5V to 3.3V level converter.

[skyscraper]

It often comes up that you need to convert a logic output from 5V to 3.3 V. One simple way to do this is to connect the 5V output to the anode of a red LED, then connect the cathode to ground via a resistor of from 500 ohms to 10 K ohms. Take the 3.3V output off the cathode. Output voltage will be in region of 3 volts. The lower value resistors cause the output to drop slightly more than the higher values, but not much. Red LED glows when output is high of course!

regards
Andy

[Rob Thomson]

Thanks for the post. Useful info.

Just thinking - for those new to electronics, a picture often does wonders



Sent from my GT-I9300 using Tapatalk

[skyscraper]

Thanks for the post. Useful info.

Just thinking - for those new to electronics, a picture often does wonders

OK. I can take a hint


regards
Andy

[DaSpider]

I wonder why do you think you need the resistor. A red led has a fix voltage drop of 1.8-2.2V, depending on the led. The resistor adds extra impedance to the input, which is known to cause distortions in square waves in high frequencies.

[Kilrah]

Because the LED will only drop voltage if current is flowing through it. Given the 3.3V side input this would be connected to typically has very high impedance no current would flow and the level wouldn't be clearly defined.

[kaos]

Woo, I can use that to connect the 5V promini each output to 3.3V module in multiprotocol module and have a sparkling flashing leds then?

hehe, only Geeks can figure this out.