System bus with variable output power supply

• US 8,694,817 B2
• Filed: 06/15/2011
• Issued: 04/08/2014
• Est. Priority Date: 06/15/2011
• Status: Active Grant

• Current Assignee: Digital Lumens, Inc. (Ams-Osram AG)
• Original Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Inventors: Hoffknecht, Marc, Rojas, Javier Orlando, O'Hagan, Liam John
• Primary Examiner(s): DU, THUAN N
• Application Number:
  US13/161,314
• Publication Number:
  US 20120324257A1
• Time in Patent Office: 1,028 Days
• Field of Search: 713/300, 713/310, 713/340, 323/220, 323/234, 323/299, 323/233, 323/293
• US Class Current: 713/340
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 12/40045 Details regarding the feeding of energy to the node from the bus
• CPC Class Codes: H05B 47/14 by determining electrical parameters of the light source

Abstract

A power supply according to various embodiments of the disclosure is configured to detect an event and, in response to the event, alternately supply power to a plurality of provided devices via a provided bus at a first current level or at a second current level, the second current level less than the first current level. Among other things, embodiments in this disclosure help allow additional devices to be used on a bus, even where the total power consumption of the devices would normally exceed a maximum defined by a bus architecture. Furthermore, various embodiments help allow a single gauge of wire to be used throughout a bus network (even where long lengths of wire are required) while still providing sufficient power to the devices connected to the bus.

Claims

1. A system comprising:

a system bus;

a plurality of devices, wherein each device in the plurality of devices is connected to the system bus and is configured to communicate with other devices in the plurality of devices via the system bus; and

a power supply connected to the system, wherein the power supply is configured to supply power to the plurality of devices via the system bus at a first current level and at a second current level, to detect a first change event associated with a device in the plurality of devices and in response to supply power to the plurality of devices at the second current level, and to detect a second change event associated with the device in the plurality of devices and in response to supply power to the plurality of devices at the first current level, wherein the power supply comprises;

a power supply input configured to receive an input voltage;

a voltage regulator connected to the power supply input;

a current sensor connected to the power supply input, wherein the current sensor is configured to provide a sensed output based on the input voltage;

a microcontroller including a digital output, wherein the microcontroller receives the input voltage via the voltage regulator and provides an output signal via the digital output, wherein the microcontroller stores the first current level and the second current level, and wherein the provided output signal is based on the input voltage and the stored first current level or is based on the input voltage and the stored second current level;

a resistor network connected between the voltage regulator and the microcontroller, wherein the resistor network converts the output signal of the microcontroller into a distinct voltage level;

an operational amplifier, wherein the operational amplifier has a positive input, a negative input, and an output, wherein the positive input is configured to receive the distinct voltage level from the resistor network, wherein the negative input is configured to receive the sensed output from the current sensor, and wherein the output is configured to provide a amplifier output;

a pass transistor connected to the output of the operational amplifier, wherein the pass transistor has a variable impedance based on the amplifier output from the output of the operational amplifier; and

a power supply output configured to provide an output at the first current level or the second current level;

wherein the amplifier output decreases when the sensed output is greater than the first current level, increasing the impedance of the pass transistor and reducing the output to the second current level, and wherein the amplifier output increases when the sensed output is less than the second current level, decreasing the impedance of the pass transistor and increasing the output to the first current level.

2. The system of claim 1, wherein the first change event is a decrease in an impedance associated with a device in the plurality of devices, and wherein the second change event is an increase in an impedance associated with the device in the plurality of devices.

3. The system of claim 1, wherein the first change event is an increase in current drawn by a device in the plurality of devices, and wherein the second change event is a decrease in the current drawn by the device in the plurality of devices.

4. The system of claim 1, wherein the first change event is a rate of increase in current drawn by the device in the plurality of devices, and wherein the second change event is a rate of decrease in current drawn by the device in the plurality of devices.

5. The system of claim 1, wherein the power supply is configured to supply power to the plurality of devices via the system bus at the first current level during a quiet period and at the second current level during a communication period, wherein the communication period corresponds to the first change event and the quiet period corresponds to the second change event.

