3.3v devices

stef

Hi

I want to do a project with a device (xport from lantronix) that has a 3.3V power . The high of an output is then of course also max 3.3V.(normal high is 2.4V)·Is that possible to directly connect it to an SX48 or do I need to adjust the high voltage in some way. If not neccesary I won't do it to spare some parts. If neccesary, how is the easiast way to do that. (xport is a tcp/ip to serial device. I want to use a bauterate of 9600. so any adjustmend on the line's need to be able to follow that speed).

Any sugestions?

Stef
·

Velocit

So... you need the xport to serve as an input to the SX48, or does the SX48 need to serve as an input to the xport? If you need to limit the standard +5V high signal from an SX48 a simple voltage divider circuit would do the trick. Given that these are IC to IC signals, you shouldn't have to worry about loading effects, etc.. Conversely, if you need to trigger a logic high on the SX48, you don't need to do anything. TTL threshold is about 1.4V, so anything above that counts as high; even with CMOS level thresholds you'll be fine.

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-Paul

stef

Thanks paul

I'm going to give it a try. I'l connect him direkt to the sx48( the imput with a pull up 10K and the output direkt connected).

stef

Phil Pilgrim (PhiPi)

You can also power the SX48 with 3.3V instead of 5V, don't forget; and it will run cooler that way. Just be sure to set the brownout voltage low enough that it doesn't stay in reset.

-Phil

stef

Thanks Phil

I'l try that one also.



stef

dkemppai

Don't forget, If you use 3.3 Volts be sure that the key is powered with 5 volt power power. The key can't run at 3.3 Volts.

Also, when working with a·SX running at 3.3V, ALWAYS remove the key from the target device before shutting off power to the key.

Trust me on this...

-Dan


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"A saint-like quantity of patience is a help, if this is unavailable, a salty vocabulary works nearly as well." - A. S. Weaver

Post Edited (dkemppai) : 4/16/2008 1:27:32 AM GMT

JDOhio

SparkFun has a great tutorial on this topic. Check it out:
http://www.sparkfun.com/commerce/present.php?p=Sensor-Interfacing

Joe