Dual Power Supply Microcontroller

[meles]

Hi,

I am currently working on a project that requires a microcontroller with internal ADCs. The ADCs need to work on full differential mode and they need to support negative inputs. All the microcontrollers that I've used in the past are single supply and therefore none of their inputs can be negative. Does anybody know of a microcontroller that would help me with this?

Thanks

 

[Nigel Goodwin]

Hi,

I am currently working on a project that requires a microcontroller with internal ADCs. The ADCs need to work on full differential mode and they need to support negative inputs. All the microcontrollers that I've used in the past are single supply and therefore none of their inputs can be negative. Does anybody know of a microcontroller that would help me with this?

No, and there's no requirement for one!. Use an opamp to shift the signal to be single ended.

Assuming the A2D is 0-5V, then a 0V input gives 2.5V to the A2D, a -2.5V input gives 0V, and a +2.5V input gives 5V. You can alter the gain of the opamp (or an attenuator at it's input) to alter the range from -2.5V/+2.5V.