Hi.
I am designing a LED driver module based on LM3406HV. I have used online tool for calculation of circuit parameters and, based on the obtained results, I tested the circuit on a breadboard and then manufactured prototypes.
The circuit I am using is shown below:
BOM:
I am using PWM dimming. Scope screenshots are shown below:
PWM pulse duration
PWM period (repetition rate)
The driver displays unstable behavior when dimming.
The following screenshots are taken with a scope probe attached to point A (marked with an arrow in the circuit diagram above), using the 1:10 divider on ch. Y
- Stable work of the circuit
2. Unstable operation mode
I request your help in understanding the problem. Can you please explain what is happening? What am I doing wrong?