DC-DC boost circuit for LED illumination

Abstract

The utility model discloses a DC-DC boost circuit used for LED illumination, which adopts a three-pin inductor realized by a first coil and a second coil to replace a traditional two-pin inductor of a single coil, and connects a drain electrode of an MOS tube in a switch control circuit to a second connecting end of the inductor, that is, the drain electrode of the MOS tube is connected with an output end of the DC-DC boost circuit through the second coil. At the moment, the maximum voltage capable of being output by the output end of the DC-DC booster circuit is related to the turn number ratio N of the second coil to the first coil, N = N2 / N1, N1 is the coil turn number of the first coil, N2 is the coil turn number of the second coil, the larger N is, the higher the maximum voltage capable of being output by the output end of the DC-DC booster circuit is, and the larger N is. The value of N is set, so that the maximum voltage output by the output end of the DC-DC booster circuit can exceed the withstand voltage of the MOS tube; the driving circuit has the advantages that the driving circuit can be used for driving the LED light-emitting module with the working voltage higher than that of the MOS tube withstand voltage in the switch control circuit, and the application range is wide.

Description

Technical Field

[0001] The utility model relates to a DC-DC boost circuit, in particular to a DC-DC boost circuit used for LED lighting. Background Art

[0002] In LED lamps powered by batteries or low-voltage DC power supplies, a DC-DC boost circuit is often required. The existing DC-DC boost circuit for LED lighting has an input terminal, an output terminal and a cathode. The DC-DC boost circuit converts the DC voltage connected between its input terminal and the cathode through a boost conversion, and outputs a higher DC voltage or DC current between its output terminal and the cathode to drive the LED light-emitting module in the LED lamp to emit light.

[0003] like Figure 1 As shown, the commonly used DC-DC boost circuit for LED lighting generally includes an inductor L, a rectifier diode D, a filter capacitor C and a switch control circuit U having a MOS tube Q. The switch control circuit U has a positive electrode, a negative electrode and a switch output end. The MOS tube Q is used to realize the switch function of the switch control circuit U. The drain of the MOS tube Q is connected to the switch output end of the switch control circuit U. The positive electrode of the switch control circuit U is connected to one end of the inductor L, and its connection end is the input end of the DC-DC boost circuit. The other end of the inductor L and the positive electrode of the rectifier diode D are connected to the switch output end of the switch control circuit U. The negative electrode of the rectifier diode is connected to one end of the filter capacitor C, and its connection end is the output end of the DC-DC boost circuit. The other end of the filter capacitor C is connected to the negative electrode of the switch control circuit U, and its connection end is the negative electrode of the DC-DC boost circuit.

[0004] In the above-mentioned DC-DC boost circuit for LED lighting, since the drain of the MOS tube Q inside the switch control circuit U is directly connected to the positive electrode of the rectifier diode D, when the rectifier diode D is turned on, the voltage at the output end of the DC-DC boost circuit is the same as the drain voltage of the MOS tube Q inside the switch control circuit U. In order to ensure the normal operation of the switch control circuit U, the voltage outputted by the output end of the above-mentioned DC-DC boost circuit must be lower than the withstand voltage of the MOS tube Q inside the switch control circuit U. However, this also results in that the DC-DC boost circuit cannot be used to drive an LED light-emitting module whose operating voltage is higher than the withstand voltage of the MOS tube Q inside the switch control circuit U, and its application is greatly limited. Summary of the invention

[0005] The technical problem to be solved by the utility model is to provide a DC-DC boost circuit for LED lighting which can be used to drive an LED light-emitting module whose working voltage is higher than the withstand voltage of a MOS tube inside its switch control circuit and has a wide application range.

