LM3405 minimum duty of PWM dimming

Expert 3040 points

Other Parts Discussed in Thread: LM3405

HI Team,

I would like to know the minimum duty of PWM dimming of LM3405.

I could find graph of average LED current vs Duty Cycle of PWM Dimming sigal at EN/DIM pin.

I think the graph plots down to about 5%? likely, is this the minimum duty?

my customer want to use 500mA as full brightness but want to dim down to about 100mA. is this possible?

Best Regards,

over 8 years ago

0 Clinton Jensen over 8 years ago

TI__Mastermind 25500 points

How low the minimum pulse width can be depends on the external components and the operating point, then the minimum duty cycle depends on the PWM frequency used. But as you can tell from the graph 500mA maximum and 100mA minimum should be fairly easy depending on PWM frequency. You can also dim below the 5% shown in the graph, it will just be non-linear since the LED current will never reach the full value during the on time.

0 NY over 8 years ago in reply to Clinton Jensen

TI__Expert 3040 points

I understand well. Thank you

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LM3405 minimum duty of PWM dimming