SparkFun Forums

[woolyloach]

https://www.sparkfun.com/products/526

Would this be suitable for converting a 0-5V line to 0-3V?

Not a EE and my hardware guy is out sick.. sorry clueless programmer here..

[Mee_n_Mac]

https://www.sparkfun.com/products/526

Would this be suitable for converting a 0-5V line to 0-3V?

I'm not sure what you mean by 0-5v and 0-3v, but it will make a 3.3v output given a 5v input so long as you don't draw more than 800 mA from that output. If you plan on drawing more than 300 mA you should also plan on adding a heatsink to it.
https://www.sparkfun.com/products/121

[woolyloach]

https://www.sparkfun.com/products/526

Would this be suitable for converting a 0-5V line to 0-3V?

I'm not sure what you mean by 0-5v and 0-3v, but it will make a 3.3v output given a 5v input so long as you don't draw more than 800 mA from that output. If you plan on drawing more than 300 mA you should also plan on adding a heatsink to it.
https://www.sparkfun.com/products/121

I have a brushless DC motor being driven by a TI DRV8301 chip. The Hall sensors output 0-5V, but they feed into the GPIOs of a TI MSP430 and anything over 4.2V will blow out the entire port (!!). I'm trying to find a way in which I can make sure nothing over 3.3V goes into those GPIOs.

I suspect this will work, I'm going to order a few and just experiment. From what you say, this should work fine for the task.. I only care if the voltage hits over 3V (to trigger the interrupt).

Thanks for the response!

..ed..

[Mee_n_Mac]

I have a brushless DC motor being driven by a TI DRV8301 chip. The Hall sensors output 0-5V, but they feed into the GPIOs of a TI MSP430 and anything over 4.2V will blow out the entire port (!!). I'm trying to find a way in which I can make sure nothing over 3.3V goes into those GPIOs.

Well that's a wholly different thing ! You don't want a voltage regulator (it won't work, responds too slowly), you want a limiter. For that matter a simple voltage divider is good enough. Can you provide a link to the Hall sensors used so I can make a good recommendation ?

Meanwhile ...
https://learn.sparkfun.com/tutorials/voltage-dividers

https://learn.sparkfun.com/tutorials/diodes (scroll to bottom re: Zener diodes)

[woolyloach]

Urgh, the sensors are built into the motor and the spec sheet doesn't call out their part numbers.

The EE was trying to make some gimmick with resistors before he threw his back out with two slipped disks, so he's not really able to help much. I'm having to take over some of his work and I'm a software guy.. brain hurts..

All I know is that 5V goes in, and I get 0-5V coming out to me...

Let me go read those tutorials and see if I can contact the motor vendor for the Hall sensor info.

[Dave Mueller]

A Zener diode will clamp everything below it's limit, that offers over voltage protection, but it sounds like you really need to convert a signal that varies from 0 to 5 V, to a signal 0 to 3.3 V. Use a voltage divider with a 2:1 ratio, i.e. 10 K and 5 K resistors. Wire them in series 5 V > 10 K > 5 K > ground. The junction of the two resistors is your 3.3 V tap point. Put a 5 V Zener across both resistors for some over voltage protection.

This will work if the Hall sensors are sending a varying voltage based on position and if it's just 0 or 5 V.

[n1ist]

Just to clarify Dave's post. The resistor divider connects to the 0-5V output of the hall sensor, not to the 5V rail itself.
/mike

[woolyloach]

Thanks a TON for all the help! I read through the tutorials and now feel less clueless.

I have the Sparkfun resistor pack so I'm good to go there, just need to free up room on the breadboard.

Have a great weekend!