3.3 to 5V and 5v to 3.3 Breakout: Sparkfun Logic Level Converter

The new Sparkfun Logic Level Converter

.from: http://www.sparkfun.com/products/8745

This one is very cool and work well between my XBee and my PIC18F.

Description: If you've ever tried to connect a 3.3V device to a 5V system, you know what a challenge it can be. The SparkFun logic level converter is a small device that safely steps down 5V signals to 3.3V and steps up 3.3V to 5V. This level converter also works with 2.8V and 1.8V devices. Each level converter has the capability of converting 4 pins on the high side to 4 pins on the low side. Two inputs and two outputs are provided for each side.

Bread board friendly! Can be used with normal serial, I2C, SPI, and any other digital signal. Does not work with an analog signal.

The level converter is very easy to use. The board needs to be powered from the two voltages sources, the high voltage and low voltage, that your system is using. High voltage (5V for example) to the 'HV' pin, low voltage (2.8V for example) to 'LV', and ground from the system to the 'GND' pin.

All the pins are labeled as INs and OUTs. These are relative to the board. A digital one going into the RXI pin on the 5V side will show up on the RXO pin on the 3.3V side as 3.3V. A digital one going into the TXI pin on the 3.3V side will show up on the TXO pin on the 5V side as 5V.

Dimensions: 0.5x0.6"

Documents: Schematic

Enjoy that.

3.3v to 5v converter (Episode 2/5)

Conversion between the 3.3v to 5v logic signal.

.from: http://www.edaboard.com/thread11539.html

Hot to do an 5V signal will be level-shift to 3.3V and the 3.3V signal will pass-thru directly without attentuation.

Solution 1:

My simple method is to use serial resistor divider (few kilos, ie. 10kR) and diode (Schottky diode) to +3.3V (A - resistor, K - +3.3V).

Solution 2:

look 74LVC series chips, that's also available in very small one gate package ( and it is very low cost, for example the Philips 74LVC1G125GW or Texas Instruments SN74LVC1G125DCKR chips in small 5 pim SC-70-5 packege, low unit cost

Solution 3:

Take a look at www.chipcon.com in Application Note AN021. Texas Instruments has a similar good  PDF appnote also.

5v to 3.3v - Convert 5 Volts TTL signal to the 3.3 Volts CMOS interface 1/5

How to Convert 5 Volts TTL signal to the 3.3 Volts CMOS interface

.from: http://forum.allaboutcircuits.com/showthread.php?t=17057

I have a microcontroller working on 5V, which is directly connected to a sensor working on 3.3v for data communication. Can somebody give an idea about how to connect a mixed 3.3v and 5V different systems? Is there any IC available for level shifting from 5V to 3.3V? 

Solution 1:

http://www.national.com/mpf/LM/LM2937-3.3.html

Solution 2:

You can use the BC547 but you can use also a buffer or NOT gate with open collector output.