Circuit apparatus for driving light emitting diode with low voltage
A circuit apparatus for driving a light emitting diode with a low voltage is disclosed. The circuit apparatus includes an NPN transistor, a PNP transistor, a capacitor connected to a base of the NPN transistor, a resistor connected to a contact point between the base of the NPN transistor and the capacitor and connected to the power, and an inductor connected to the power ground and a collector of the PNP transistor.
1. A circuit apparatus for driving a light emitting diode (LED) and being energized by a power source, comprising:
a first transistor;
a second transistor;
a capacitor connected to a base of said first transistor and to a collector of said second transistor;
a resistor connected to a contact point between said base of said first transistor and said capacitor and connected to said power source;
an inductor for using said power source with a low supply voltage to generate a high negative pulse voltage on a contact point between said collector of said second transistor and said inductor connected to a power ground and said collector of said second transistor;
an anode of said LED connected to said power source;
a cathode of said LED connected to a contact point of said collector of said second transistor and said inductor;
an emitter of said first transistor connected to said power ground;
a collector of said first transistor connected to a base of said second transistor;
a first end of said inductor connected to said collector of said second transistor, and a second end of said inductor connected to said power ground; and
an emitter of said second transistor connected to said power source,
wherein said negative pulse voltage formed on a contact point between said second transistor and said inductor has an absolute value higher than an activating voltage of said LED.
2. The circuit apparatus as claimed in claim 1 , wherein said first and second transistors are an NPN and a PNP type transistors, respectively.
3. The circuit apparatus as claimed in claim 1 , wherein said LED is driven by said circuit apparatus with said low supply voltage plus said absolute value of said negative pulse voltage.
4. The circuit apparatus as claimed in claim 1 , wherein said inductor is affected by a self-stimulating oscillation.
5. A circuit apparatus for driving a light emitting diode (LED) and being energized by a power source, comprising:
an NPN transistor;
a PNP transistor;
a capacitor connected to a base of said NPN transistor and to a collector of said PNP transistor;
a resistor connected to a contact point between said base of said NPN transistor and said capacitor and said power source;
an inductor for using said power source with a low operating voltage to generate a high negative pulse voltage on a contact point between said collector of said PNP transistor and said inductor connected to a power ground and said collector of said PNP transistor;
an anode of said LED connected to said power source;
a cathode of said LED connected to a contact point of said collector of said PNP transistor and said inductor;
an emitter of said NPN transistor connected to said power ground;
a collector of said NPN transistor connected to a base of said PNP transistor;
a first end of said inductor connected to said collector of said PNP transistor, and a second end of said inductor connected to said power ground; and
an emitter of said PNP transistor connected to said power source,
wherein said negative pulse voltage formed on a contact point between said PNP transistor and said inductor has an absolute value higher than an activating voltage of said LED.