The R5220D is especially designed for applications featuring 3 operational modes like:
• On Mode: application circuit is active and requires high power for full operation. The DCDC Converter is enabled for high efficiency.
• Standby Mode: application circuit is active and requires low power for limited operation. The LDO is enabled for low supply current.
• Off Mode: application circuit is not active and requires minimum power consumption. Power management circuit is disabled.

In the On Mode the R5220D uses the high efficiency of a step down DCDC converter to supply high power to the circuit and to avoid high heat dissipation/large heat sinks compared with a similar solution using an LDO. In the standby mode a traditional DCDC converter is set to a low power mode by switching from a PWM to a VFM or burst mode. A significant disadvantage is that a traditional DCDC converter in low power mode produces LF noise on the output voltage, which may cause interference in the circuit. The R5220D however, uses an LDO with low noise features for this mode. Additionally, an LDO has a much lower current consumption compared with a DCDC converter in low power mode. 

Another issue is the start-up/mode change speed difference when switching between operating modes: the LDO supports the output voltage while the DCDC converter starts up. Moreover, the R5220D’s manual mode change with a mode pin prevents a delay time. A traditional DCDC converter with automatic mode change circuits needs to detect the switchover condition first before changing modes. Some new processors are featuring a lower supply voltage requirement in the standby or sleep mode, the R5220D supports this new feature and can be ordered with individual output voltage setting for the DCDC converter and LDO.

R5220D Features