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Maximum current on inputs - Panda II


#1

I have searched and I did not find anything - or I am just not correctly understanding what I am reading.

What is the maximum safe current to the inputs on a Panda II? Both analog and digital would be appreciated. I am wanting to attach a circuit to an input so I can detect when a portion of that circuit is powered, but I don’t want to fry my Panda II. The Panda II and the monitored circuit are both on the same power supply so I don’t have any concerns about voltage (both are at a well regulated 5v). I am assuming I will need to use a current limiting diode, but I don’t know what current I need to limit to.


#2

You do not need to be concerned with current on an input. Voltage has to be controlled.

Digital input are nominally 3.3V but the Panda II can handle up to 5V.

Analog input are a maximum of 3.3V.


#3

The problem is not how much current a pin can sink - that will typically be very small. The problem is always trying to source more current than the pin is capable of. You could for instance tie a pin to 5v directly and the chip will only source a low current on input, its internal circuitry will limit what it draws.

When you want to put in a current limiting resistor, you really just need to consider how much current you want to limit that part of your circuit to - usually to minimise the (unnecessary) power consumption.

For analog input, you don’t want to add CL resistors, as they’ll influence your ADC reading


#4

Thanks for the feedback.