Power supply apparatus and method for a backlight system

A backlight system for providing backlight to a display device, the backlight system comprising:

• a transformer having a primary winding on its primary side for coupling to a power source and one or more secondary windings on its secondary side;
• a first control circuit disposed on the primary side of the transformer for controlling a current flow in the primary winding;
• and
• a second control circuit disposed on the secondary side of the transformer, the second control circuit being configured to provide a regulated output voltage;
• and
• a backlight apparatus that includes one or more light devices;
• wherein the first control circuit is configured to generate a control signal for controlling the current flow in the primary winding without using a feedback control signal from the secondary side of the transformer;
• wherein the second control circuit comprises a pulse width modulated (PWM) control circuit.

A power supply system, comprising:

• a transformer having a primary winding on its primary side for coupling to a power source and one or more secondary windings on its secondary side;
• a first control circuit disposed on the primary side of the transformer for controlling a current flow in the primary winding, the first controller including an LLC resonant circuit, the first controller including a pulse width modulated (PWM) control circuit configured to operate at a frequency for a peak voltage gain for a target load condition;
• and a second control circuit disposed on the secondary side of the transformer, the second control circuit being configured to provide a regulated output voltage;
• wherein the first control circuit is configured to generate a control signal for controlling the current flow in the primary winding without using a feedback control signal from the secondary side of the transformer.