SWRS232D February 2019 – February 2021 CC2652RB
The CC2652RB device has several internal system clocks.
The 48 MHz SCLK_HF is used as the main system (MCU and peripherals) clock. This can be driven by the internal 48 MHz RC Oscillator (RCOSC_HF), the internal BAW resonator, or an external 48 MHz crystal (XOSC_HF). Radio operation requires either the internal BAW resonator or an external 48 MHz crystal.
SCLK_MF is an internal 2 MHz clock that is used by the Sensor Controller in low-power mode and also for internal power management circuitry. The SCLK_MF clock is always driven by the internal 2 MHz RC Oscillator (RCOSC_MF).
The BAW oscillator clock frequency is actively compensated by the modem internal firmware to ensure frequency stability over temperature, voltage and device lifetime. Every time the PLL is tuned (wakeup of radio from idle/standby or tuned to a difference frequency) the modem firmware considers the BAW device characteristics stored on the device along with current temperature and voltage conditions and configures the PLL to compensate accordingly. The RF frequency accuracy around the desired center frequency is +/-40ppm across temperature.
SCLK_LF is the 32.768 kHz internal low-frequency system clock. It can be used by the Sensor Controller for ultra-low-power operation and is also used for the RTC and to synchronize the radio timer before or after Standby power mode. SCLK_LF can be driven by the internal 32.8 kHz RC Oscillator (RCOSC_LF), a 32.768 kHz watch-type crystal, the internal BAW resonator, an external 48 MHz crystal, or a clock input on any digital IO.
When using a crystal or the internal RC oscillator, the device can output the 32 kHz SCLK_LF signal to other devices, thereby reducing the overall system cost.