Hi guys,
I'm working on an constant current led driver, in particular the TPS92512 from T.I.
It works but I have 2 problems: led is flickering and there's audible noise when PWM dimming.
I think that the problem is on the inductor, but I don't know how to solve it, I mean..do I have to pick
an inductor with higher DCR, higher Isat.. or what?
Thank you in advance
The datasheet shows that chip PWM input frequency must be in the range 100 to 1000Hz, which may
be the flicker issue - go for the higher end of this range. The noise from the inductor
will be down mainly to the PWM frequency I think (the switching frequency is ultrasonic). The inductor may
be mechanically resonating. Its a fact of life with high current switch mode supplies that the inductor
will vibrate due to magnetostriction. Whether that vibration is a problem depends on the frequency,
the mass of the inductor, whether the PCB has a mechanical resonance at that frequency and probably
many other factors.
If the inductor is also getting hot I'd suggest go for a larger inductor (same inductance, higher current rating)
as that might solve both issues.
Hi MarkT,
thank you dor your reply. I'll try to change the PWM frequency from 100 Hz to 1kHz and I'll let you
know! 
Thanks again
Hi MarkT,
so with a PWM @ 1kHz the flickering is no more visible, but there's PWM audible noise.
@ 100 Hz PWM there's flickering, but noise is less annoying, and @ 1kHz there's no flickering but noise
is quite annoying 
Do you think that changing the value of the inductor could solve the issue?