6. The system of claim 1, wherein the second current level is less than the first current level.

7. The system of claim 1, further comprising:

a control device connected to the system bus, wherein the control device is configured to monitor communications on the system bus that originate or terminate with a device in the plurality of devices, and in response, to provide an indicator instruction to the power supply, wherein the indicator instruction identifies a current level for the power supply to supply power at; and

wherein the power supply is further configured to, upon receipt of the indicator instruction, supply power to the plurality of devices at the current level identified by the indicator instruction.

8. The system of claim 7, wherein the control device is configured to provide the indicator instruction to the power supply prior to the power supply detecting a change event.

9. The system of claim 7, wherein the control device is connected to the system bus via the power supply, and wherein the control device is configured to interpret a current waveform to monitor communications on the system bus that originate or terminate with a device in the plurality of devices, and in response, to provide an indicator instruction to the power supply, wherein the indicator instructions identifies a current level for the power supply to supply power at.

10. The system of claim 9, wherein the control device is configured to digitally process a current waveform to determine a possible bit sequence of a communication on the system bus that originates or terminates with a device in the plurality of devices, and in response, to provide an indicator instruction to the power supply, wherein the indicator instruction identifies a current level for the power supply to supply power at.

11. The system of claim 9, wherein the control device is configured to determine a possible bit sequence such that the control device is configured to assign a probability to each increase and decrease in current, wherein the probability corresponds to a chance of the increase being a positive transition or a negative transition in the current or to a chance of the decrease being a positive transition or a negative transition in the current, to calculate a collective probability of successive transitions to identify at least two candidate bit sequences, and to select as the possible bit sequence the candidate bit sequence having the highest calculated collective probability.

12. The system of claim 7, wherein the plurality of devices are each configured to communicate asynchronously via the system bus, and wherein the control device is further configured to arbitrate communication between the plurality of devices via the system bus.

13. The system of claim 1, wherein at least one device in the plurality of devices comprises an input stage comprising a rectifier and an energy storage device, wherein the energy storage device is charged by voltage from the power supply and the rectifier helps prevent discharge of the energy storage device through the system bus.

14. The system of claim 1, wherein a device in the plurality of devices is configured to control an amount of current drawn by the device.

15. The system of claim 14, wherein the amount of current drawn by the device is determined based on the current level supplied by the power supply via the system bus.

16. The system of claim 14, wherein the device is configured to detect a communication associated with another device in the plurality of devices, and the amount of current drawn by the device is determined based on the detected communication.

17. A power supply, comprising:

a power supply input configured to receive an input voltage;

a voltage regulator connected to the power supply input;

a current sensor connected to the power supply input, wherein the current sensor is configured to provide a sensed output based on the input voltage;

a microcontroller including a digital output, wherein the microcontroller receives the input voltage via the voltage regulator and provides an output signal via the digital output, wherein the microcontroller stores a first current level and a second current level, and wherein the provided output signal is based on the input voltage and the stored first current level or is based on the input voltage and the stored second current level;

a resistor network connected between the voltage regulator and the microcontroller, wherein the resistor network converts the output signal of the microcontroller into a distinct voltage level;

an operational amplifier, wherein the operational amplifier has a positive input, a negative input, and an output, wherein the positive input is configured to receive the distinct voltage level from the resistor network, wherein the negative input is configured to receive the sensed output from the current sensor, and wherein the output is configured to provide a amplifier output;

a pass transistor connected to the output of the operational amplifier, wherein the pass transistor has a variable impedance based on the amplifier output from the output of the operational amplifier; and

a power supply output configured to provide an output at the first current level or the second current level;

wherein the amplifier output decreases when the sensed output is greater than the first current level, increasing the impedance of the pass transistor and reducing the output to the second current level, and wherein the amplifier output increases when the sensed output is less than the second current level, decreasing the impedance of the pass transistor and increasing the output to the first current level.

18. The power supply of claim 17, further comprising:

a communication detector, wherein the communication detector includes a high-pass filter and a comparator;

a voltage feedback; and

a current feedback;

wherein the communication detector, the voltage feedback, and the current feedback provide, respectively, a first input signal, a second input signal, and a third input signal to the microcontroller;

wherein the communication detector is configured to detect communication between a plurality of devices connected to the power supply via a system bus and to provide the first input signal to the microcontroller based on the detected communication; and

wherein the microcontroller is configured to provide the output signal via the digital output based on the first input signal, the second input signal, and the third input signal.