Patent ID: 8766560

Claim:
An adaptive LED (light emitting diode) dimming driving circuit, installed to a lamp board, for driving and linearly regulating an illumination brightness of at least an LED, and disposed with a dimming module, a rectification module and a control module, whereby the rectification module is electrically connected to an external power source through the dimming module, the control module is electrically connected to the rectification module and the LED, the control module having a control chip, a regulator and a sensing resistor, the LED is coupled to the control chip through the regulator and the sensing resistor, which are cascaded so that a sensing value is fed back to the control chip after the sensing resistor senses a driving current I LED flowing through the LED, a reference value is utilized to compare with the sensing value to control the regulator to regulate the driving current I LED , characterized in that the adaptive LED dimming driving circuit comprises: the rectification module coupled to the dimming module through a regulator capacitor connected in parallel, the control module disposed with a first resistor, a second resistor, a retainer, a third resistor and a fourth resistor, the retainer electrically connected to the rectification module, the first resistor, the second resistor and the control chip, wherein the first resistor coupled to the second resistor and the control chip; the third resistor electrically connected to the rectification module and the control chip, one end of the fourth resistor coupled to the LED and the control chip while another end of the fourth resistor is coupled to the regulator and the sensing resistor, wherein when the rectification module outputs an input voltage to form an input current the control chip drives the retainer to outputs a retaining current I hold to the second resistor so that the input voltage is consumed by the second resistor to retain a normal work of the dimming module, the first resistor dividing the input voltage to allow the control chip to detect a dimming intensity of the dimming module real-time such that under a condition of allowing the input current satisfying a correlation I in =I hold +I LED , the retaining current having a minimum current value to increase a work efficiency when the LED is regulated to a maximum brightness; wherein when the input voltage raises, an across voltage at two ends of the fourth resistor is increased to compensate an across voltage at two ends of the sensing resistor so that the driving current I LED is reduced to achieve a constant power state, and the third resistor divides voltages and detects a ripple value of the input voltage, and when the input voltage is reduced and the ripple value is smaller than a standard value, the control chip reduces the reference value to prevent the LED from generating twinkling phenomenon.