LED flicker problem

Publié le par er86

User question: when lower voltage drives the halogen lamp, halogen lamp brightness is reduced, no other changes. The drive LED reduced voltage, LED Lighting module LED in a certain extent the occurrence of flicker. Why?


Expert reply: halogen lamp is purely resistive load, therefore the halogen lamp electronic transformer is matched with the good work. While the LED lamp is a capacitive impedance and inductive impedance load, halogen lamp electronic transformer to accept the LED lamp load when its output capacity will be greatly reduced, as the output voltage from12V drop to7V, such as8V driver started IC enter the under-voltage protection state, the halogen lamp electronic transformer output voltage to12V so, go round and begin again, make you see LED lights flashing. The solution is to choose to use the starting voltage is lower than 6V driver IC.


Underwater lights should be how to design?


User question: underwater lights should be how to design? What problem should note? LED beads by impact current caused by blast is it right?? how to solve?


Expert reply: from a security perspective, underwater lamps require the use of low-voltage isolation power supply, as far as possible the use of international common AC36V power, so AC24V, AC12V is the optional power supply standard.


Long distance will cause a voltage drop, can increase the wire diameter to compensate. In addition, AC online transmission ratio DC online transmission loss to small.


Underwater lights are based on AC24V safety power supply, therefore can choose Vin = 6-30V, Iout =1.2A, PT4115system application parts seldom do drive power, it uses a four Schottky diode as bridge rectifier,Bluetooth keyboard device a filtering storage capacitor, an output current setting resistance, a freewheeling Schottky diode and a continuous current inductor.


Power system load instantaneous mutations can cause current surge, in the circuit with protection device to effectively inhibit. Early 9910IC has" fried beads" problem, need to improve the application circuit.

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