Tool/software:
In my design, my LM 5155 is connected to a regulated 24V regulated supply. The load is an LED that needs 28~37 V, with less than 1 A of current. I need to control the brightness of the LED with a reference command voltage that is generated through a 12 bit DAC, which is connected to a separate regulated 5V LDO supply unrelated to the LM5155.
I have a 1.2 ohm resistor in series with the LED to derive a voltage referenced to the load current, that I then compare with the command voltage as part of the feedback loop, which then drives the FB pin. Everything works fine, and I can change the LED brightness with the command voltage. However, at low LED load currents, the LED flickers ever so slightly (picked up by a camera in my application), as my feedback loop goes into oscillation.
Can I get rid of my feedback loop and associated oscillation, and simply drive the FB pin with the command voltage? I realize there will be loss of load regulation, but since my load is steady (just the LED), I can live with a voltage controlled switched supply which I can increase/decrease to get the desired LED brightness.
Please do let me know. Thank you!!
