I've been scouring the Manuals, Datasheets, Forum, Google, and Wikipedia to try to find the maximum DC input voltage for a 14M2 PicAXE chip. I'm talking about a digital input signal, not the supply voltage. I will be using a 5V voltage regulator for the supply.
But my input signal for triggering my PicAXE program is going to be 32VAC. I will have this going through a Bridge Rectifier and filtered with a 10uF capacitor to smooth it out. (The reason I'm using such a small cap is because it won't be driving any current, it will only be used for the input pin as a digital 1. My circuit supply voltage will be coming from a different source.).
After rectifying and filtering the voltage, it will be about 45VDC. My question is how far do I have to drop this down using a voltage divider before it gets to the input of the PicAXE? Do I have to drop it all the way down to 5V? Or can the PicAXE handle a higher input voltage?
The only documentation I have found concerning this issue is on Wikipedia where it says:
I can use an 82K resistor and a 12K resistor to divide the voltage down to 5V, but I thought that if I could just use one resistor in series with the input pin as Wikipedia says, I could save some space as I am using a fairly small board and space is an issue.
But regardless of my circuit, it still would be nice to know the maximum input voltage of a PicAXE chip.
Thanks.
But my input signal for triggering my PicAXE program is going to be 32VAC. I will have this going through a Bridge Rectifier and filtered with a 10uF capacitor to smooth it out. (The reason I'm using such a small cap is because it won't be driving any current, it will only be used for the input pin as a digital 1. My circuit supply voltage will be coming from a different source.).
After rectifying and filtering the voltage, it will be about 45VDC. My question is how far do I have to drop this down using a voltage divider before it gets to the input of the PicAXE? Do I have to drop it all the way down to 5V? Or can the PicAXE handle a higher input voltage?
The only documentation I have found concerning this issue is on Wikipedia where it says:
However, it doesn't define "High Voltage Signals".Most Digital Inputs are protected by diode clamps to the power rails, which as well as offering good ESD protection, allows interfacing to high voltage signals often with little more than a current limiting resistor being required.
I can use an 82K resistor and a 12K resistor to divide the voltage down to 5V, but I thought that if I could just use one resistor in series with the input pin as Wikipedia says, I could save some space as I am using a fairly small board and space is an issue.
But regardless of my circuit, it still would be nice to know the maximum input voltage of a PicAXE chip.
Thanks.