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Dimmable LED driver chip provided with soft start and under-voltage lock-out circuits

An undervoltage lockout circuit and LED driving technology, which is applied in the direction of electric light source, lamp circuit layout, light source, etc., can solve the problems of surge current, LED luminous brightness cannot be adjusted, and limit the application range of LED.

Active Publication Date: 2014-07-16
WUHAN UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The traditional LED driver is a DC-DC converter with constant current output, and its output current is a fixed value. The luminance of the driven LED must not be adjustable, which limits the application range of the LED; due to the inherent characteristics of the DC-DC control loop , when the driver starts, the control loop is in an unbalanced state, so that the system will generate overshoot voltage and surge current, which will easily damage the LED lamp and the LED driver chip; at the same time, during normal operation, because the voltage of the input power supply of the LED driver will change, When the input voltage is low, the LED driver will output a wrong signal, and the LED light will be unreliable and may be damaged

Method used

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  • Dimmable LED driver chip provided with soft start and under-voltage lock-out circuits
  • Dimmable LED driver chip provided with soft start and under-voltage lock-out circuits
  • Dimmable LED driver chip provided with soft start and under-voltage lock-out circuits

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Embodiment

[0026] In order to explain the purpose, technical solutions and advantages of the present invention more clearly, the present invention will be further described below in conjunction with the accompanying drawings and examples.

[0027] attached figure 1 Shown is a typical working circuit of the designed dimmable LED driver with soft-start and under-voltage lockout circuit. It is characterized in that the LED driver chip includes the following six pins: power supply pin VIN, overvoltage protection input pin OVP, inductor current input pin LX, voltage feedback pin FB, dimming signal input pin EN, ground pin GND . The positive terminal of the power supply VDD is connected to the VIN pin to supply power to the chip, and the positive terminal of VDD passes through the input capacitor C IN ground, C IN It can filter out the high-frequency noise in VDD; the inductor L is connected between the VIN pin and the LX pin, the LX pin is connected to the anode of the rectifier diode D, a...

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Abstract

The invention belongs to the field of LED drivers, and relates to a dimmable LED driver chip, in particular to a dimmable LED driver chip provided with soft start and under-voltage lock-out (UVLO) circuits. The chip is based on a current PWM mode DC-DC boost converter. A switch type PWM dimming strategy is adopted for the interior of the chip so that the brightness of an LED lamp can be adjusted smoothly in a wide-range and dispersion-free mode without influencing the efficiency of the chip. Furthermore, the novel soft start circuit is integrated with the chip and can restrain surge currents and overshoot voltages during starting to protect the LED lamp and the driver chip from damage. Finally, the novel UVLO circuit is integrated with the chip to guarantee the working stability of the LED driver chip when the voltage of a power supply changes while the area of the chip is reduced, and the reliability of light emission of the LED is ensured.

Description

technical field [0001] The invention belongs to the field of LED drivers and relates to a dimmable LED driver chip, in particular to a dimmable LED driver chip with a soft start and undervoltage lockout circuit. Background technique [0002] With the development of society, the concept of energy saving is deeply rooted in the hearts of the people, and people are actively looking for high-efficiency light sources, which have achieved the purpose of energy saving. White light LED has become an excellent solid-state light source due to its high luminous efficiency, long service life, good environmental adaptability, smooth dimming performance and other advantages. White LEDs are widely used in off-line lighting, such as indoor lighting fixtures and backlights for liquid crystal displays. Usually multiple LED lamps are connected in series to ensure that the brightness of each LED lamp is the same, while improving the overall brightness. Since the luminous brightness of the LED...

Claims

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Application Information

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IPC IPC(8): H05B37/02
CPCY02B20/40
Inventor 江金光谭高建
Owner WUHAN UNIV
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