CN201479432U - A Wide Voltage Range Dimmable LED Constant Current Source Driver - Google Patents

Abstract

The utility model discloses a wide voltage range adjustable LED constant current source driver, which belongs to the LED light source driver in the lighting field. The structure of the driver includes: voltage identification circuit, light compensation circuit, MCU control circuit, temperature compensation circuit and adjustable constant current source circuit, wherein: the output terminals of voltage identification circuit, light compensation circuit and temperature compensation circuit are all connected to MCU control The input terminal of the circuit, the PWM output terminal of the MCU control circuit is connected to the input terminal of the dimmable constant current source circuit, the voltage identification circuit and the dimmable constant current source circuit are connected to the DC or AC input voltage, and the light compensation circuit is connected to the photosensitive device , the temperature compensation circuit is connected to the thermistor, and the output terminal of the adjustable light constant current source circuit is connected to the LED light source. The utility model has the advantages of low cost, small size, stable and reliable system operation, and prolongs the service life of the LED.

Description

A Wide Voltage Range Dimmable LED Constant Current Source Driver

technical field

The utility model relates to an LED light source driver in the lighting field, in particular to a wide voltage range dimmable LED constant current source driver.

Background technique

At present, under the background of global energy shortage and the country's vigorous advocacy of energy saving and consumption reduction, with the development of science and technology, the application of LED lighting products is attracting the attention of the world in the field of lighting. Small size, high luminous efficiency and other characteristics, can be widely used in household lighting, road lighting, urban night scenes and other lighting occasions.

The LED light source is driven by a constant current source. At present, there are still defects in the driver technology on the market. The performance is that the input voltage range is narrow, the versatility is poor, and the use of a transformer results in a large and bulky size. Some are constant voltage drivers, resulting in a single LED. A string of LED lamp beads will be damaged due to a short circuit, and the project maintenance cost is high, and the maintenance workload is relatively large, and they do not have the function of adjusting the brightness of the LED according to the ambient light, resulting in a great waste of energy. These are not only detrimental to the promotion and application of LED light sources, but also fail to tap the greatest potential for energy saving and consumption reduction.

Contents of the invention

The technical problem to be solved by the utility model is to propose a wide voltage range dimmable LED constant current source driver for the defects of the LED driver in the background technology.

The utility model wide voltage range dimmable LED constant current source driver, its structure includes: voltage identification circuit, light compensation circuit, MCU control circuit, temperature compensation circuit and adjustable light constant current source circuit, wherein: voltage identification circuit, The output ends of the light compensation circuit and the temperature compensation circuit are both connected to the input end of the MCU control circuit, the PWM output end of the MCU control circuit is connected to the input end of the dimmable constant current source circuit, and the voltage identification circuit and the adjustable light constant current source circuit are connected to each other. The input voltage is connected, the input end of the light compensation circuit is connected to the photosensitive device, the input end of the temperature compensation circuit is connected to the thermistor, and the output end of the adjustable constant current source circuit is connected to the LED light source.

The utility model has the following beneficial effects:

1. The wide-range voltage input capability can save transformers and other devices, with low cost and small size; it is compatible with mains power system and DC power system; external MOSFET circuit can be flexibly configured according to load power consumption, and the heat treatment of the circuit board is convenient and the heat dissipation is good. The system works stably and reliably.

2. DC 18V-450V or AC 110V/220V input voltage range can make the constant current source small, flexible and versatile.

3. The light compensation function can automatically adjust the LED brightness without flickering according to the intensity of the ambient light. When the light is strong in the daytime, the output current is reduced to reduce the LED brightness, and the energy saving effect is obvious. Compared with full power operation without light compensation, it can effectively save energy by 20 %-30%.

4. The temperature compensation function can reduce the volume of the radiator and make the LED work stably in the normal temperature range, prolong the service life, and reduce the cost and engineering maintenance.

Description of drawings

Fig. 1 is a structural principle block diagram of the utility model.

Fig. 2 is a schematic diagram of a dimmable constant current source circuit in the utility model.

Fig. 3 (a) is the schematic diagram of the temperature compensation circuit in the utility model; Fig. 3 (b) is the schematic diagram of the MCU control circuit in the utility model; Fig. 3 (c) is the schematic diagram of the light compensation circuit in the utility model.

Detailed ways

As shown in Figure 1, the structure of the wide voltage range dimmable LED constant current source driver of the present invention includes: a voltage identification circuit, a light compensation circuit, an MCU control circuit, a temperature compensation circuit and a dimmable constant current source circuit, wherein: the voltage The output terminals of the identification circuit, the light compensation circuit and the temperature compensation circuit are all connected to the input terminal of the MCU control circuit, the PWM output terminal of the MCU control circuit is connected to the input terminal of the dimmable constant current source circuit, the voltage identification circuit and the dimmable constant current source circuit The source circuit is connected to DC 18V-450V or AC 110V/220V input voltage, the input end of the light compensation circuit is connected to the photosensitive device, the input end of the temperature compensation circuit is connected to the thermistor, and the output end of the adjustable constant current source circuit is connected to the LED light source.

