Efficient electrically-isolated power circuits with application to light sources

A power circuit comprising:

• a first part and a second part that are galvanically isolated from one another;
• a switching mode power supply having a primary side in the first part of the power circuit and a secondary side in the second part of the power circuit, the primary side connected to receive electrical power from a power input, the secondary side connectable to supply electrical power to drive a load comprising one or more solid-state light emitters;
• a primary side control in the first part of the power circuit, the primary side control connected to control operation of the primary side of the switching mode power supply;
• a control circuit in the second part of the power circuit, the control circuit configured to generate a primary side control signal for the primary side control;
• a first galvanic isolator configured to carry the primary side control signal from the control circuit to the primary side control;
• a monitoring circuit in the first part of the power circuit, the monitoring circuit configured to monitor one or more characteristics of the electrical power from the power input and to generate an information signal carrying information derived from the one or more monitored characteristics;
• and,
• a second galvanic isolator configured to carry the information signal from the monitoring circuit to the control circuit;
• wherein all of the secondary side of the switching mode power supply and the control circuit are galvanically isolated from the primary side of the switching mode power supply and the primary side control.