Absolute maximum current of RevPi MIO

Makoto G · Post by **Makoto G** » 07 Nov 2022, 02:24

I'm going to use RevPi MIO to read the voltage of a sensor.
However, this sensor is low voltage, but high current.
I can expect currents in the range of 50 - 500mA, with the voltages ranging from 0.3 - 1V

I could not read the maximum current allowed for analog inputs of RevPi MIO from the data sheet.
Could you tell me if you know it?

Thanks in advance.

nicolaiB · Post by **nicolaiB** » 07 Nov 2022, 11:32

Hi Makoto,

what for a sensor do you want to use with the MIO? Do you have a datasheet?

Nicolai

Makoto G · Post by **Makoto G** » 07 Nov 2022, 16:04

Hi Nicolai,
Thank you for your reply.

We are investigating the output of an experimental bio-battery using microorganisms.
So it's not a sensor with a data sheet, it's a self-made one.
Normally, there is no problem because the output of the battery flows to a circuit whose impedance is much lower than the input impedance of the RevPi MIO.
However, there is a risk that the output of the battery will flow directly to the input of the MIO in the event of an accident such as a disconnection or misconnection of wiring.
The current output from the battery is estimated to be approximately 50 mA to 500 mA.

I would like to know the maximum current allowed by MIO as a reference for safety measures.

nicolaiB · Post by **nicolaiB** » 09 Nov 2022, 17:15

Do you have a schematic of your setup? In order to measure a current you need to use a resistor as a shunt (eg. 0,5 Ohm). With the MIO you can only measure a voltage. The voltage input is high-impedance (like a multimeter) and therefore the current does not really matter.

Nicolai

Makoto G · Post by **Makoto G** » 10 Nov 2022, 02:03

I'm sorry that I only have a simple schematic.
I only want to measure the voltage between the anode and cathode of the battery.
However, we need to change the resistor in the figure frequently, and I am worried that the battery output will be directly input to MIO by mistake.
The output of the battery will be around 1V, 500mA.
Do I need a fuse or something?

Thank you.

Post by **dirk** » 10 Feb 2023, 15:20

Hello Gwyneth, there is no problem while changing the battery if the cables at MIO stay where they are and the battery is changed, so it would be impossible to errornes contakt the wrong pin at the front connector. Inside there is a ESD protection and a transil diode

whoare365q · Post by **whoare365q** » 11 Apr 2023, 13:40

Normally, there is no problem because the output of the battery flows to a circuit whose impedance is much lower than the input impedance of the RevPi MIO.