ripple circuit, which at least includes:

the positive end of the LED load is connected with the output end of the preceding stage circuit;

the drain end of the ripple removing control tube is connected with the negative end of the LED load, and the ripple of the output current is removed by adjusting the current flowing through the ripple removing control tube;

one end of the feedback resistor is connected with the source end of the ripple wave removing control tube, and the other end of the feedback resistor is grounded and is used for converting the output current into voltage;

the ripple removing control module is connected with the negative end of the LED load and the source end of the ripple removing control tube, and controls the grid end of the ripple removing control tube according to the voltage of the negative end of the LED load and the feedback voltage of the source end of the ripple removing control tube;

the feedback voltage adjusting module is connected to a source end of the ripple-free control tube, and raises the feedback voltage in a process that the output current is reduced from a first set current to a minimum output current and is increased from the minimum output current to a second set current, wherein the feedback voltage linearly changes along with the output current.

Preferably, the ripple removal control module comprises a sampling unit, a compensation voltage generation unit and a driving unit; the sampling unit is connected to the negative end of the LED load to obtain the sampling voltage of the negative end of the LED load; the compensation voltage generating unit is connected to the output end of the sampling unit and the source end of the ripple wave removing control tube, and obtains corresponding compensation voltage according to the sampling voltage and the feedback voltage; the driving unit is connected with the output end of the compensation voltage generating unit and the source end of the ripple removing control tube, and controls the ripple removing control tube according to the compensation voltage and the feedback voltage.

More preferably, the ripple removal control module is further connected to a compensation capacitor, and the other end of the compensation capacitor is grounded.

Preferably, the first setting current is smaller than the second setting current.

To achieve the above and other related objects, the present invention provides a method for removing ripples at a high dimming depth, the method at least comprising:

detecting output current during dimming, increasing the resistance value of a resistor for detecting the output current along with the reduction of the output current when the output current is smaller than a first set current so as to raise the feedback voltage of the source end of the ripple removing control tube, controlling the ripple removing control tube to perform constant current control through the feedback voltage and the voltage of the negative end of the LED load, and further removing ripples of the output current;

and when the output current is larger than a second set current, reducing the resistance of a resistor for detecting the output current so as to press down the feedback voltage at the source end of the ripple removing control tube, and controlling the ripple removing control tube to perform constant current control through the feedback voltage and the voltage at the negative end of the LED load so as to remove ripples of the output current.

Preferably, the resistance value of the resistor for detecting the output current is adjusted by adjusting the number or resistance value of shunt resistors connected in parallel with the feedback resistor.

More preferably, the shunt resistance is an on-resistance of a resistor or a MOS transistor.

More preferably, the first setting current is smaller than the second setting current.

More preferably, the method for removing ripples at the high dimming depth further comprises: setting a plurality of set currents, and sequentially raising the feedback voltage in the process of reducing the output current; and sequentially pressing down the feedback voltage in the process of increasing the output current.

As described above, the feedback voltage adjusting module, the ripple removing circuit with high dimming depth and the method of the present invention have the following advantages:

the feedback voltage adjusting module, the high-dimming-depth ripple removing circuit and the method of the invention improve the system efficiency by using the chip ripple removing circuit, and simultaneously have excellent ripple removing adjusting capability under the condition of high dimming depth, thereby greatly improving the performance of the ripple removing circuit.

Drawings

Fig. 1 is a schematic diagram of a chip control ripple-removal chip circuit in the prior art.

Fig. 2 is a schematic diagram of a conventional MOSFET de-ripple circuit in the prior art.

Fig. 3 shows an embodiment of the high dimming depth deglitch circuit of the present invention.

Fig. 4 is a schematic diagram illustrating the principle of the method for removing ripples with high dimming depth according to the present invention.

Fig. 5 shows another embodiment of the high dimming depth deglitch circuit of the present invention.

Fig. 6 shows a high dimming depth deglitch circuit according to another embodiment of the present invention.

Description of the element reference numerals

1 high dimming depth removes ripple circuit

11 ripple wave removing control module

111 compensation voltage generating unit

112 drive unit

12 feedback voltage adjusting module

121 current detection unit

122 shunt unit

13 power supply module

2 preceding stage circuit

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Please refer to fig. 3 to 6. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.