What is a capacitive buck LED driver?
|Using a voltage source connected to the LED in series with a resistor is the easiest way to get the LED to work. When designing an LED driver, you need to know the current and voltage characteristics of the LED. Due to the different specifications of LED manufacturers and LEDs, their current and voltage characteristics are different.|
Nowadays, LED lamp products produced by many manufacturers use the resistor-capacitor step-down mode, and then a Zener diode regulator is used to supply power to the LED. This method of driving LEDs has great drawbacks. Firstly, it is inefficient, consumes a large amount of electric energy on the step-down resistor, and may even exceed the power consumed by the LED, and cannot provide a large current drive, because the larger the current, the more The more power is applied to the buck resistor, so the LEDs in many products are not connected in parallel, but in series to reduce the current. Secondly, the ability to stabilize the voltage is extremely poor, and there is no guarantee that the current through the LED will not exceed its normal operating requirements. The design can be powered by reducing the voltage across the LED, but this is at the expense of reducing the brightness of the LED. When the LED is driven by the RC mode, the brightness of the LED cannot be stabilized. When the power supply voltage is low, the brightness of the LED becomes dark: when the power supply voltage is high, the brightness of the LED becomes bright. The biggest advantage of driving LEDs in a RC mode is low cost.
Capacitor step-down circuit belongs to a common small current power circuit. Because of its small size, low cost and relatively constant current, it is often used in LED drive circuits.