I'm building buck converter to drive led lamps. It consists of microcontroller, PWM generator, buck-circuit and current sensor. Microcontroller knows what target current should be and sets duty cycle basing on current sensor results.
The circuit, powered with +48V at VIN should drive led lamps with wide voltage and current ratings. Current limit is set in uC, independently for each lamp. Output must be filtered for as-low-as-possible ripple, because lamps are pretty far from the driver and I want to reduce EMI.
First simulation: 30kHZ PWM Frequency, 50% duty cycle, 1mH inductor, 47uF capacitor. With this circuit I want to drive 2.5A led strip.
However, in simulation, I can see very high overshoot current during first 2ms of operation. After that current is pretty stable.
I can't just put passive limiter there, because I have to retain ability to set output current.
Now, my questions:
- Will such current raise (3.6A for 2ms) destroy 2.5A rated led strip?
- How can I prevent such effect?
- What can I do to achieve better filtering of output current?
- Is there any way to reduce inductor size? With 100uH I get lots of ringing on drain
- How can I improve the circuit?