Power Supply Scheme

UC6580 supports two power supply schemes, including internal DC-DC mode and LDO mode.

If you do not use the hot start and backup function, connect the V_BACK to VDD_IO.

DC-DC Mode

In this mode, the main power (V_Main) connects to the pin DCDC_IN, and the output of the DCDC module DCDC_Out provides the power to the rest circuits. At this time, the system is powered by the internal DC-DC:

• DCDC_IN and VDD_IO use the same power.
• V_BACK can use an independent power, or use the same power as DCDC_IN and VDD_IO.
• The system power supply is input by DCDC_IN, and DCDC_Out is connected to the V_CORE input pin.
• TCXO is powered by LDO_X. The voltage could be 1.8 V or 2.8 V.

LDO Mode

In this mode, the main power (V_Main) connects to DCDC_IN while DCDC_IN and DCDC_Out are short-circuited and the internal DC-DC is bypassed, so that the V_Main provides the power to the rest circuits directly. At this time:

• DCDC_IN and DCDC_OUT are short-circuited together.
• DCDC_IN and VDD_IO use the same power.
• V_BACK can use an independent power, or use the same power as DCDC_IN and VDD_IO.
• The system power supply is input by VDD_IO and output to V_CORE through LDO_EX.
• TCXO is powered by LDO_X. The voltage could be 1.8 V or 2.8 V.

For specific design scheme of the above modes, please refer to UC6580 Hardware Reference Design.