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Maximum voltages on SX127X IO pins

Semtech Transceivers SX127x family
#1

The SX127X devices have a maximum stated supply voltge of 3.9V.

But there is no maximum voltage given for the IO pins, SCK, MOSI, MISO etc.

There does seem to be an assumption by some users of the devices that the IO pins are 5V tolerant, but I cannot find a reference to this in the datasheet.

So what is the maximum allowed voltage on the SX127X IO pins ?

#2

Hi,

Absolute maximum VDD I/O for the S127x family is also 3.9V, the chip is not 5V tolerant

1 Like
#3

Thanks for the reply.

Did you mean ā€œthe chip not 5V tolerantā€

#4

Right, sorry :slight_smile: I updated my answer

#5

Thanks again for the reply.

If you anyone is daft enough to connect a LoRa device (RFM9x for instance) to a 5V processor (Arduino UNO for instance) the 5V outputs from the processor will raise the LoRa device VCC to circa 4.2V via phantom powering from the IO pins, which does exceed the absolute max 3.9V VCC allowed.