1. A phase circuit comprising: a bidirectional output stage configured to be coupled between a first battery and a second battery; a memory configured to store a number of active phases, and an identifier; and a synchronization circuit configured to receive a first clock signal and determine a start time of a switching cycle of the bidirectional output stage based on the number of active phases, the identifier, and the first clock signal, wherein the phase circuit is configured to control the timing of the switching of the bidirectional output stage based on the start time, wherein the synchronization circuit comprises: a phase shift circuit configured to generate a phase shift value based on a peak value, the number of active phases and the identifier, a first comparator configured to set a flip-flop when a reference ramp value becomes higher than the phase shift value, a second counter having a reset input coupled to an output of the first comparator, a clock input configured to receive a oscillator signal, and an output configured to provide a shifted ramp value, and a second comparator configured to reset the flip-flop when the shifted ramp value becomes higher than an on-time value.