Systems and methods for multi-state switch networks
Systems and methods for multi-state switch networks and multi-state LED networks are provided. Systems and methods for maintaining the brightness of LEDs in multi-state LED networks are also provided. The multi-state networks contain control circuitry that can output a single control signal that is able to drive a pair of diodes in three different states. In a network of 2*N diodes, N wires are sufficient to drive the diodes in 3^N different states. The control circuitry may also include a pulse-width modulator that controls the perceived brightness of the LEDs in a multi-state LED network in response to a voltage level of the power source.
1. A multi-state switch network comprising:
a serially-connected diode pair that receives a single control signal at a control node;
wherein the single control signal is operative to drive the serially-connected diode pair to one of at least three different states; and
wherein the single control signal is operative to alternatively:
turn ON a first diode of the diode pair and turn OFF a second diode of the diode pair when the single control signal is in a first state;
turn OFF the first diode and turn ON the second diode when the single control signal is in a second state; and
turn OFF the first diode and turn OFF the second diode when the single control signal is in a third state, wherein the third state comprises a high impedance state.
2. The multi-state switch network of claim 1 , wherein the serially-connected diode pair comprises a pair of LEDs.
3. The multi-state switch network of claim 2 , comprising a pulse-width modulator that modulates the single control signal to control a perceived brightness level of the pair of LEDs.
4. The multi-state switch network of claim 3 , wherein the pulse-width modulator is operative to adjust a duty cycle of the single control signal based on a monitored voltage level.
5. The multi-state switch network of claim 4 , wherein the pulse-width modulator is operative to increase the duty cycle of the single control signal based on a decrease in the monitored voltage level.
6. The multi-state switch network of claim 4 , wherein the pulse-width modulator is operative to decrease the duty cycle of the single control signal based on an increase in the monitored voltage level.
7. The multi-state switch network of claim 1 , wherein the serially-connected diode pair is operative to control a pair of switches.
8. The multi-state switch network of claim 1 , wherein:
the first state comprises a higher voltage state; and
the second state comprises lower voltage state.
9. The multi-state switch network of claim 1 , wherein the serially-connected diode pair consists essentially of two diodes and two resistors in serial communication.
10. The multi-state switch network of claim 1 , comprising a tri-state buffer that provides the control signal.
11. A plurality of serially-connected diode pairs as defined in claim 1 , each of the serially-connected diode pairs controlled by a single control signal.
12. The multi-state switch network of claim 1 , wherein the second state comprises a high voltage state.
13. The multi-state switch network of claim 1 , wherein the first state comprises a low voltage state.
14. The multi-state switch network of claim 1 , comprising:
a power source;
a ground source; and
a control node, wherein:
a first diode of the diode pair is serially coupled between the power source and the control node;
a second diode of the diode pair is serially coupled between the control node and the ground source; and
the diode pair receives the single control signal at the control node.
15. The multi-state switch network of claim 14 , comprising:
a first resistor; and
a second resistor, wherein:
the first resistor is serially coupled between the first diode and the control node; and
the second resistor is serially coupled between the second diode and the control node.
16. The multi-state switch network of claim 14 , comprising a first switch node serially coupled between the first diode and the control node.
17. The multi-state switch network of claim 16 , comprising a first switch coupled to the first switch node.
18. The multi-state switch network of claim 17 , wherein the first switch comprises one of a transistor switch, a buffer, and a logic circuit.
19. The multi-state switch network of claim 17 , comprising:
a second switch node serially coupled between the second diode and the control node; and
a second switch coupled to the first switch node.
20. A method of controlling a multi-state switch network comprising first and second diodes, the method comprising:
receiving a single control signal at a control node;
in response to the single control signal, alternatively:
turning ON the first diode and turning OFF the second diode when the single control signal is in a first state;
turning OFF the first diode and turning ON the second diode when the single control signal is in a second state; and
turning OFF the first diode and turning OFF the second diode when the single control signal is in a third state, wherein the third state comprises a high impedance state.
21. The method of claim 20 , wherein the first diode and the second diode are LEDs.
22. The method of claim 21 , comprising pulse-width modulating the single control signal to control a perceived brightness level of the LEDs.
23. The method of claim 22 , comprising:
monitoring a voltage level of a power source; and
adjusting a duty cycle of the control signal based on the monitored voltage level.
24. The method of claim 20 , comprising:
switching a first switch in response to turning ON the first diode; and
switching a second switch in response to turning ON the second diode.