System power integrated circuit and architecture, management circuit, power supply arrangement, and portable apparatus

According to one embodiment, a management circuit for a portable device includes an input terminal, a first step-up converter, a first step-down converter, and a second step-down converter. The input terminal is coupled to receive a supply voltage from a power supply. The first step-up converter, coupled to the input terminal, selectively converts the supply voltage to a boosted voltage. The first step-down converter, coupled to the first step-up converter, selectively provides a first output power voltage to a first radio frequency (RF) module. The second step-down converter, coupled to the first step-up converter, selectively provides a second output power voltage to a second radio frequency (RF) module. The first step-up converter performs the conversion of the supply voltage when the supply voltage is under a threshold voltage.