LM3433 minimum frequency on PWM pin

Himanshu Jain

Other Parts Discussed in Thread: TPS92515, TPS92513, LM3404

Would someone know the minimum frequency that can be used to drive the PWM pin on an LM3433 circuit.

I was trying to run it between 30-100 Hz and my circuits developed some snags. The output is now only 1A so most probably the Mosfets have konked off.

Has someone had similar issues?

Himanshu

over 9 years ago

JCHK over 9 years ago

TI__Guru 50090 points

Hi Himanshu,

The LM3433 was designed to work best with dimming frequencies above 30KHz! Normally customers prefer not dimming in the 30-100Hz range as this is perceived as flicker.

I am not sure what the minimum frequency is, but it is likely closer to 30KHz

Regards,

Himanshu Jain over 9 years ago in reply to JCHK

Prodigy 140 points

Thanks John

So if I am looking at a frequency range from 30-2000 Hz (max), should I use the Enable pin on LM3433? Can it take this frequency? Is there a mention of it on the LM3433 datasheet?

Clinton Jensen over 9 years ago in reply to Himanshu Jain

TI__Mastermind 25500 points

Does the circuit need to be common anode? If you are only driving 1A there are better choices if not such as the TPS92513 or the TPS92515. They can dim at those low frequencies quite easily. The LM3404 would be another good option.

Himanshu Jain over 9 years ago in reply to Clinton Jensen

Prodigy 140 points

I am driving it at 28A. Don't know of any other IC which can do that. Are there any? Have done quite a bit of testing as well on this board and am using it for another product as well

Best

Himanshu

Power management

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LM3433 minimum frequency on PWM pin