Powering SKU: U111 NB-IoT Unit
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Hello,
Your SKU: U111 NB-IoT Unit is specified to have 5V input. I guess that is for both power and io pins.I try to operate this device by feeding with 3V. (both power and io pins). This seems to work just fine.
Is it ok to power this device with 3V ? or should this be avoided ?
Best regards
HÃ¥vard -
Hello @haavard-holm
most (if not all) units have a 5 V input. Internally there often is a power regulator to 3.3 V or whatever voltage the ICs used in the unit requires. The signal lines are 3.3 V as they are connected directly to GPIOs of the ESP32 which is 3.3 V too. If the data lines of the IC in the unit have an even lower voltage level shifters are put in place.
The input voltage of the regulator is 2.7 V to 5.5 V. The minimal voltage drop between input and output is about 0.6 V for these regulators. So if you feed it with 3.3 V I'd guess the output voltage to be about 2.7 V.
According to its datasheet the SIM7020 IC has an operating voltage range from 2.1 V to 3.6V so you should be fine. Its data lines are 1.8 V which are then level shifted to the output voltage of the regulator (e.g. 2.7 V) which should still be high enough for the ESP32 GPIOs to recognize properly.
Thanks
Felix
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