Voltage Regulator with Optimal Efficiency Selection and a Master-Slave Zero Cross Detection Configuration

A voltage regulator comprising:

• a first phase power stage including a zero cross detection circuit configured to measure a current level for the first phase power stage, and to cause a diode emulation state in the first phase power stage when the current level is substantially equal to zero;
• a second phase power stage in communication with the zero cross detection circuit, the second phase power stage configured to enter the diode emulation state in response to receiving a signal from the zero cross detection circuit;
• and
• a controller coupled to the first phase power stage and to the second phase power stage, the controller configured to measure an output current of the voltage regulator and to activate the second phase power stage when the output current is above a first threshold current level.

A method comprising:

• enabling a first phase power stage and a second phase power stage in a voltage regulator;
• detecting that an output current of the voltage regulator is below a first threshold current;
• disabling the third phase power stage when the output current of the voltage regulator is below the first threshold current;
• measuring a current in a first low side transistor in the first phase power stage;
• detecting that the current in the first low side transistor is below a zero detect threshold;
• setting a flag in the voltage regulator when the current in the first low side transistor is below a zero detect threshold;
• detecting, in the first phase power stage and the second phase power stage, that the flag is set;
• and
• disabling the first low side transistor in the first phase power stage and a second low side transistor in the second phase power stage when the flag is set.