8.7 Power Supply Modes

The PIC32CX-BZ6 device supports a single power supply from 1.9–3.6V. The IO supply cannot be decoupled from the main supply. The same voltage must be applied to VDDx, PMU_VDDIO, VPMU_VDDC and AVDD with different levels of filtering. The system has the following different modes:

• RUN mode – The PIC32CX-BZ6 device automatically enters RUN mode upon power-up. This is the default state of the device.
  • MLDO mode – Provide a soft start-up by using the MLDO, limiting the charging current. The MLDO also helps to extend the supply voltage range down to 1.9V below Buck BOR. This mode does not require an external inductor.
  • BUCK mode – The most efficient mode when the CPU and peripherals are running. In this mode, the DC-DC converter powers the SoC. This mode requires external LC-filtering and appropriate decoupling on-board before supplying power to other blocks.

    BUCK mode has the following two operating modes:

    • PWM (Pulse Width Modulation) mode – Buck can deliver the highest output current with good efficiency. The internal switching clock in this mode is 1-2 MHz. In PWM mode, it is expected to reach an efficiency of 85%.
    • PSM (Pulse Skipping Mode) – This mode is recommended when the load current demand is low. The PSM mode is a type of frequency modulation scheme with an efficiency of up to 80%.
• Low-power modes – The PIC32CX-BZ6 supports various low-power modes; Sleep, Deep-Sleep (DS) and Extreme Deep Sleep (XDS). See Power Management Unit (PMU) from Related Links for more details on how to transition from RUN mode to low-power modes.
• IDLE mode – See Power Management Unit (PMU) from Related Links.

The on-the-fly software can do the selection between Switching (BUCK) mode and Linear (MLDO) mode. Be sure to design the power supply according to the type of mode in use.