I2C on Single Supply Logic Level Converter

Other Miscellaneous
1

Hi,

Please can you help explain how I connect I2C across the Single Supply Logic Level Converter?

I’m trying to connect a 3.3V SparkFun LoRa Thing Plus - expLoRaBLE to a 5V analogue sensor connected to 2 ADCs.

The ADCs both have separate I2C addresses configured but neither are responding.

I’ve connected the following:

VIN:

3.3V - 3-5.5V

GND - GND

SDA - A1

SCL - A2

VOUT:

5V - 5V

GND - GND

SDA - B1

SCL - B2

Unfortunately, I’ve already soldered it up - doh… this was largely because the analogue sensor connects by ribbon wire which i couldn’t connect to a breadboard. Anyhow - I can’t test connection changes easily so hoping someone knows what to do!

Thanks,

Artis

Fritzing sketch below:

Sensor Sketch_bb.png
Sensor Sketch_bb.png2604×1257 437 KB

2

Unfortunately I2C doesn’t work on the Single Supply Logic Level Converter, but it will work on [BOB-12009 or [BOB-15439.

It has to do with the TXB0104 that’s on the board not being able to function when there are pullup resistors on the I2C bus. :-(](https://www.sparkfun.com/products/15439)](https://www.sparkfun.com/products/12009)

3

Thanks for the quick response TS-Chris - back to the workshop :roll:

Out of curiosity - does the boost converter (TPS61200) on the Single Supply Logic Level Converter normally get quite hot?

There’s not much load on the high side.

4

I’ve just spotted your SPX-17238 which looks ideal for my setup.

Presuming that would work for both power boost and I2C logic conversion?

Now to find a supplier in the UK…

5

I’ve not personally tried using this part but I wouldn’t think it should get hot.

How much current are the devices connected to the output pulling?

6

very low - 2 ADCs @ 150µA + sensor @2mA & decoupling power to the sensor with a 10nF +100 nF capacitors

not sure if having the I2C connected to it is doing anything.

it’s finger burning hot.

I’ll remove it from the board tomorrow and run some tests on it.

Trying to track down a Qwiic Boost to replace it but they seem very scarce.

Thanks for your help!