PMU IP includes following components: Bandgap reference voltage source, reference current sources and reference frequency generator. Bandgap source forms temperature, power supply and process variations independent voltage.
Reference current sources provide stable output currents which are independent of process/voltage/temperature variations if external resistor is used (CS = “0”) or dependent of process corner and temperature of internal resistor rppd (CS = “1”).
Reference frequency generator could operate in two modes: XTALL mode (OSC_MODE = “0”) and TCXO mode (OSC_MODE = “1”). In XTALL mode external resonator is used, while in TCXO mode external TCXO provides input frequency signal, which is buffered and additionally divided. There are two output frequencies: undivided reference frequency (CLK_REF output) and programmable (OSC_CDiv<7:0>) divided frequency (CLK_REF_DIV). To achieve 50% duty cycle at CLK_REF_DIV output there is additional division-by-two stage embedded in frequency divider, which is turned on by OSC_Div2 = “1”.