CN201440745U - LED current limiting circuit - Google Patents

Abstract

The utility model discloses a LED current-limiting circuit, including power, switch, power conversion circuit, filter circuit, current switch control drive circuit and the load that connects gradually power conversion circuit output and load LED between establish ties and have inserted current-limiting circuit, current-limiting circuit constitute by resistance, its with the load series connection be in power conversion circuit output with between the current switch control drive circuit output, the utility model discloses LED current-limiting circuit constant voltage constant current output can realize the restriction to load current through adjusting the size of current-limiting resistance, compares with other circuits that do not add this current-limiting resistance, can effectively prolong the life-span and the luminous time of LED lamp under the condition of same power energy; the utility model discloses the circuit, the circuit is simple, low cost, and it is convenient to connect, and the combination of being convenient for is used, no longer needs other power after the installation, and is energy-concerving and environment-protective.

Description

LED current limiting circuit

technical field

The utility model relates to LED lighting technology, in particular to an LED current limiting circuit for lighting realized by resistors.

Background technique

With the continuous improvement of people's lives, people also dress up the cities they live in. More and more LED lights are dotted with large and small buildings in the city and green belts everywhere, outlining the beautiful landscape of the city. However, it has been found that the common LED lamp power supply is obtained by rectification and current limiting of the mains. The circuit and safety measures are relatively complicated, the cost is high, it is difficult to control, and the effect of voltage stabilization and current limiting is not ideal. When the voltage is unstable Sometimes, LED lights are easy to burn out. At the same time, due to unstable voltage and large current changes, the life of LED lights is greatly reduced. This is also a major defect of ordinary LED lights. Although some products use low-voltage mobile power supply and constant voltage output, because of the lack of relevant current limiting measures, it is difficult to guarantee the life of the LED, and the continuous light-emitting time of the product is very short, which is difficult to meet the application.

Utility model content

The purpose of this utility model is to provide a simple and low-cost LED current limiting circuit for the above disadvantages.

The purpose of this utility model is achieved through the following technical solutions:

An LED current limiting circuit, comprising a power supply, a switch, a power conversion circuit, a filter circuit, a current switch control drive circuit and a load connected in sequence, and a current limiting circuit is connected in series between the output terminal of the power conversion circuit and the load LED The current limiting circuit is composed of a resistor, which is connected in series with the load between the output end of the power conversion circuit and the output end of the current switch control drive circuit.

The power supply is composed of a diode D1, a solar panel battery and a rechargeable battery. The connection mode is: the batteries are connected in parallel, and the positive and negative poles of the diode D1 are respectively connected in series with the positive pole of the solar panel battery and the positive pole of the rechargeable battery.

The load is an LED, which is connected in series between the output end of the power conversion circuit and the output end of the current switch control drive circuit.

The load is a parallel group of LEDs, which are connected in series between the output end of the power conversion circuit and the output end of the current switch control drive circuit.

The filter circuit is a capacitor filter circuit, which is composed of a capacitor C1 connected in parallel in the circuit.

The power conversion circuit is a step-up power conversion circuit, which includes an inductor L1, a diode D2, and a chip U1. The connection method is: the inductor L1 and the diode D2 are connected in series between the power supply and the filter circuit, and the third The first pin and the second pin are connected in parallel to the positive and negative poles of the diode D2, which are respectively the input and output ends of the power conversion circuit.

The power supply is a battery pack power supply, which is composed of a solar panel battery and a rechargeable battery, and a diode is connected in series between the positive pole of the solar panel battery and the positive pole of the rechargeable battery.

The current switch control driving circuit is composed of a photosensitive resistor R1, ordinary resistors R2, R3, and triodes Q1, Q2. Between poles; the base of transistor Q1 is connected to the series node of resistors R1 and R2; the load LED is connected in series with current limiting resistor R4, and its negative pole is connected to the collector of transistor Q2; resistors R1, R4, positive pole of filter capacitor C1, Q1 emission The pole is connected in parallel with the output terminal of the power conversion circuit; the emitter of the triode Q2, the resistor R2, the negative pole of the filter capacitor C1, the first pin of the chip U1 and the negative pole of the battery are connected in parallel.

The beneficial effects of the utility model are:

1. The circuit of the utility model is simple, low in cost, and the working current is limited by the resistor, and the current is controllable. Compared with other circuits without current limiting resistors, the working life of the product can be effectively extended.

2. The circuit connection of the utility model is simple, and a single battery can work effectively, which is convenient for movement and combined application.

3. The constant voltage and constant current output of the circuit of the utility model can realize the limitation of the LED load current by adjusting the size of the current limiting resistor, which is easy to realize and convenient to adjust.

4. The utility model is powered by solar panel batteries and rechargeable batteries, and the power supply is reliable; the current is controlled by a photoresistor. When the light is strong during the day, the circuit does not work, and the circuit works when the light is weak at night. After installation, it is no longer needed Consumption of other energy, energy saving and environmental protection.

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

Description of drawings

Fig. 1 is the schematic circuit diagram of the utility model.

Detailed ways

Referring to Fig. 1, an LED current limiting circuit provided by this embodiment includes a power supply I, a switch II, a power conversion circuit III, a filter circuit IV, a current switch control driving circuit V, a current limiting circuit VI and a load VII connected in sequence .