[0006] The technical solution adopted by the utility model to solve the above technical problems is: a DC-DC boost circuit for LED lighting, comprising an inductor, a first diode, a first capacitor and a switch control circuit with a MOS tube, the switch control circuit having a positive electrode, a negative electrode and a switch output end, the MOS tube is used to realize the switch function of the switch control circuit, the drain of the MOS tube is connected to the switch output end of the switch control circuit, the first diode is a rectifier diode, the negative electrode of the first diode is connected to one end of the first capacitor, and the connection end thereof is the output end of the DC-DC boost circuit, the other end of the first capacitor is connected to the negative electrode of the switch control circuit, and the connection end thereof is the output end of the DC-DC boost circuit, and the other end of the first capacitor is connected to the negative electrode of the switch control circuit, and the connection end thereof is the output end of the DC-DC boost circuit. The negative pole of the DC-DC boost circuit, the inductor is a three-pin inductor with three connection ends, the inductor includes a first coil and a second coil, one end of the first coil is the first connection end of the inductor, the other end of the first coil is connected to one end of the second coil, and its connection end is the second connection end of the inductor, the other end of the second coil is the third connection end of the inductor, the positive pole of the switch control circuit is connected to the first connection end of the inductor, and its connection end is the input end of the DC-DC boost circuit, the second connection end of the inductor is connected to the switch output end of the switch control circuit, and the third connection end of the inductor is connected to the positive pole of the first diode.

[0007] The DC-DC boost circuit for LED lighting also includes a second diode, a first resistor and a second capacitor, the second diode is a rectifier diode, the anode of the second diode is connected to the second connection end of the inductor, the cathode of the second diode, one end of the first resistor and one end of the second capacitor are connected, and the other end of the first resistor and the other end of the second capacitor are both connected to the first connection end of the inductor.

[0008] Compared with the prior art, the utility model has the advantage that a three-pin inductor realized by a first coil and a second coil is used to replace a two-pin inductor of a traditional single coil, and the drain of the MOS tube inside the switch control circuit is connected to the second connection end of the inductor, that is, the drain of the MOS tube and the output end of the DC-DC boost circuit are connected through the second coil. At this time, the maximum voltage that can be output by the output end of the DC-DC boost circuit is also related to the turns ratio N of the second coil and the first coil, N=N2 / N1, N1 is the number of turns of the first coil, and N2 is the number of turns of the second coil. The larger N is, the higher the maximum voltage that can be output by the output end of the DC-DC boost circuit is, that is, by setting the value of N, the maximum voltage output by the output end of the DC-DC boost circuit can exceed the withstand voltage of the MOS tube. Therefore, the DC-DC boost circuit for LED lighting of the utility model can be used to drive an LED light-emitting module whose working voltage is higher than the withstand voltage of the MOS tube inside its switch control circuit, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 A circuit diagram of an existing DC-DC boost circuit for LED lighting;

[0010] Figure 2 This is a circuit diagram of a DC-DC boost circuit for LED lighting according to Embodiment 1 of the utility model;

[0011] Figure 3 This is a circuit diagram of a DC-DC boost circuit for LED lighting according to Embodiment 2 of the present utility model. DETAILED DESCRIPTION

[0012] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0013] Example: Figure 2As shown, a DC-DC boost circuit for LED lighting includes an inductor L1, a first diode D1, a first capacitor C1 and a switch control circuit U1 having a MOS tube Q1, the switch control circuit U1 has a positive electrode, a negative electrode and a switch output end, the MOS tube Q1 is used to realize the switch function of the switch control circuit U1, the drain of the MOS tube Q1 is connected to the switch output end of the switch control circuit U1, the first diode D1 is a rectifier diode, the cathode of the first diode D1 is connected to one end of the first capacitor C1, and the connection end is the output end of the DC-DC boost circuit, the other end of the first capacitor C1 is connected to the cathode of the switch control circuit U1, and the connection end is the output end of the DC-DC boost circuit The negative pole of the voltage boost circuit is connected to the inductor L1, the inductor L1 is a three-pin inductor with three connection ends, the inductor L1 includes a first coil N1 and a second coil N2, one end of the first coil N1 is the first connection end of the inductor L1, the other end of the first coil N1 is connected to one end of the second coil N2, and its connection end is the second connection end of the inductor L1, the other end of the second coil N2 is the third connection end of the inductor L1, the positive pole of the switch control circuit U1 is connected to the first connection end of the inductor L1, and its connection end is the input end of the DC-DC boost circuit, the second connection end of the inductor L1 is connected to the switch output end of the switch control circuit U1, and the third connection end of the inductor L1 is connected to the positive pole of the first diode D1.

