I need an ADC can take Negative voltage

Hello there,    

I have a project that required a bidirectional ADC which can take negative and positive voltages.    

What is the best solution to do so using PSoC 5LP? I have MAXREFDES5#, and I am thinking about using it, but I know the design will be complex. If these is a suggestion or an example code that would help me to build my design faster I would be grateful. 

Thanks!