12/24V to 5V level translator

Alvaro Aguilar1

Hello,

I am working on a project that will be powered by car/truck batteries. I need to measure the RPM from the motor, and I believe the signal will come as a 12 or 24V pulse (depending on the type of battery used).

I don't know how to proceed: should an opto-isolator be used, or are there level translators that can convert such high voltages to 5V logic?

Thanks,

Alvaro

over 14 years ago

0 Hattie over 14 years ago

TI__Genius 9085 points

Hi Alvaro,

12V is outside of our standard translation range. You may want to look at an isolator. I'm going to move this post to the isolation forum, hopefully the can help us there!

0 Thomas Kugelstadt over 14 years ago in reply to Hattie

TI__Mastermind 28265 points

Alvaro,

isolated level shifting is easier accomlished with optp-couplers. Our digital isolators are designed for 5V to 3V supply systems only. With an opto-coupler you can match the series resistor to the input LED to the 12V supply. In the opposite direction, if you need the low-volt side to control any actuators on the 12V side, there are many opto-coupler with open drain or open-collector outputs which again allow you to match the collector resistor to the 12V supply.

Regards, Thomas

0 Thomas Kugelstadt over 14 years ago in reply to Thomas Kugelstadt

TI__Mastermind 28265 points

Hi Alvaro

I thought perhaps you don't need to level-shift when you use a sensor that does it for you. Anyway searching the Internet for "RPM measurment schematic" I found an interesting link. Perhaps that might be a solution you're intersted in:

http://www.mcselec.com/index.php?option=com_content&task=view&id=106&Itemid=57

Regards, Thomas

0 Alvaro Aguilar1 over 14 years ago in reply to Thomas Kugelstadt

Intellectual 705 points

Hi Thomas,

Thanks a lot for the valuable information! This sensor might be a life-saver for our application.

Have a nice day,

Alvaro

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12/24V to 5V level translator