[0014] In this embodiment, a three-pin inductor implemented by the first coil N1 and the second coil N2 is used to replace the two-pin inductor L1 of the traditional single coil, and the drain of the MOS tube Q1 inside the switch control circuit U1 is connected to the second connection end of the inductor L1, that is, the drain of the MOS tube Q1 and the output end of the DC-DC boost circuit are connected through the second coil N2. At this time, the maximum voltage that can be output by the output end of the DC-DC boost circuit is also related to the turns ratio N of the second coil and the first coil, N=N2 / N1, N1 is the number of turns of the first coil N1, N2 is the number of turns of the second coil N2, and the larger N is, the higher the maximum voltage that can be output by the output end of the DC-DC boost circuit is, that is, by setting the value of N, the maximum voltage output by the output end of the DC-DC boost circuit can exceed the withstand voltage of the MOS tube Q1, so that the DC-DC boost circuit can be used to drive an LED light-emitting module whose working voltage is higher than the withstand voltage of the MOS tube Q1 inside the switch control circuit U1, and has a wide range of applications.

[0015] Embodiment 2: This embodiment is basically the same as Embodiment 1, except that: Figure 3As shown, in this embodiment, the DC-DC boost circuit for LED lighting further includes a second diode D2, a first resistor R1 and a second capacitor C2, the second diode D2 is a rectifier diode, the anode of the second diode D2 is connected to the second connection end of the inductor L1, the cathode of the second diode D2, one end of the first resistor R1 and one end of the second capacitor C2 are connected, and the other end of the first resistor R1 and the other end of the second capacitor C2 are both connected to the first connection end of the inductor L1.

[0016] In this embodiment, the second diode D2, the first resistor R1 and the second capacitor C2 form an RCD absorption circuit to absorb the glitch voltage that may be generated by the inductor L1 when the MOS tube Q1 is switched from on to off, thereby further improving the reliability of the MOS tube Q1 during operation.

Claims

1. A DC-DC boost circuit for LED lighting, comprising an inductor, a first diode, a first capacitor and a switch control circuit having a MOS tube, wherein the switch control circuit has a positive electrode, a negative electrode and a switch output end, the MOS tube is used to realize the switch function of the switch control circuit, the drain of the MOS tube is connected to the switch output end of the switch control circuit, the first diode is a rectifier diode, the negative electrode of the first diode is connected to one end of the first capacitor, and the connection end thereof is the output end of the DC-DC boost circuit, the other end of the first capacitor is connected to the negative electrode of the switch control circuit, and the connection end thereof is the negative electrode of the DC-DC boost circuit, characterized in that The inductor is a three-pin inductor with three connection ends. The inductor includes a first coil and a second coil. One end of the first coil is the first connection end of the inductor. The other end of the first coil is connected to one end of the second coil, and its connection end is the second connection end of the inductor. The other end of the second coil is the third connection end of the inductor. The positive electrode of the switch control circuit is connected to the first connection end of the inductor, and its connection end is the input end of the DC-DC boost circuit. The second connection end of the inductor is connected to the switch output end of the switch control circuit. The third connection end of the inductor is connected to the positive electrode of the first diode.

2. A DC-DC boost circuit for LED lighting according to claim 1, characterized in that It also includes a second diode, a first resistor and a second capacitor, wherein the second diode is a rectifier diode, the anode of the second diode is connected to the second connection end of the inductor, the cathode of the second diode, one end of the first resistor and one end of the second capacitor are connected, and the other end of the first resistor and the other end of the second capacitor are both connected to the first connection end of the inductor.

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