CN201601859U - A non-isolated LED drive circuit - Google Patents

Abstract

The utility model discloses a non-isolated LED driving circuit, mainly consisting of an integrated circuit chip U and a load LED, which is characterized in that: an anode of the load LED is connected with an output anode of an AC rectification circuit, and the cathode of the load LED is connected with the integrated circuit chip U through an inductor L1. The AC rectification circuit is also connected with the integrated circuit chip U through a DC output circuit and a potentiometer R1; an anode of a diode D1 is connected with the integrated circuit chip U and the inductor L1, and a cathode of the diode D1 is connected with the anode of the load LED. The whole circuit structure of the utility model is in a non-isolated structure without using the traditional transformer and photoelectric coupler. Therefore, the utility model obviously simplifies the circuit structure, improves the circuit performance, and also reduces the manufacturing cost and maintenance cost.

Description

A non-isolated LED drive circuit

technical field

The utility model relates to a driving circuit, in particular to a non-isolated LED driving circuit.

Background technique

Since the beginning of this century, higher-power light-emitting diodes (LEDs) have been more and more widely used in various lighting and high-brightness display places, such as indoor lighting, venue lighting, display walls, traffic lights, tunnel lighting, underground lighting, etc. Compared with ordinary lighting equipment, the power required to drive LED (or light up LED) is different from that required to drive ordinary lighting equipment. The power supply required for ordinary lighting equipment is a regulated output, and the current changes below the maximum value, while driving LED Generally, a constant current output of the power supply is required, and the voltage varies below the maximum value.

Use AC to represent alternating current power supply (such as 220VAC, 50Hz), use DC to represent regulated direct current, and use CC to represent constant current direct current to drive LEDs, then the power supply circuit scheme can be roughly divided into two categories: the first category is AC/DC+DC/CC Power supply circuit, the second category is AC/CC power supply circuit, and the second category can be divided into two categories, namely isolated and non-isolated. A common LED drive circuit is shown in Figure 1. Since the LED is to be driven, it is necessary to add a "measurement output current" circuit at the output stages of D1 and C3 of the transformer T1 of the LED drive circuit. At the same time, in order to increase the "measurement output Current size" circuit, it is also necessary to add a winding to the transformer T1, so as to make an isolated AC/CC power supply circuit. Therefore, when the technology shown in Figure 1 is used to drive LEDs, the circuit structure is relatively complicated, and the maintenance and production costs are high, which is not conducive to widespread promotion and application.

Utility model content

The purpose of the utility model is to overcome the defects of complex structure and high maintenance and production cost of current LED driving circuits, and provide a non-isolated LED driving circuit with simple circuit structure and low maintenance and production costs.

The purpose of this utility model is achieved through the following technical solutions: a non-isolated LED drive circuit, mainly composed of an integrated circuit chip U and a load LED, the anode of the load LED is connected to the output positive pole of the AC rectifier circuit, and its cathode is The inductor L1 is connected with the integrated circuit chip U; the AC rectifier circuit is also connected with the integrated circuit chip U through the DC output circuit and the potentiometer R1; the anode of the diode D1 is connected with the integrated circuit chip U and the inductor L1, and its The cathode is connected to the anode of the load LED.

Further, the described AC rectification circuit is that one end of the capacitor C3 is connected to the input terminal I of the rectifier bridge D4 through the inductor L2, and the other end of the capacitor C3 is connected to the input terminal II of the rectifier bridge D4 through the fuse F1 ; The positive output end of the rectifier bridge D4 is connected with the negative output end of the rectifier bridge D4 after the capacitor C2, and the negative output end of the rectifier bridge D4 is grounded; between the input I end and the input II end of the rectifier bridge D4, there is also connected Capacitor C4.

Described DC output circuit is, one end of resistor R2 is connected with the input II end of rectifier bridge D4, and its other end is connected with the cathode of diode D2 after capacitor C5; The anode of diode D2 is connected with the negative pole of rectifier bridge D4 The output terminal is connected, and its cathode is connected with the anode of the diode D3; the cathode of the diode D3 is connected with the cathode of the diode D5 through the resistor R3, and the anode of the diode D5 is connected with the GND end of the integrated circuit chip U and the rectifier bridge D4 The negative output terminals are connected; the cathode of the diode D3 is connected to the negative output terminal of the rectifier bridge D4 through the capacitor C6, and the cathode of the diode D3 is also directly connected to the VCC terminal of the integrated circuit chip U.

