Switch control systems for light emitting diodes and methods thereof

A method for controlling one or more light emitting diodes, the method comprising:

• generating a first current flowing through the one or more light emitting diodes, the one or more light emitting diodes being configured to receive a rectified voltage generated by a rectifying bridge coupled to a TRIAC dimmer;
• receiving a sensing voltage, the sensing voltage indicating a magnitude of the first current;
• receiving an input voltage, the input voltage indicating a magnitude of the rectified voltage;
• and
• outputting, by a controller, a control signal to the bleeder;
• wherein the outputting a control signal to the bleeder includes:
• generating the control signal, by a flip-flop in the controller, to turn off the bleeder if the input voltage satisfies a first condition so that the bleeder does not generate a second current, the second current being larger than zero in magnitude;
• generating, by the flip-flop in the controller, the control signal to turn on the bleeder if the input voltage satisfies a second condition so that the bleeder generates the second current;
• and
• directly outputting, b the flip-flop in the controller, the control signal;
• wherein the second condition is different from the first condition.

A system for controlling one or more light emitting diodes, the system comprising:

• a current generator configured to generate a first current flowing through the one or more light emitting diodes, the one or more light emitting diodes being configured to receive a rectified voltage generated by a rectifying bridge coupled to a TRIAC dimmer;
• a bleeder configured to receive the rectified voltage;
• and
• a controller configured to:
• receive a sensing voltage from the current generator, the sensing voltage indicating a magnitude of the first current;
• receive an input voltage generated by a voltage divider, the voltage divider being configured to receive the rectified voltage, the input voltage indicating a magnitude of the rectified voltage;
• and
• output a control signal to the bleeder;
• wherein the controller is further configured to:
• generate the control signal at a first logic level from a first tune to a second time, during which the input voltage is smaller than a reference voltage in magnitude;
• generate the control signal at a second logic level from the second time to a third tune, during which the input voltage is larger than the reference voltage in magnitude;
• and
• generate the control signal at the first logic level from the third time to a fourth time, during which the input voltage is smaller than the reference voltage in magnitude;
• wherein the first logic level and the second logic level are different;
• wherein:
• the controller includes a flip-flop;
• and
• the flip-flop is configured to directly output the control signal.

A method for controlling one or more light emitting diodes, the method comprising:

• generating a first current flowing through the one or more light emitting diodes, the one or more light emitting diodes being configured to receive a rectified voltage generated by a rectifying bridge coupled to a TRIAC dimmer;
• receiving a sensing voltage, the sensing voltage indicating a magnitude of the first current;
• receiving an input voltage, the input voltage indicating a magnitude of the rectified voltage;
• and
• outputting, by a controller, a control signal to the bleeder;
• wherein the outputting a control signal to the bleeder includes:
• generating, by a flip-flop in the controller, the control signal at a first logic level from a first time to a second time, during which the input voltage is smaller than a reference voltage in magnitude;
• generating, by the flip-flop in the controller, the control signal at a second logic level from the second time to a third time, during which the input voltage is larger than the reference voltage in magnitude;
• generating, by the flip-flop in the controller, the control signal at the first logic level from the third time to a fourth time, during which the input voltage is smaller than the reference voltage in magnitude;
• and
• directly outputting, b the flip-flop in the controller, the control signal;
• wherein the first logic level and the second logic level are different.