Keeping current consumption at a minimum level ensures longer battery life and reduces maintenance cost. Since battery operated systems like temperature sensors, or gas and water meters spend most of their time in sleep, the system sleep current consumption is a significant factor in calculating battery life. The ATmega128RFA1 offers sleep current consumption of less than 250nA. Even though the device spends most of its time in sleep mode, efficient transition from sleep to active mode, and vice versa, is an important factor in keeping the system power consumption figures to an absolute minimum. The ATmega128RFA1 microcontroller core wakes up from sleep in less than 70µs, while the RF device is ready to receive in less than 420µs. This includes 70µs for the microcontroller to wake up, and 240µs + 110µs for the transceiver to switch from sleep to PLL_ON via the TRX_OFF state.