Measuring high voltage

[santhosh1426471515 0]

I would like to read high voltage (~100V DC) using C2000 launchpad for a closed loop operation of a power converter. Since the launchpad cannot take such high voltage, I must use a signal conditioning circuit. Most people suggest me to use a voltage divider. But i think that even if i use voltage divider, I must isolate the high voltage from the launchpad. How safe is to use a voltage divider? Could some one help me on this issue? 

[PowerRanger 0]

Hi,

You cannot have an isolation if your power ground and your digital ground are the same.

 

In case you want an isolation, you can use any isolation amplifier like the ISO130 between your resistive attenuator and the analog pin of your controller.

 

For total isolation between the power ground and the controller's ground, you must ensure that you have an auxilliary supply to drive the input(Power Side) and another one to power up the output (Controller side) of the isolation amp. Also you need to make sure that the driver used to drive your power switch is also isolated.

 

In short, Common ground for power, Input side of Isolation Amp, Output side of Driver IC.

 

And the second common ground for Output of Isolation Amp, Controller and Input of Driver IC.