Constant off-time control method for buck converters using coupled inductors

A method for operating a voltage regulator unit, the method comprising:

• discharging, for a first time period, a power supply node of a circuit block through a first inductor;
• in response to determining the first time period has expired:
• charging the power supply node through the first inductor;
• and
• discharging, for a second time period, the power supply node through a second inductor, wherein the second inductor is inductively coupled to the first inductor;
• determining a first average voltage at a first output terminal of a first driver circuit coupled to the first inductor during the charging of the power supply node through the first inductor;
• charging the power supply node through the second inductor in response to determining that a third time period has expired since initiating the charging of the power supply node through the first inductor;
• determining a second average voltage at a second output terminal of a second driver circuit coupled to the second inductor during the charging of the power supply node through the second inductor;
• and
• adjusting the second time period using the first average voltage and the second average voltage.

A system, comprising:

• a plurality of circuit blocks;
• and
• a regulator unit including a first inductor coupled to a power supply node of a particular circuit block, a first driver circuit coupled to the first inductor, a second inductor coupled to the power supply node, a second driver circuit coupled to the second inductor, wherein the second inductor is inductively coupled to the first inductor, and wherein the regulator unit is configured to:
• discharge, for a first time period, the power supply node through the first inductor;
• charge the power supply node through the first inductor in response to a determination that the first time period has expired;
• and
• discharge, for a second time period, the power supply node through the second inductor;
• determine a first average voltage at a first output terminal of the first driver circuit while charging the power supply node through the first inductor;
• charge the power supply node through the second inductor in response to a determination that a third time period has expired since a charging of the power supply node through the first inductor was initiated;
• determine a second average voltage at a second output terminal of the second driver circuit while charging of the power supply node through the second inductor;
• and
• adjust the second time period using the first average voltage and the second average voltage.