Logic level 5v => 3.3v converter

Other Miscellaneous
1

Hi. We need to connect an Arduino Mega PWM signal pin to a linear actuator-type device that only accepts 3.3v signal. Its power supply will be run off separate 12v system.

So basically there is no 2nd power supply for the Low-side voltage/grnd. Is that OK?

Here’s our plan:

*High side voltage & ground to 5v out & ground on Arduino

*3.3v signal wire from device to Low-side channel on converter

*5v Arduino PWM pin to High-side channel on converter

*Device power/ground to separate 12v system

*Low-side voltage/ground on converter gets connected to ??? nothing?

There are no schematic samples or documentation showing this kind of setup. Does Low-side voltage/ground have to be connected to something? If so, to what? Our device doesn’t have a power supply (it consumes power from a separate 12v system).

Would we be better off just soldering resistors? I already ordered this part though…

Thanks in advance!

https://www.sparkfun.com/products/12009

2

I would say it’d be easier to just solder resistors, but while we’re here…

I think that setup might work, and while I’m not certain if the low-side GND needs connection (if the high side has one, that is…this guide make me think it’s not needed https://learn.sparkfun.com/tutorials/bi … okup-guide) but worst-case, you could also tie this one to the GND from the arduino

3

The schematics for the level shifter can be found at http://cdn.sparkfun.com/datasheets/Brea … tional.pdf

GND is the same on both sides, so you can connect only one, but both power supplies need to have a common ground.

The low voltage side needs to be powered by 3.3v in your case.

As mentioned, for this application, a simple resistive divider made up of two resistors is the easiest and best choice.

/mike

4

Thanks guys for your replies. I appreciate it. Went ahead and tested the voltage divider/resistor solution by soldering in some 470 & 1k resistors for a calculated voltage of 3.4v - close enough. This config works, device ran smoothly. :smiley: Ordered some 910 resistors to use in production, to get 3.3v.