A switch segment dimming circuit for led drive
A technology of LED driving and segmented dimming, applied in the direction of electric light circuit layout, light source, electric light source, etc., can solve the problems of increasing the difficulty of LED lamps, LED lamps flickering, increasing harmonic coefficients, etc., to avoid flicker problems and electromagnetic the effect of interference
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Embodiment 1
[0026] Such as figure 1 As shown, the first embodiment of the switch segment dimming circuit for LED driving in the present invention, the switch segment dimming circuit for LED driving includes a voltage power-off detection resistor R1, a detection Signal filter capacitor C2, a Zener diode ZD1, a power failure detection circuit, a power failure cycle counting circuit, a maintenance voltage generation circuit, a voltage maintenance capacitor C3, a gear selection circuit and an output current control circuit. One end of the voltage detection resistor R1 is connected to the positive pole of the rectifier bridge output, the other end of R1 is connected to the positive pole of the detection signal filter capacitor C2, the negative pole of the Zener diode ZD1 and the input end of the power failure detection circuit, and the detection signal filter capacitor C2 The negative pole and the positive pole of the Zener diode ZD1 are grounded; the output terminal of the power failure detec...
Embodiment 2
[0031] Such as figure 2 As shown, the second embodiment of the switch segment dimming circuit for LED driving according to the present invention, the difference between the second embodiment and the first embodiment is that the power supply pin VIN of the chip is separated from the power failure detection pin VDET The power failure detection resistor R1 and detection signal filter capacitor C2 are separated from the power supply resistor R2 and power supply filter capacitor C4 of the application circuit, and one end of the power failure detection resistor R1 is directly connected to one end of the AC input power supply.
Embodiment 3
[0033] Such as image 3 As shown, the third embodiment of the switching segmental dimming circuit for LED driving according to the present invention, the power input of the third embodiment is a DC input, and rectifier diodes D1-D4 are not required, and power supply resistors and power supply filter capacitors are not required. , no need for power failure detection resistors and detection signal filter capacitors, the input power is directly input to the power failure detection circuit after the switch K1 for power failure detection, and at the same time input to the chip to supply power to the internal circuit for other circuits.
[0034] Such as Figure 4As shown, it is an implementation circuit diagram of the power failure cycle counting circuit in the switch segment dimming circuit for LED driving according to the present invention, and the required number of D flip-flops is determined according to the required number of dimming gears. If n gears are required, n D flip-fl...
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