One end of the potentiometer R1 is connected to the COMP terminal of the integrated circuit chip U through the resistor R4, and the other end of the potentiometer R1 is connected to the cathode of the diode D5. A capacitor C1 is also connected between the input terminal and the output terminal of the load LED.

In order to ensure the use effect, the model of the integrated circuit chip U is AP8012, AP8022 or VIPer22x.

The diode D1 is a fast recovery diode, and the diode D5 is a Zener diode.

Compared with the prior art, the utility model has the following advantages and beneficial effects:

(1) The entire circuit structure of the utility model is a non-isolated structure, which does not need to use traditional transformers and photocouplers, so the utility model not only significantly simplifies the circuit structure, improves the performance of the circuit, but also reduces the production cost and maintenance costs.

(2) When matched with appropriate load LEDs, the utility model can not only replace traditional incandescent lamps, but also replace fluorescent lamps and their ballasts, so the utility model has strong practicability.

Description of drawings

FIG. 1 is a schematic diagram of a circuit structure in the prior art.

Fig. 2 is a block diagram of the overall structure of the utility model.

Fig. 3 is a schematic diagram of the circuit structure of the utility model.

Detailed ways

The utility model will be described in further detail below in conjunction with the embodiments and accompanying drawings, but the implementation of the utility model is not limited thereto.

As shown in Figure 1, the existing LED drive circuit is mainly composed of a rectifier circuit, an integrated circuit chip U, a transformer T1 and a photocoupler. As shown in the figure, one end of the primary side of the transformer T1 is connected to the positive output of the rectifier circuit, and the other end of the primary side is connected to the integrated circuit U; one secondary side of the transformer T1 is connected to a diode and a capacitor, etc., and the integrated circuit U is connected accordingly. The VCC terminal of the photocoupler and the O1D terminal of the photocoupler; the other secondary side of the transformer T1 is connected to the diode D1 and the capacitor C3, etc., and the load LED and the O1E terminal of the photocoupler are connected accordingly.

Since its structural characteristics are far from meeting this requirement when supplying a constant current to the LED, it is necessary to add a circuit for "measuring the output current" at the D1 and C3 output stages of the transformer T1, resulting in a more complicated circuit structure, which is not conducive to Maintenance and crafting, and its performance effect is also relatively poor.

As shown in Figures 2 and 3, the AC rectifier circuit of the present invention is used for outputting high-voltage direct current, and the direct current output circuit is used for outputting small direct current. or VIPer22x integrated circuits. In order to adjust the output current peak value of the integrated circuit chip U, the integrated circuit chip U is also connected with a potentiometer R1.

When connecting, one end of the AC rectifier circuit is connected to the integrated circuit chip U through the DC output circuit and the potentiometer R1, and at the same time, the positive output pole of the AC rectifier circuit is connected to the anode of the load LED, so as to provide normal voltage for the load LED. Work provides electrical energy. At the same time, the cathode of the load LED is also connected to the integrated circuit chip U through the inductor L1, and a fast recovery diode D1 is also connected between the anode of the load LED and the other end of the inductor L1, that is, the load LED and the inductor L1 After being connected in series, it is connected in parallel with the fast recovery diode D1. In order to reduce the ripple current of the load LED, a capacitor C1 is also connected in parallel at both ends of the load LED, that is, the anode of the load LED is connected to the positive output terminal of the rectifier bridge D4, and the cathode of the load LED is connected to the integrated circuit chip after passing through the inductor L1 The SW terminals of U are connected so that the capacitor C1 and the inductor L1 together form a low-pass filter. The anode of the fast recovery diode D1 is connected to the SW terminal of the integrated circuit chip U, and its cathode is connected to the positive output terminal of the rectifier bridge D4. Its specific circuit structure is shown in Figure 3, that is, the AC rectification circuit is composed of capacitor C3, inductor L2, fuse F1, capacitor C4, rectifier bridge D4 and capacitor C2. One end of the capacitor C3 is connected to the input I terminal of the rectifier bridge D4 through the inductor L2, and the other end of the capacitor C3 is connected to the input II terminal of the rectifier bridge D4 through the fuse F1. Meanwhile, the two ends of the capacitor C3 are also connected with a connector AC for AC input.

A capacitor C4 is also connected between the input I terminal of the rectifier bridge D4 and the input II terminal of the rectifier bridge D4, the positive output terminal of the rectifier bridge D4 is connected to the positive pole of the capacitor C2, and the negative pole of the capacitor C2 is connected to the negative pole of the rectifier bridge D4 The output terminal is connected, and defines this negative pole as the local ground.

