
Having ultra-low sleep current is vital for applications with a small power budget. Systems with battery-operated wireless nodes (RFID, security, smart metering, etc.) wake up periodically, quickly perform measurements, transmit data and then go back to sleep to conserve power. In sleep modes the C8051F91x/0x enters an ultra-low current state, preserving the contents of all the registers and SRAM. The real-time clock (RTC) is active so the MCU can wake up periodically using either the internal low power oscillator (C8051F912/02 only) or an external crystal source.