Description

This reference design demonstrates an ultra-small power supply solution (8.5 mm2 total) for an efficient and low-noise rail in portable personal electronic devices: such as wearables: smart watches: smartphones: headsets: headphones: earbuds: and camera modules. A low dropout (LDO) linear regulator follows a DC/DC converter to deliver the same low-noise performance of an LDO with the high efficiency of a DC/DC converter. The overall no load input current (also known as switching IQ) of only 8 µA maintains higher efficiency than an LDO-only based design: while the near 100-µV output noise cleanly powers the sensitive load better than a DC/DC-only design. This design guide documents and compares the critical performance characteristics: such as efficiency: IQ: ripple: and so forth: of all three design types: LDO only: DC/DC only: and LDO after DC/DC.