The graph shown in this slide illustrates the activity profiles of three different MCUs and the effect each has on the overall average current consumption. The red (or top plot) represents an MCU that has a high sleep mode current, slow wake up time and high active mode current. This leads to a high average current value as shown by the red dotted line on the left.  Contrast this activity profile with that of the MCU represented by the green line (bottom plot). This MCU has low sleep mode current, fast wake-up time and low active mode current which results in a low average current value shown by the green dotted line (bottom dotted line). Many products wake-up periodically to sample a sensor output using the on-chip ADC. It is important to allow enough time for the analog circuitry to settle in order to take a valid ADC measurement. The C8051F9xx can wake-up from sleep mode with the analog circuitry settled in less than 2 µS.  That is fifteen times faster than the nearest competitor, allowing the C8051F9xx to capture the necessary sensor output and go back to sleep before the competition can start a valid capture. The mission when designing the C8051F9xx product family was to significantly reduce the amount of energy needed for typical battery operated devices. In order to accomplish that goal the C8051F9xx needed to offer lower power sleep and active modes, operate over the full battery range, and wake-up quickly. Silicon Labs has achieved activity profiles representative of the green lines shown in the graph.