An integrated circuit device controls power up of an external device used for sensing a process variable independently of whether the integrated circuit device is in a low power sleep mode. Once the external device becomes operational the integrated device, even when still in the low power sleep mode, samples the process variable status of the external device. Low power timing circuits operational during the low power sleep mode control the power up of the external device and sampling of the process variable status thereof. After the sample of the process variable status is taken, the integrated circuit device may be brought out of the low power sleep mode to an operational mode when appropriate as determined from the sampled process variable status.