Voltage to pressure and temperature sensors


Can I connect the Bar100 and Celcius fast response-sensors directly to the 3.3V pin on an Arduino Uno or a Feather M0 Adalogger?

On the Bar100 product page it says “It operates on 3.3V I2C voltage but can accept power input up to 5.5V”, so I figured 3.3V would be great. But then I came across the “Guides” part on the I2C Level Converter product page where it states “most I2 devices are 3.3v, but the Bar30 and Celsius operate best with 5v power”. This made me confused, and I figured it best to ask to avoid potentially ruining the sensors.

Hi @Jacobsen, welcome to the forum :slight_smile:

Our pressure and temperature sensors are still expected to be able to run with lower supply voltages, but they include a voltage regulator to enable powering with up to 5.5V, and since power regulation is generally not 100% efficient it’s best to use a voltage supply above the regulator’s output voltage (in this case 3.3V) if possible to avoid larger current draws.

It should be ok to use a 3.3V supply voltage (or even as low as 2.5V for some of the sensors), you just need to make sure the supply is stable, and has sufficient output capacity to power the sensor :slight_smile:

Under-powering a sensor is unlikely to damage - instead it may fail to communicate properly, or could provide inaccurate measurements.

Hi @EliotBR , and thank you for clarifying! Is one of the reasons for using the level converter to ensure a stable supply voltage then, since it also only provides 3.3V? (I’m sorry if my questions are naïve - I’m still very new to all things electronic…)

Our I2C Level Converter actually allows selecting which supply voltage to provide:

More generally though, the level converter’s purpose is more about the signal voltage than the supply voltage - the power pass-through is a convenience feature we’ve chosen to include on ours.

5V devices like an Arduino are quite common in the hobbyist / DIY electronics space, but a device running on 3.3V may be damaged by receiving 5V signals on its communication pins, and depending on its measurement tolerances a 5V device may not register 3.3V signals as valid communication. The level converter acts as the bridge between the devices, allowing 5V signals on one side to communicate with 3.3V on the other :slight_smile:

Ah ok, I think I understand now. Thank you so much for taking the time to explain!

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