Method and circuit for catching excess current
Data may be encoded onto a direct current power line by modulating the current on that direct current power line. One method of modulating the current is by placing an inductor on the power line and then using a controlled transistor that turns on and turns off. The inductor will ensure that current keeps flowing but the transistor will induce changes in the current pattern. The excess current from when transistor is turned off must be diverted. Furthermore, to create symmetrical current changes, the inductor should be reverse biased. Thus, a circuit is created that sinks the excess current from when the transistor is turned off and used to reverse bias the inductor.
1. An electronic circuit for sinking excess current and creating a biasing voltage, said electronic circuit comprising:
a power supply circuit for generating a first electrical current at a VSupply voltage;
a load circuit powered by said first electrical current;
an inductor, said first electrical current passing through said inductor;
a main transistor, said main transistor coupled to said inductor for receiving said first electrical current;
a first diode coupled to said inductor in parallel to said main transistor such that said first electrical current passes through said first diode when said main transistor is turned off; and
a catch circuit coupled to said first diode, said catch circuit comprising
a multi-winding transformer, said multi-winding coupled back to said VSupply voltage from said power supply circuit, and
a capacitor;
such that said catch circuit creates a biasing voltage applied to said inductor when said main transistor is turned off.
2. The electronic circuit as set forth in claim 1 wherein said capacitor is coupled to a mid-point of said multi-winding transformer.
3. The electronic circuit as set forth in claim 1 wherein at least one diode couple windings of said multi-winding transformer.
4. The electronic circuit as set forth in claim 1 wherein said load circuit comprises a plurality of individually controlled circuits powered by said first electrical current.
5. The electronic circuit as set forth in claim 4 wherein said main transistor modulates data onto said first electrical current by turning said main transistor on and off, said data used to control said plurality of individually controlled circuits.
6. A method for sinking excess current and creating a biasing voltage in an electronic circuit, said method comprising:
generating a first electrical current at a VSupply voltage with a power supply circuit;
driving a load circuit with said first electrical current;
driving an inductor by passing said first electrical current through said inductor;
controlling said first electrical current with a main transistor coupled to said inductor;
diverting said first electrical current through a first diode coupled to said inductor in parallel to said main transistor when said main transistor is turned off; and
catching said first electrical current passing through said first diode with a catch circuit,
said catch circuit sinking said first electrical current, and
creating a biasing voltage with said first electrical current to bias said inductor;
wherein said catch circuit comprises
a multi-winding transformer, said multi-winding coupled back to said VSupply voltage from said power supply circuit, and
a capacitor.