I2C Logic Level Converter with Regulator Module

Description

The I2C Logic Level Converter with Regulator Module is designed to interface between 5V and 3.3V devices using the I2C bus.

PACKAGE INCLUDES:

• I2C Logic Level Converter with Regulator Module
•  1×4 right-angle male header strip (x2)
• 1×4 straight male header strip (x2)

KEY FEATURES OF LOGIC LEVEL CONVERTER 4-CH BI-DIRECTIONAL MODULE:

• 2 bi-directional channels can convert up to 2 logic signals, typically used for I2C
• Can convert between 3.3V and 5V logic circuits
• Utilizes N-Ch MOSFET transistors for level translation
• Includes on-board 3.3V regulator to power 3.3V logic
• Operates from 5V power

Unlike most logic level converters, this module includes a 3.3V 150mA regulator so the device can both level shift the I2C SDA and SCL logic lines using only 5V power as well as power a 3.3V peripheral without requiring a separate 3.3V supply as long as the current requirements are under about 100mA. This can be especially handy with some of the smaller 5V MCUs that do not have their own 3.3V regulator like the Pro Mini 5V/16MHz module or if the regulator doesn’t have enough current to handle the 3.3V load.  Some are only good for about 30mA.

The circuit makes use of N-Channel MOSFET transistors and some pull-up resistors to take care of the voltage translation.

Module Operation

The ‘A‘ side of the module is the 5V side while the ‘B‘ side of the module is the 3.3V side.

To use the module, you hook up the 5V power to the AVCC pin.  Unlike most logic level converters you do not hook up 3.3V to the BVCC side because the module has its own built-in 3.3V regulator.  You can however use the BVCC pin to provide power to a 3.3V peripheral.  The on-board regulator is rated for 150mA, but you should keep current draw down under about 100mA to avoid heating problems.

The 5V logic SCL line connects to the ASCL pin and and the 3.3V SCL line connects to the BSCL pin.

Similarly the 5V logic SDA line connects to the ASDA pin and the 3.3V SDA line connects to the BSDA pin.

There are two Ground pins on the board as well.  At least one should be connected to the 5V circuit.  The other ground can be used to provide a ground to the 3.3V peripheral if needed.

Module Connections

The board has the following pin connections:

• AVCC = 5V input
• BVCC = 3.3V output
• GND = Ground (x2).  At least one needs to connect to 5V ground.
• ASCL / BSCL  =  I2C Clock channel
• ASDA / BSDA  = I2C Data channel

The ‘A‘ side of the module is the 5V side while the ‘B‘ side of the module is the 3.3V side.

To use the module, you hook up the 5V power to the AVCC pin.  Unlike most logic level converters you do not hook up 3.3V to the BVCC side because the module has its own built-in 3.3V regulator.  You can however use the BVCC pin to provide power to a 3.3V peripheral.  The on-board regulator is rated for 150mA, but you should keep current draw down under about 100mA to avoid heating problems.

The 5V logic SCL line connects to the ASCL pin and and the 3.3V SCL line connects to the BSCL pin.

Similarly the 5V logic SDA line connects to the ASDA pin and the 3.3V SDA line connects to the BSDA pin.

There are two Ground pins on the board as well.  At least one should be connected to the 5V circuit.  The other ground can be used to provide a ground to the 3.3V peripheral if needed.

Module Assembly

The module normally ships with two right-angle male headers but we also toss in a couple of straight male headers for easier use with breadboards.  The pins are on 0.5” centers and work well in a solderless breadboard.

If soldering on the straight male headers, to ensure good alignment during soldering first insert the loose headers into a solderless breadboard.  The module can then be placed on top of the headers and easily soldered in place.  The headers can be be soldered to either the top or bottom of the board.

OUR EVALUATION RESULTS:

These modules work very well and are an easy way to implement level shifting.   Besides I2C, it can be used to level shift an other 2 signals as well as provide a source for 3.3V power.

The 10K pull-up resistors tend to be the limiting factor for the maximum switching speed that can be obtained with these modules depending on the capacitive load.  400KHz operation is usually possible.  If you are trying to push the speed boundaries and are seeing data glitches, lower value pull-up resistors can be used to speed up rise-times.

BEFORE THEY ARE SHIPPED, THESE MODULES ARE:

• Sample tested per incoming shipment
• Kitted with headers and repackaged in high quality resealable ESD bag for protection and easy storage

Notes: 

1. None

Technical Specifications