Holding current circuits for phase-cut power control

A holding current circuit for maintaining at least a holding current in a dimmer, the circuit connectable to the dimmer and connectable to a load connected to draw current from the dimmer, the circuit comprising:

• a controlled current source connectable to draw current from the dimmer in accordance with a control signal;
• a conduction monitor operable to generate a conduction monitor signal indicative of a conduction state of the dimmer;
• a current monitor connected to receive at least a portion of the current drawn by the controlled current source and connectable to receive at least a portion of a load current drawn from the dimmer by the load, the current monitor operable to generate a current monitor signal indicative of a magnitude of the current in the current monitor;
• and
• a current controller configured to generate the control signal based on the conduction monitor signal and the current monitor signal to cause the controlled current source to draw a supplementary current at least as great as a difference between the holding current and the load current when the dimmer is in conduction and the load current is less than the holding current
• wherein the current controller comprises a conduction dependent reference signal source and a subtractor, the conduction dependent reference signal source configured to generate a conduction dependent reference signal based on the conduction monitor signal, the subtractor configured to generate the control signal based on a difference between the conduction dependent reference signal and the current monitor signal.

An LED lighting assembly connectable to a dimmer, the assembly comprising:

• an LED lighting module connectable to draw a load current from the dimmer;
• a holding current circuit comprising:
• a controlled current source connectable to draw current from the dimmer in accordance with a control signal;
• a conduction monitor operable to generate a conduction monitor signal indicative of a conduction state of the dimmer;
• a current monitor connected to receive at least a portion of the current drawn by the controlled current source and connected to receive at least a portion of the load current, the current monitor operable to generate a current monitor signal indicative of a magnitude of the current in the current monitor;
• and
• a current controller configured to generate the control signal based on the conduction monitor signal and the current monitor signal to cause the controlled current source to draw a supplementary current at least as great as a difference between the holding current and the load current when the dimmer is in conduction and the load current is less than the holding current;
• and
• an excess current bypass configured to shunt current in excess of an excess current threshold away from the current monitor.