Switch control systems for light emitting diodes and methods thereof

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

• a current generator configured to generate a first current flowing through 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 time to a second time, during which the sensing voltage is smaller than a first reference voltage in magnitude and the input voltage is smaller than a second reference voltage in magnitude;
• generate the control signal at a second logic level from the second time to a third time, during which the sensing voltage is larger than the first reference voltage in magnitude and the input voltage is larger than the second reference voltage in magnitude;
• and
• generate the control signal at the second logic level from the third time to a fourth time, during which the sensing voltage is smaller than the first reference voltage in magnitude and the input voltage is larger than the second reference voltage in magnitude;
• wherein the first logic level and the second logic level are different.

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

• generating a first current flowing through 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 the rectified voltage;
• receiving a sensing voltage, the sensing voltage indicating a magnitude of the first current;
• and
• outputting a control signal to a bleeder;
• wherein the outputting the control signal to the bleeder further includes:
• generating a comparison signal based on the sensing voltage and the reference voltage;
• generating, by a delay circuit, the control signal based on the comparison signal, the delay circuit including a single input terminal, the single input terminal of the delay circuit directly coupled to the comparison signal;
• and
• outputting, by the delay circuit, the control signal.

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

• generating a first current flowing through 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 a control signal to the bleeder;
• wherein the outputting the control signal to the bleeder further includes:
• generating the control signal at a first logic level from a first time to a second time, during which the sensing voltage is smaller than a first reference voltage in magnitude and the input voltage is smaller than a second reference voltage in magnitude;
• generating the control signal at a second logic level from the second time to a third time, during which the sensing voltage is larger than the first reference voltage in magnitude and the input voltage is larger than the second reference voltage in magnitude;
• and
• generating the control signal at the second logic level from the third time to a fourth time, during which the sensing voltage is smaller than the first reference voltage in magnitude and the input voltage is larger than the second reference voltage in magnitude;
• wherein the first logic level and the second logic level are different.