Voltage regulator with enhanced transient regulation and low-power sub regulator

A voltage regulator circuit, comprising:

• a reference input to receive a reference voltage;
• a first error amplifier coupled to the reference input, the first error amplifier comprising an output indicative of a first difference between a representation of the reference voltage received from the reference input, and a representation of an output voltage of the voltage regulation circuit;
• a pass device coupled to the output of the first error amplifier, the pass device arranged to supply an output of the voltage regulation circuit;
• and
• an open-loop regulation circuit separate from a loop corresponding to the first error amplifier.

A voltage regulator circuit comprising:

• a main regulator circuit loop including:
• a first error amplifier including an input coupled to an output of the voltage regulation circuit;
• and
• a pass device coupled to the output of the first amplifier circuit and the output of the voltage regulation circuit, the first error amplifier to regulate an output voltage at the output of the voltage regulation circuit;
• and
• a secondary circuit loop including:
• a second error amplifier having higher gain than the first error amplifier circuit and including an input operatively coupled to the output of the voltage regulation circuit;
• a shunt device having a shunt input coupled to the pass device and a control input coupled to the output of the second error amplifier;
• and
• wherein second error amplifier activates the shunt device to bypass a load at the output of the regulation circuit when the output voltage overshoots a target output voltage.