Other Parts Discussed in Thread: TPS92692, TPS92691
Hi team,
LM3409 is buck topology... If Vin =9V, and Vout need to drive 3 LEDs (nearly 10V)...
does it works? or whether it has high risk?
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Hello Amelie,
Generally if the output and input voltage can cross (be higher an lower) you want to look at a buck-boost, boost to battery (it is also a buck boost) or a SEPIC. Depending on output current you could look at the TPS92691, TPS92692 and possibly other parts depending on LED current.
What will happen with the LM3409, the MOSFET will turn on and if it cannot hit peak current limit it will stay on. It will work but it cannot provide higher than 9V - Vcs to the output. Since LEDs have dynamic impedance they, most likely, will light up but not at full current. It will not damage the part, it is meant to operate this way.
Best Regards,