The current limiting circuit is composed of resistor R4, and the load is LED; the power supply is composed of diode D1, solar panel battery and rechargeable battery. The positive electrodes of the battery are connected in series; S1 is a switch, and capacitor C1 is a filter capacitor of the filter circuit;

The boost power conversion circuit mainly composed of chip U1 is connected in parallel in the circuit, which includes inductor L1, diode D2, and chip U1. The connection method is: switch S1, inductor L1 and diode D2 are connected in series between the power supply and the filter circuit. The third pin and the second pin of the chip U1 are connected in parallel to the positive and negative poles of the diode D2, which are respectively the input and output ends of the power conversion circuit;

The current switch control driving circuit is composed of photosensitive resistor R1, ordinary resistors R2, R3, and transistors Q1, Q2. The connection method is: R1, R2 are connected in series, and resistor R3 is connected in series between the collector of transistor Q1 and the base of transistor Q2. ; The base of the transistor Q1 is connected to the series node of the resistors R1 and R2; the load LED is connected in series with the current limiting resistor R4, and its negative pole is connected to the collector of the transistor Q2; the resistors R1, R4, the positive pole of the filter capacitor C1, and the emitter of Q1 are connected to the power supply The output terminals of the conversion circuit are connected in parallel; the emitter of the triode Q2, the resistor R2, the negative pole of the filter capacitor C1, the first pin of the chip U1 and the negative pole of the battery are connected in parallel.

When the daylight is strong, the solar panel battery receives sunlight and converts it into electrical energy and charges the rechargeable battery through the diode D1. When the switch S1 is closed, the battery voltage is boosted and stabilized by the boost power conversion circuit. C1 filter output, because the resistance of the photoresistor R1 is small at this time, the triode Q1 and Q2 are not conducting, in the series circuit composed of the current limiting resistor R4 and the load LED, there is no current flowing, and the LED does not emit light; when the night light When it is weak, close the switch S1, because the diode D1 is connected to the circuit to protect the solar panel battery, the rechargeable battery voltage cannot reverse charge the solar panel battery, and the boost power conversion circuit boosts and stabilizes the input voltage, The output is filtered by the capacitor C1 to meet the working power requirements of the LED. The resistance of the photosensitive resistor R1 is relatively large at this time, and the transistors Q1 and Q2 are both saturated and turned on. Q2. The negative electrode of the battery forms a loop, and the LED lights up. Because the output terminal of the boost power conversion circuit is a constant voltage and constant current output, the triode Q2 is saturated and turned on. In this way, by adjusting the resistance value of the current limiting resistor R4, the flow through the load LED can be easily adjusted. The current value of the LED makes the current of the LED constant, and its luminous brightness is basically consistent. Compared with other circuits without the current limiting resistor, it can effectively prolong the life and luminous time of the LED lamp.

As described in the implementation mode of the present utility model, for those of ordinary skill in the art, without spending creative labor, other evolutionary circuits identical or similar to the present utility model are made on the basis of the above-mentioned embodiments, all of which are protected by the present utility model. within range.

Claims (8)

1. LED current-limiting circuit, comprise the power supply, switch, power converting circuit, filter circuit, current switch control Driver Circuit and the load that connect successively, it is characterized in that: between described power converting circuit output and load LED, connect and inserted current-limiting circuit, described current-limiting circuit is to be made of resistance, and itself and described load are connected in series between described power converting circuit output and the described current switch control Driver Circuit output.

2. LED current-limiting circuit according to claim 1, it is characterized in that: described power supply is made of diode D1, solar panels battery and rechargeable battery, its connected mode is: described battery is connected in parallel, and corresponding respectively described solar panels anode of the both positive and negative polarity of described diode D1 and described rechargeable battery positive pole are connected in series.

3. LED current-limiting circuit according to claim 1 is characterized in that: described load is LED, and it is connected in series between described power converting circuit output and the described current switch control Driver Circuit output.

4. LED current-limiting circuit according to claim 1 is characterized in that: described load is LED and joint group, and it is connected between described power converting circuit output and the described current switch control Driver Circuit output.

5. LED current-limiting circuit according to claim 1 is characterized in that: described filter circuit is a capacitor filter, is connected in parallel in the circuit by described capacitor C 1 to constitute.

6. LED current-limiting circuit according to claim 1, it is characterized in that: described power converting circuit is the booster power translation circuit, it comprises inductance L 1, diode D2, chip U1, its connected mode is: described inductance L 1 and described diode D2 are connected between described power supply and the described filter circuit, the 3rd pin of described chip U1, the 2nd pin are connected in parallel corresponding to described diode D2 both positive and negative polarity, are respectively the input and output two ends of described power converting circuit.

7. LED current-limiting circuit according to claim 1, it is characterized in that: described power supply is a battery power, it is made of described solar panels battery and described rechargeable battery, and described diode D1 connects between described solar panels anode and described rechargeable battery positive pole.

8. LED current-limiting circuit according to claim 1, it is characterized in that: described current switch control Driver Circuit is by photo resistance R1, conventional, electric-resistance R2, R3, triode Q1, Q2 form, its connected mode is: described R1, R2 are connected in series, and described resistance R 3 is series between the base stage of the collector electrode of described triode Q1 and described triode Q2; The base stage of described triode Q1 is connected in the series connection node of described resistance R 1, R2; Described load LED and described current-limiting resistance R4 are connected in series, and its described negative pole is connected with described triode Q2 collector electrode; Described resistance R 1, R4, described filter capacitor C1 positive pole, described Q1 emitter are in parallel with described power converting circuit output; Described triode Q2 emitter, described resistance R 2, described filter capacitor C1 negative pole, described chip U1 the 1st pin and described battery cathode are connected in parallel together.