Adjustable brightness module and LED drive system with adjustable brightness

Abstract

A brightness-adjustable module comprises a first state detection comparator, a second state detection comparator and a peak current comparator, wherein the negative input end of the first state detection comparator is connected with the first input end of the brightness-adjustable module through a voltage division unit, and the output end of the first state detection comparator is connected with a state machine so as to output a first state signal to the state machine; the positive input end of the second state detection comparator is connected with the first input end through a voltage division unit, and the output end of the second state detection comparator is connected with the state machine so as to output a second state signal to the state machine; the negative input end of the peak current comparator is connected with the state machine, the positive input end of the peak current comparator is connected with a source electrode of a power switch and an external detection unit, the output end of the peak current comparator is connected with the state machine so as to output a third state signal to the state machine; the state machine is connected with a grid electrode of the power switch through a driver, the source electrode of the power switch serves as the output end of the brightness-adjustable module, and the state machine outputs control signals to control the on-off state of the power switch according to the first state signal and the second state signal and controls the peak value of current passing through the power switch through the third state signal. Accordingly, the power switch controls a loading LED to work in different kinds of brightness.

Description

technical field [0001] The invention relates to the field of LED driving, in particular to an adjustable brightness module and an adjustable brightness LED driving system. Background technique [0002] see figure 1 , a simplified schematic diagram of a prior art flyback LED drive circuit. Such as figure 1 As shown, the input AC power supply 101 is connected to the two input terminals of the rectifier bridge 103; the rectifier bridge 103 rectifies the alternating current and filters it through the input capacitor C1 to generate a DC voltage; the starting resistor Rst and the starting capacitor C2 generate a low-voltage direct current to drive the Chip 105 starts up. The transformer T1 has two to three windings, including a primary winding connected between the input capacitor C1 and the drain DRAIN of the driver chip 105; a secondary winding connected between the anode of the freewheeling diode D1 and the cathode of the output capacitor C3 In between, the cathode of the f...

AI Technical Summary

Problems solved by technology

[0003] The LED lamp using the above-mentioned LED driving circuit has a single and fixed light output brightness, and it is impossible to achieve multiple brightness adjustments for the LED lamp

Images