U3V70F12 enable pin and a uC

Support Voltage regulators
1

I want to use a U3V70F12 to power a small LED array, but I want to be able to switch it (the U3V70F12) on and off via the enable pin using a raspberry pi zero. Since my input to the U3V70F12 will be anywhere from 5 to 11v, I cannot just connect ENABLE to a 3.3v pi zero GPIO pin since ENABLE is pulled up to VIN by a 100k resistor.

How can I drive the enable pin low via a gpio pin from the pi zero? I don’t want to use a mechanical relay since this project is very sound sensitive and I want to avoid the “clack” of the relay.

Should I be looking at an SSR? I don’t think I could use a transistor to accomplish this, but obviously I could be completely wrong in that assumption! If I were to remove the 100k pull-up, would 3.3v from a pi zero to ENABLE be enough to turn on the regulator?

Any guidance would be greatly appreciated!

2

Hi.

You could definitely use a transistor to control the EN of the regulator. You could look at the power connections page of our A-Star Robot Controller LV schematic for an example. You could alternatively remove the on-board pull-up resistor and connect EN directly to your GPIO pin, which would leave the 800k pull-down in the chip. 3.3V should be enough to enable the regulator. Here is a picture showing where the pull-up resistor is.

reg21a_en_res
reg21a_en_res1200×338 106 KB

-Claire

3

Great! Thank you Claire!