LED lighting systems with TRIAC dimmers and methods thereof

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

a current regulation circuit configured to receive a rectified voltage and coupled to an anode of one or more light emitting diodes, the one or more light emitting diodes including the anode and a cathode; and

a control circuit configured to receive the rectified voltage;

wherein the control circuit is configured to:

compare an input voltage and a threshold voltage, the input voltage indicating a magnitude of the rectified voltage; and

generate a control signal based at least in part on the input voltage and the threshold voltage;

wherein the control circuit is further configured to:

if the input voltage is larger than the threshold voltage, generate the control signal at a first logic level; and

if the input voltage is smaller than the threshold voltage, generate the control signal at a second logic level;

wherein the current regulation circuit is configured to:

receive the control signal from the control circuit;

allow a current to flow through the one or more light emitting diodes if the control signal is at the first logic level, the current being larger than zero in magnitude; and

not allow the current to flow through the one or more light emitting diodes if the control signal is at the second logic level;

wherein the current regulation circuit includes:

an amplifier including a first amplifier input terminal, a second amplifier input terminal, and an amplifier output terminal;

a transistor including a drain terminal, a gate terminal, and a source terminal; and

a resistor including a first resistor terminal and a second resistor terminal;

wherein:

the drain terminal of the transistor is configured to receive the rectified voltage;

the gate terminal of the transistor is coupled to the amplifier output terminal of the amplifier; and

the source terminal of the transistor is coupled to the anode of the one or more light emitting diodes.

2. The system of claim 1 wherein the input voltage is directly proportional to the rectified voltage in magnitude.

3. The system of claim 1 wherein:

the first logic level is a logic high level; and

the second logic level is a logic low level.

4. The system of claim 1 wherein the first amplifier input terminal of the amplifier is configured to receive a reference voltage.

5. The system of claim 1 wherein the cathode of the one or more light emitting diodes is configured to receive a ground voltage.

6. The system of claim 1 wherein the control circuit includes:

a first resistor including a first resistor terminal and a second resistor terminal;

a second resistor including a third resistor terminal and a fourth resistor terminal, the third resistor terminal being connected to the second resistor terminal; and

a comparator including a first comparator input terminal, a second comparator input terminal, and a comparator output terminal;

wherein:

the first resistor terminal is configured to receive the rectified voltage; and

the fourth resistor terminal is configured to receive a ground voltage;

wherein:

the first comparator input terminal is coupled to the second resistor terminal and the third resistor terminal and configured to receive the input voltage;

the second comparator input terminal is configured to receive the threshold voltage; and

the comparator output terminal is configured to output the control signal based at least in part on the input voltage and the threshold voltage.

7. The system of claim 6 wherein the current regulation circuit further includes:

a transistor including a drain terminal, a gate terminal, and a source terminal; and

a third resistor including a fifth resistor terminal and a sixth resistor terminal;

wherein:

the drain terminal of the transistor is configured to receive the rectified voltage;

the gate terminal of the transistor is coupled to the amplifier output terminal of the amplifier; and

the source terminal of the transistor is coupled to the fifth resistor terminal of the third resistor and the second amplifier input terminal of the amplifier.

8. The system of claim 7 wherein the sixth resistor terminal is coupled to the anode of the one or more light emitting diodes.

9. The system of claim 7 wherein the control circuit further includes:

a switch including a first switch terminal and a second switch terminal;

wherein:

the first switch terminal is connected to the amplifier output terminal of an amplifier; and

the second switch terminal is configured to receive the ground voltage.

10. The system of claim 9 wherein the control circuit is further configured to:

open the switch if the control signal is at the first logic level; and

close the switch if the control signal is at the second logic level.

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

receiving a rectified voltage by a control circuit;

comparing an input voltage and a threshold voltage, the input voltage indicating a magnitude of the rectified voltage;

if the input voltage is larger than the threshold voltage, generating a control signal at a first logic level;

if the input voltage is smaller than the threshold voltage, generating the control signal at a second logic level;

receiving the control signal from the control circuit by a current regulation circuit configured to receive the rectified voltage and coupled to an anode of one or more light emitting diodes, the one or more light emitting diodes including the anode and a cathode;

allowing a current to flow through the one or more light emitting diodes if the control signal is at the first logic level, the current being larger than zero in magnitude; and

not allowing the current to flow through the one or more light emitting diodes if the control signal is at the second logic level;

wherein the current regulation circuit includes:

an amplifier including a first amplifier input terminal, a second amplifier input terminal, and an amplifier output terminal;

a transistor including a drain terminal, a gate terminal, and a source terminal;

and

a resistor including a first resistor terminal and a second resistor terminal;

wherein:

the drain terminal of the transistor is configured to receive the rectified voltage;

the gate terminal of the transistor is coupled to the amplifier output terminal of the amplifier; and

the source terminal of the transistor is coupled to the anode of the one or more light emitting diodes.