LMZ12002 enable pull-down resistor

Luis Juarez

Other Parts Discussed in Thread: LMZ12002

Hello,

I'm going to use a LMZ12002 IC with my project, and I have a question about this IC.

I need to enable/disable the IC controlling the EN pin with an Arduino (0v - 5v).

But when the arduino is put on sleeping mode, the Arduino port connected to the EN pin becomes floating, and this could result in the LMZ12002 enabled while the arduino sleeping.

To avoid this I'm going to use a 100k pull-down resistor between the EN pin and ground.

But the datasheet of the LMZ12002 says that the EN pin is internally pulled-up (and if you leave the pin unconnected the IC is enabled).

Is it possible to use a pull-down resistor in the EN pin of the LMZ12002? If yes, what would be a good resistor's value to minimize losses?

Regards,

Luis.

over 10 years ago

0 Greenja over 10 years ago

Guru 22270 points

Hello Luis,

Welcome to the Forum!

On page 13 of the Datasheet there is a section for Enable Divider. It allows you to set a voltage level that will disable the device. You can try using this design so to see if it works with your floating output.

Thanks,

0 Marc Davis-Marsh over 10 years ago

TI__Genius 10095 points

The pull up current on the enable pin is around 6uA. To keep the voltage below say 1V and keep the part disabled would require a pull down resistor < 1V/6uA ~ 166kOhms. However if you want to give yourself more margin the datasheet shows 12kOhms which would be well away from the enable threshold of the device.

Regards,

Marc

0 Luis Juarez over 10 years ago in reply to Marc Davis-Marsh

Prodigy 20 points

Thank you!

Regards,

Luis.

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LMZ12002 enable pull-down resistor