safest way to convert tension

[dxtr]

Hey everyone
i need to convert ( 0v-->90V) to (0v ---> 5V) so i can use it in my Micro-controller , i tought about using tension devider but i don't think its a good idea because of joule heating
can you please help me with this ?

 

[crutschow]

Typically you use a DC-DC switching regulator for that purpose.

 

[dxtr]

Typically you use a DC-DC switching regulator for that purpose.

Thnx i'll read about it

 

[BradtheRad]

Does your microcontroller input have an internal resistance greater than, say 50k?

If so then you can make a resistor divider with high enough values that they will not heat up much. The main dropping resistor can be a common 1/2 watt size.

Your microcontroller input ought not load the divider so much as to affect the reading by more than a few percent.

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