LMZ12002: EN voltage of LMZ12002

ibrahim Heddi

Part Number: LMZ12002

Hello,

About the enable pin of the DC-DC lMZ12002, in the "absolute maximum ratings" part the maximum voltage allowed is V_(EN MAX) = 7V but in another part of the datasheet it is described that is possible to leave pin enable floating for always-on operation, the problem that for this configuration the EN pin is internally pulled up to VIN. and for information, Vin is can be raised to 20 V exceeds V_(EN MAX). It's not contradictory?

over 3 years ago

0 Gerold Dhanabalan - Online Design Tools over 3 years ago

TI__Genius 14455 points

Hi Ibrahim,

Even though the EN pin is internally pulled up to VIN, there could be transistors in the path, essentially limiting the voltage on the EN pin from exceeding when you leave it floating. You externally cannot do that. You will need the resistor divider network as described in the datasheet.

Regards,

Gerold

0 ibrahim Heddi over 3 years ago in reply to Gerold Dhanabalan - Online Design Tools

Prodigy 30 points

Thank you Gerold Dhanabalan,

So, there is no problem to leave pin enable floating for always-on operation when Vin raised to 20 V exceeds V_(EN MAX) =7V?

0 Kris F over 3 years ago in reply to ibrahim Heddi

TI__Genius 17905 points

Hi Ibrahim,

Yes, there is no issue leaving EN pin floating when VIN is raised to 20V. To add to Gerold's response, the pull up to VIN is not a resistor. It is a current source from VIN to EN that is clamped internally to about 5V less a diode drop.

Kris

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LMZ12002: EN voltage of LMZ12002