The dimmable constant current source circuit adopts the professional constant current source chip PT4107 with an efficiency of up to 90%, which is common to both DC and AC. The LED current can be controlled from 0 to normal current state through the PWM signal, that is, the LED brightness can be changed from dark to normal brightness. Flicker adjustment; the light compensation circuit collects ambient light through the photosensitive device, and adjusts the LED brightness according to the light intensity; the temperature compensation circuit adds heat dissipation during use, and adjusts the PWM signal through temperature feedback to make the LED work in a normal temperature range, preventing the LED The performance of the lamp deteriorates and fails due to excessive heat generation; the MCU control circuit adjusts the duty cycle of the output PWM signal according to the collected ambient light, temperature and other information to adjust the brightness of the LED.

The dimmable constant current source circuit is shown in Figure 2. Because of the rectifier bridge D1, the power supply V1 can output AC or DC power normally, and there is no positive or negative for DC power; U1 is a professional constant current source chip PT4107, through Changing the resistor R2 can set the switching frequency of the switching tube Q1, the highest operating frequency can reach 1MHz, which can reduce the size of the external inductor and filter capacitor and improve the efficiency; the thermistor NTC is used to detect the working temperature of the constant current source switching tube Q1, when When the temperature reaches the upper limit, it can be automatically disconnected, and the entire circuit stops working to protect Q1; the pin 1 of the switch tube Q1 is connected to the driving pin of the constant current source chip U1, and the inductance L1 For energy storage, the energy stored in the inductor L1 is discharged through the fast recovery diode D2 during the off-time period when Q1 is turned off to maintain the LED to work; the resistor R3 is used to set the loop current. When the input voltage becomes high, R3 divides If the voltage is higher than 250mV, U1 increases the off-time time of the switch tube Q1 drive signal, that is, increases the off-time of Q1 and reduces the energy storage time of L1, so that the output current is stabilized at the set loop current; the potentiometer PR can adjust the output current Fine-tuning can improve the accuracy of the output current by up to 5%.

The temperature compensation circuit, MCU control circuit, and light compensation circuit are shown in Figure 3. In the figure, the MCU chip U2 uses a chip STC12C5602AD with ADC sampling and PWM output functions. Pins 9 and 11 of the MCU are high-frequency PWM signal output pins. The connection diagram In 2, the EN terminal of U1 performs flicker-free dimming; in the light compensation circuit, a photosensitive device such as a solar panel is used to collect light, and after dividing the voltage by resistors R11 and R12, connect ADOPT to pin 19 of the MCU; in the temperature compensation circuit, the resistor R16 and R17 are negative temperature coefficient thermistors, which are used to collect the working temperature of the LED. TEMP1 and TEMP2 are respectively connected to pins 16 and 17 of the MCU. The collected light and temperature analog quantities are converted into digital quantities through the ADC conversion function of the MCU, and the PWM output is divided into 5 levels of output according to the light intensity. When the light is darkest, the PWM signal is output with a 100% duty cycle. Reduce the duty cycle of the PWM signal at a pace of 8%, and the minimum duty cycle signal is 60% to drive the dimmable constant current source circuit. At this time, the power loss of the LED is half of that when the driving signal is 100%. During the gear output, the MCU continuously collects the working temperature of the LED. When the temperature is higher than the set value, the MCU will reduce the duty cycle of the PWM signal by 1% on the basis of each gear, otherwise it will increase by 1%, so that the LED works at The luminous efficiency is maximized under the premise of an optimal temperature environment, which not only prolongs the working life of the LED, but also reduces the size and cost of the radiator.

Claims (2)

1. Dimmable LED constant current source driver with wide voltage range, it is characterized in that: comprise the voltage identification circuit, the light compensation circuit, the MCU control circuit, temperature-compensation circuit and tunable optical constant-current source circuit, wherein: the voltage identification circuit, the output of light compensation circuit and temperature-compensation circuit all is connected the input of MCU control circuit, the PWM output of MCU control circuit connects the input of tunable optical constant-current source circuit, voltage identification circuit and tunable optical constant-current source circuit all insert input voltage, the input of light compensation circuit connects light-sensitive device, the input of temperature-compensation circuit connects thermistor, and the output of tunable optical constant-current source circuit connects led light source.

2. Dimmable LED constant current source driver with wide voltage range according to claim 1 is characterized in that: described tunable optical constant-current source circuit adopts direct current and the general constant-current source chip of alternating current.

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