I have a status and monitoring signal defined with two voltage levels -5 V and 0 V. I need to convert these voltage levels into 0 V and 3.3 V such that they are readable by MCU. The signal level -5 V should be transform to 0 V and the 0 V should be transform to 3.3 V. Which device should I use ?

 

NPN transistor, wired common base.
base connects to 0V.
Input to the emitter via a resistor,
output from the collector with a resistor to 3.3V

 

With optocoupler:

 

There have been level shifting ICs around for many years. I am not sure which, if any, can handle a negative input voltage, though. The selection will depend on if the data input can sink current or source current in either the hi or low modes.
It will be a non-inverting level shifter. If the signal can sink current , then a grounded common base PNP transistor can do it with only a pull-up to 3.3 volts thru a collector resistor. When the emitter is low, base current can flow and so the collector is pulled down. when the emitter is hi the transistor is cut off and the collector is pulled high.

 

I have a status and monitoring signal defined with two voltage levels -5 V and 0 V. I need to convert these voltage levels into 0 V and 3.3 V such that they are readable by MCU. The signal level -5 V should be transform to 0 V and the 0 V should be transform to 3.3 V. Which device should I use ?

Show us the circuit that is generating -5 V. That is unusual today.

 

NPN transistor, wired common base.
base connects to 0V.
Input to the emitter via a resistor,
output from the collector with a resistor to 3.3V

And diode, if needed:

 

And diode, if needed:

If you make R1 = 2.61kΩ, then the low output will be close to zero without D1.

 

OK, Danko got it right!! Not sure why I suggested a PNP transistor, it must have been too late in the evening. BUT that is exactly the circuit to use.

 

Another option would be a N-Channel JFET in common source configuration with a drain pullup resistor to 3.3V. It is inverting but the status/monitor output doesn't have to sink (or source) current.