Power supply circuit including first and second voltage regulators, corresponding device and method for controlling actuation of the voltage regulators in multiple operation modes

A circuit, comprising:

• a first node;
• a second node configured to provide electrical supply power to an electrically powered device;
• a voltage regulator coupled to the first node and configured to provide a regulated voltage to the second node, said voltage regulator including first regulator circuitry configured to provide full-power operation of the voltage regulator and second regulator circuitry configured to provide low-power operation of the voltage regulator;
• wherein the circuit is configured to operate:
• i) in a first mode of operation wherein:
• when a voltage at said first node is at a first voltage level, said first regulator circuitry in the voltage regulator is activated with said second regulator circuitry inactive and when the voltage at said first node is at a second voltage level the voltage regulator is kept de-activated;
• ii) in a second mode of operation wherein:
• when the voltage at said first node is at said first voltage level, said first regulator circuitry in the voltage regulator is active with said second regulator circuitry inactive and when the voltage at said first node is at said voltage the voltage regulator is inactive with both the first voltage regulator circuitry and the second regulator circuitry inactive;
• and
• iii) in a third mode of operation, the second regulator circuitry in the voltage regulator is active and said first regulator circuitry is inactive irrespective of the voltage at said first node being at said first voltage level or at said second voltage level;
• and
• a supply node configured to be coupled to said electrically powered device, wherein said supply node is configured to be coupled, in response to the voltage regulator being inactive, to a power supply source selected from the group consisting of:
• a further voltage regulator external to the circuit, wherein the further voltage regulator is coupled to a voltage source at said first voltage level, and a voltage source at said first voltage level.