Apparatus and Method for Multi-Phase Power Converter in Light Load Operating Mode

A method comprising:

• generating a first reset signal for determining a turn-off time instant of a high-side switch of a first phase of a multi-phase power converter;
• generating, by a first comparator, a first set signal for determining a turn-on time instant of the high-side switch of the first phase based on a comparison between a first current sense signal and a voltage control signal;
• detecting, by a first zero-crossing detection circuit, a zero-crossing of an inductor current in a first output inductor of the first phase;
• and
• generating, by a first phase offset voltage generator, a first offset voltage being used to configure the first phase to exit a first continuous conduction mode in response to the zero-crossing of the inductor current in the first phase.

A power converter comprising:

• a first step-down converter comprising a first high-side switch, a first low-side switch, and a first inductor;
• a second step-down converter comprising a second high-side switch, a second low-side switch, and a second inductor;
• and
• a control apparatus comprising:
• a first on-timer configured to produce a first reset signal for determining an on-time duration of the first high-side switch;
• a first comparator configured to produce a first set signal for determining a turn-on time instant of the first high-side switch based on a comparison between a first current sense signal and a voltage control signal;
• a first zero-crossing detection circuit configured to detect a zero-crossing of the current through the first inductor;
• a first phase offset voltage generator configured to produce a first offset voltage used to configure the first step-down converter to exit a first continuous conduction mode in response to the zero-crossing of the current through the first inductor;
• a second on-timer configured to produce a second reset signal for determining the on-time duration of the second high-side switch;
• a second comparator configured to produce a second set signal for determining a turn-on time instant of the second high-side switch based on a comparison between a second current sense signal and a voltage control signal;
• a second zero-crossing detection circuit configured to detect a zero-crossing of the current through the second inductor;
• and
• a second phase offset voltage generator configured to produce a second offset voltage used to configure the second step-down converter to exit continuous conduction mode in response to the zero-crossing of the current through the second inductor, wherein the first offset voltage is greater than the second offset voltage, the second phase exiting the second continuous conduction mode before the first phase exits the first continuous conduction mode.