LED dimming device and LED dimming and driving circuit
A LED dimming device, and a LED dimming and a driving circuit using such LED dimming device are discussed. In present embodiment, the LED dimming device multiplexes an inputting switch and/or a sampling module of the LED driving circuit for dimming. such LED dimming device will not affect the sine waves of input current, in such a way, power factor and work efficiency will be increased while the harmonic coefficient and interference signal will be reduced.
1. A LED dimming device connected with a LED driving circuit and comprising:
a dimming action module for generating a dimming action signal;
a dimming action detector for generating a dimming instruction voltage based on the dimming action signal;
a dimming action determining module for generating a dimming state changing signal or a resetting signal based on the dimming instruction voltage; and
a dimming state control module for generating a LED current control signal for controlling a current of the LED based on the dimming state changing signal or clearing stored dimming state information based on the resetting signal;
wherein, the dimming action detector comprises:
a comparator for receiving a reference voltage via a positive terminal and coupling the dimming action detector via a negative terminal;
an oscillator for generating a timing pulse;
an AND gate for coupling the oscillator via a first inputting terminal and coupling an outputting terminal of the comparator via a second inputting terminal;
a counter for coupling an outputting terminal of the AND gate via a counting terminal, coupling the outputting terminal of the comparator via a resetting terminal, and outputting the resetting signal via an outputting terminal; and
an inverter for coupling the outputting terminal of the comparator via an inputting terminal, and outputting the dimming state changing signal via an outputting terminal.
2. The LED dimming device according to claim 1 , wherein, further comprising a digital-to-analog converter for converting a digital LED current control signal generated by the dimming state control module to an analog LED current control signal.
3. The LED dimming device according to claim 1 , wherein, the dimming action module multiplexes an inputting switch of the LED driving circuit.
4. The LED dimming device according to claim 3 , wherein, the inputting switch is connected between an AC input terminal and a rectification module of the LED driving circuit.
5. The LED dimming device according to claim 3 , wherein, the dimming action detector multiplexes a sampling module of the LED driving circuit.
6. The LED dimming device according to claim 5 , wherein, the sampling module comprises a first sampling resistor, a second sampling resistor and a sampling capacitor, wherein the first sampling resistor and the second sampling resistor are connected in series between an outputting terminal of the rectification module and ground, the connection point of the first sampling resistor and second sampling resistor outputs the dimming instruction voltage, the sampling capacitor is connected between the connection point and ground.
7. A LED dimming and driving circuit comprising a LED driving circuit and a LED dimming device connected with the LED driving circuit and comprising:
a dimming action module for generating a dimming action signal;
a dimming action detector for generating a dimming instruction voltage based on the dimming action signal;
a dimming action determining module for generating a dimming state changing signal or a resetting signal based on the dimming instruction voltage; and
a dimming state control module for generating a LED current control signal for controlling a current of the LED based on the dimming state changing signal or clearing stored dimming state information based on the resetting signal;
the dimming action detector comprises:
a comparator for receiving a reference voltage via a positive terminal and coupling the dimming action detector via a negative terminal;
an oscillator for generating a timing pulse;
an AND gate for coupling the oscillator via a first inputting terminal and coupling an outputting terminal of the comparator via a second inputting terminal;
a counter for coupling an outputting terminal of the AND gate via a counting terminal, coupling the outputting terminal of the comparator via a resetting terminal, and outputting the resetting signal via an outputting terminal; and
an inverter for coupling the outputting terminal of the comparator via an inputting terminal, and outputting the dimming state changing signal via an outputting terminal.
8. The LED dimming and driving circuit according to claim 7 , wherein, the LED dimming device further comprises a digital-to-analog converter for converting a digital LED current control signal generated by the dimming state control module to an analog LED current control signal.
9. The LED dimming and driving circuit according to claim 7 , wherein, the dimming action module multiplexes an inputting switch of the LED driving circuit.
10. The LED dimming and driving circuit according to claim 9 , wherein, the inputting switch is connected between an AC input terminal and a rectification module of the LED driving circuit.
11. The LED dimming and driving circuit according to claim 7 , wherein, the dimming action detector multiplexes a sampling module of the LED driving circuit.
12. The LED dimming and driving circuit according to claim 11 , wherein, the sampling module comprises a first sampling resistor, a second sampling resistor and a sampling capacitor, wherein the first sampling resistor and the second sampling resistor are connected in series between an outputting terminal of the rectification module and ground, the connection point of the first sampling resistor and second sampling resistor outputs the dimming instruction voltage, the sampling capacitor is connected between the connection point and ground.