The DC output circuit is composed of resistors R2 and R3, capacitors C5 and C6, diodes D2 and D3 and Zener diode D5. When connecting, one end of the resistor R2 is connected to the input II end of the rectifier bridge D4, and the other end of the resistor R2 is connected to the anode of the diode D3 after the capacitor C5. The cathode of the diode D2 is directly connected to the anode of the diode D3, and at the same time, the anode of the diode D2 is also connected to the negative output terminal of the rectifier diode D4, that is, the anode of the diode D2 is connected to the local ground.

The cathode of the diode D3 is divided into two paths, one path is connected to the cathode of the Zener diode D5 through the resistor R3, and the other path is connected to the anode of the capacitor C6, and the cathode of the capacitor C6 is connected to the local ground. At the same time, the cathode of the diode D3 is also directly connected to the VCC terminal of the integrated circuit chip U. In order to adjust the peak value of the output current of the integrated circuit chip U and realize the function of adjusting the brightness of the load LED, a potentiometer R1 is also connected to the integrated circuit chip U, that is, the output of the potentiometer R1 can be adjusted by adjusting the resistance value of the potentiometer R1. current. When connected, one end of the potentiometer R1 is connected to the cathode of the Zener diode D5, and the other end of the potentiometer R1 is connected to the COMP end of the integrated circuit chip U through the resistor R4. The GND end of the integrated circuit chip U is also connected to the anode of the Zener diode D5, and the GND ends are all connected to the local ground.

As mentioned above, the utility model can be better realized.

Claims (8)

1. A non-isolated LED drive circuit, mainly composed of an integrated circuit chip U and a load LED, characterized in that: the anode of the load LED is connected to the output positive pole of the AC rectifier circuit, and its cathode is connected to the integrated circuit through an inductor L1 The chip U is connected; the AC rectifier circuit is also connected to the integrated circuit chip U through the DC output circuit and the potentiometer R1; the anode of the diode D1 is connected to the integrated circuit chip U and the inductor L1, and its cathode is connected to the anode of the load LED connected. 2. a kind of non-isolated LED drive circuit according to claim 1, is characterized in that: described AC rectification circuit is, one end of capacitor C3 is connected with the input I terminal of rectifier bridge D4 after inductor L2, The other end of the capacitor C3 is connected to the input II terminal of the rectifier bridge D4 through the fuse F1; the positive output terminal of the rectifier bridge D4 is connected to the negative output terminal of the rectifier bridge D4 after passing through the capacitor C2, and the negative output terminal of the rectifier bridge D4 grounding; a capacitor C4 is also connected between the input I terminal and the input II terminal of the rectifier bridge D4. 3. A non-isolated LED drive circuit according to claim 2, characterized in that: the DC output circuit is that one end of the resistor R2 is connected to the input II end of the rectifier bridge D4, and the other end is connected to the input terminal II of the rectifier bridge D4. The capacitor C5 is connected to the cathode of the diode D2; the anode of the diode D2 is connected to the negative output terminal of the rectifier bridge D4, and its cathode is connected to the anode of the diode D3; the cathode of the diode D3 is connected to the cathode of the diode D5 through the resistor R3 The anode of the diode D5 is connected to the GND terminal of the integrated circuit chip U and the negative output terminal of the rectifier bridge D4; the cathode of the diode D3 is connected to the negative output terminal of the rectifier bridge D4 after passing through the capacitor C6, and the diode The cathode of D3 is also directly connected to the VCC terminal of the integrated circuit chip U. 4. A non-isolated LED drive circuit according to claim 3, characterized in that: one end of the potentiometer R1 is connected to the COMP end of the integrated circuit chip U through a resistor R4, and the potentiometer R1 The other end is connected to the cathode of the diode D5. 5. A non-isolated LED driving circuit according to claim 1, wherein a capacitor C1 is further connected between the input terminal and the output terminal of the load LED. 6. A non-isolated LED driving circuit according to any one of claims 1-5, characterized in that: the model of the integrated circuit chip U is AP8012, AP8022 or VIPer22x. 7. A non-isolated LED driving circuit according to claim 6, wherein said diode D1 is a fast recovery diode. 8. A non-isolated LED driving circuit according to claim 3, wherein the diode D5 is a Zener diode.

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