View Full Version : 5v-3.3v Logic Level Converter

04-13-2012, 12:44 AM
Hi I am working on a GPS tracker which uses Arduino Uno - Atmega328 and SIM300 module.

The operating voltage of Arduino is 5v and SIM300 is 3.3v.

Is there any simple diy circuit which can be used for the logic level conversion?

Ready made boards like http://www.sparkfun.com/products/8745 are available but out of stock at many Indian online stores.

I know we can redo the same thing, Can some one please post some circuits or links related?


04-13-2012, 02:46 AM
Which sim300 board do you have ? sim300 in itself is very hard to solder , usually the breakout boards have what you are looking for.

04-13-2012, 03:22 AM
Hi Vikas,

I am using SIM300 module with breakout board manufactured by http://www.sife.in/

It has RS232 Serial interface and am able to test it, by connecting to Computer's serial port. For the GPS tracker it I need the Arduino to be able to communicate with the SIM300 for GPS coordinate transmission.


04-13-2012, 02:51 PM
check what voltage is the internal board running at , SIM300 is not a 3.3V part . It runs aroun 4.1V .

04-13-2012, 05:14 PM
Hi Vikas, you are right. SIM300 RX reads a 4.1V and TX reads a 2.9V on multimeter. So is there any diy circuit to handle this logic level conversion between SIM300 and Atmega328?

04-19-2012, 12:15 AM
If so, for UART, simple resistor dividers will do the job....

04-23-2012, 04:45 PM
why not use max3232

08-21-2012, 02:46 AM

I can recommend 2 solutions and both works 100%:

1) ISO2771 from texas Instruments (there is also ISO2770 so read datasheet to saw difference)

2) And another beautifull componente same from TI that I found recently, it is TXS0108E (there is also 2-channel chip)

05-15-2013, 12:51 PM

06-17-2013, 01:36 PM
You can use CD4050B or HCF4050 but those are single direction level shifters. So u need to have dedicated input and output pins.