Design Note DN05034/D
November 2013
The NCL30051LEDGEVB LED driver evaluation board provides PWM dimming capability via gating the resonant half bridge converter on and off at the PWM rate. Effective minimum duty factor is about 10% being limited by biasing considerations.
Some applications require wider range PWM dimming often extending to 1% or below. This design note presents a method to achieve PWM dimming from 100% down to less than 1% using an enhanced power control circuit. A series FET switch is introduced in the driver output to interrupt the LED current in response to the PWM control signal. This method allows the converter to maintain proper bias conditions needed to support dimming over an extremely wide dimming range.
Device details:
- Device: NCL30051 + NCS1002
- Application: LED Dimming
- Input Voltage: 90-305 Vac
- Output Power: 50 W
- Topology: CrM PFC + Resonant Half Bridge
- Isolation: Isolated
Download Design Note DN05034/D (108 Kb)
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PWM Control Schematic
