Duinotehc Logic level converter how does it's work ?

Using Arduino General Electronics
1

Hello,

I use a 5v microcontroller and i have some 3.3 V sensor so i bought a Duinotech 5V-3.3V logic level converter (DataSheet here ) but the datasheet is not enough for my level of understanding to use it,Does anyone know how to use this component ?

All the best

Vincent

XC4486-dataSheetMain.pdf (580 KB)

2

https://learn.sparkfun.com/tutorials/using-the-logic-level-converter

3

Tutorial is rather good.

That datasheet is misleading - it suggests this particular module includes a regulator to produce your 3.3 V from the 5 V, which it does not, however another common module actually does.

Also, the one-way "logic level converters" consisting merely of two resistors are going to be slower than the FET based bidirectional ones and quite unsuitable for use on I2C lines.

4

Thanks a lot ! I don't know if it's not out of my leage but i like to understand the difference between a Voltage divider ( that i was thinking to do ) and the two way Voltage logic converter ( i saw the internal schematic integrate a MOFSET but i look at it and i still don't understand what it's for).

Vincent

5

This will explain things if you can follow it.

an97055 I2C level shifting.pdf (75.3 KB)

6

Mike, I think that might be over his head.

@OP,
Try Googling these:

Voltage divider
logic level converter

7

OK try this.
Voltage divider only cuts down the voltage and so works only to convert high voltage to low voltage. That is only one way.

Using FETs or Transistors they act as amplifiers that can boost up the signal by amplifying it with a positive gain or cut down the signal by having a negative gain.

8

Posting here since its about the Duinotech Level Converter product and its somewhat relevant.

Just wondering if anyone else here has had issues with this product which appears to be a known design flaw (in addition to Pauls comments above) that puts the product out of spec.

I found this out while testing the Duinotech Logic Converter unit, and it seems that the 'Rx' lines incorrectly drop the level to 2.5V instead of 3.3V.

This unit appears to be the same unit that SparkFun used to sell before discontinuing the product due to the product 'board not stepping down from 5V to 3.3V correctly'.

In the comments on that SparkFun Page there is a top comment posted over 8 years ago:

"The resistors to generate a 3.3v output low side should be 10k R1 and ~20k R2. As is, the two 10k resistors split the voltage 50% resulting in approx 2.5v low side. This is outside the acceptable window for many 3.3v part like the LIS302DL sold on this site."

Kudos to Sparkfun for revising the product and putting out a new version. But if this was discovered over 8 years ago, why are Jaycar trying to sell this product (rebranded with their own 'Duinotech' brand) which is known not to drop the levels correctly?

Would be good to see if anyone else has had the same issue and can confirm what is happening here.

9

But if this was discovered over 8 years ago, why are Jaycar trying to sell this product (rebranded with their own 'Duinotech' brand) which is known not to drop the levels correctly?

Because they bought up the back stock of the defective product for next to nothing and are trying to make some money? Just a thought.