Current balancing for voltage regulator having inputs from multiple power supplies

• US 6,177,783 B1
• Filed: 09/13/1999
• Issued: 01/23/2001
• Est. Priority Date: 09/13/1999
• Status: Expired due to Term

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: ADC Telecommunications Incorporated (TE Connectivity Limited)
• Inventors: Donohue, John E.
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Vu, Bao Q.
• Application Number:
  US09/394,149
• Time in Patent Office: 498 Days
• Field of Search: 323/272, 323/282, 323/269, 363/65, 363/78, 363/79
• US Class Current: 323/272
• CPC Class Codes: G05F 1/565 sensing a condition of the system or its load in addition to means responsive to deviations in the output of the system, e.g. current, voltage, power factor G05F1/563 takes precedence
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit
• CPC Class Codes: H02J 1/001 Hot plugging or unplugging of load or power modules to or from power distribution networks
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence

Abstract

A voltage regulator is provided. The voltage regulator comprises a first voltage-controlled current regulator having a first power input and at least one additional voltage-controlled current regulator having at least one other power input. The first and the at least one additional voltage-controlled current regulators have first and second current paths, respectively, and a common output node. The voltage regulator also includes an error amplifier that is responsive to the common output node. The error amplifier further has an output. The output of the error amplifier provides a common feedback signal to the first and the at least one additional voltage-controlled current regulators so as to establish selected currents drawn by the first and the at least one other power inputs and provided to the common output node.

Claims

1. A voltage regulator, comprising:

a first voltage-controlled current regulator having a first power input adapted to be coupled to a first power supply;

at least one additional voltage-controlled current regulator having at least one other power input adapted to be coupled to at least one other power supply;

the first and the at least one additional voltage-controlled current regulators having first and second current paths, respectively, and a common output node;

a common error amplifier, responsive to the common output node, and having an output; and

wherein the output of the error amplifier provides a common feedback signal to the first and the at least one additional voltage-controlled current regulators so as to establish selected currents for the first and the at least one additional voltage-controlled current regulators.

2. The voltage regulator of claim 1, wherein the at least one additional voltage-controlled current regulator comprises one additional voltage-controlled current regulators.

3. The voltage regulator of claim 1, wherein the first voltage-controlled current regulator includes:

a current sense resistor;

a transistor;

wherein the current sense resistor and the transistor are coupled in series between the first power input and the common output node; and

wherein a gate of the transistor is responsive to the feedback signal from the error amplifier and the voltage drop across the current sense resistor so as to control the current passed by the transistor between the first power input and the common output node.

4. The voltage regulator of claim 3, wherein the first voltage-controlled current regulator further includes:

a differential amplifier that senses the current drop on the current sense resistor; and

an operational amplifier, responsive to the differential amplifier and the feedback control signal, and providing a control signal to the gate of the transistor.

5. The voltage regulator of claim 1, wherein the first and the at least one additional voltage-controlled current regulators include first and second transistors coupled in the first and second current paths, respectively, and controlled by the common feedback signal from the error amplifier.

6. The voltage regulator of claim 5, wherein the first and the at least one additional voltage-controlled current regulators include first and second protection diodes coupled in series with the first and second transistors, respectively, so as to prevent current from flowing out the first and at least one other power inputs.

7. The voltage regulator of claim 1, wherein the first and second voltage-controlled current regulators provide substantially the same current to the common output node.

8. The voltage regulator of claim 1, and further including a soft-start circuit that is coupled to the output of the error amplifier so as to control the rate at which the feedback signal changes at start-up, power-on or under external control.

9. The voltage regulator of claim 8, wherein the soft-start circuit includes a last make pin that initiates a ramp-up of the voltage on the feedback signal.

10. The voltage regulator of claim 8, wherein the soft-start circuit includes:

an operational amplifier with a first input coupled to a reference voltage and a second input coupled to an RC circuit with at least one resistor coupled to a last make pin; and

a capacitor coupled to the output of the operational amplifier and to the output of the error amplifier.

11. The voltage regulator of claim 10, and further including a diode coupled between the capacitor and the output of the error amplifier to isolate the soft-start circuit when the voltage on the capacitor reaches a selected level.

12. A circuit pack, comprising:

a number of functional signal inputs and outputs;

a functional circuit responsive to the functional signal inputs and providing signals to the functional signal outputs;

a first power input;

at least one additional power inputs; and

a voltage regulator responsive to the first power input and the at least one additional power input, wherein the voltage regulator provides power with balanced current draw from the first and at least one additional power inputs to the functional circuit, the voltage regulator comprising;

a first voltage-controlled current regulator responsive to the first power input adapted to be coupled to a first power supply;

at least one additional voltage-controlled current regulator responsive to the at least one additional power input adapted to be coupled to at least one other power supply;

the first and the at least one additional voltage-controlled current regulators having first and second current paths, respectively, and a common output node;

a common error amplifier, responsive to the common output node, and having an output; and

wherein the output of the error amplifier provides a common feedback signal to the first and the at least one additional voltage-controlled current regulators so as to establish selected currents in the first and at least one additional voltage-controlled current regulators.

13. The circuit pack of claim 12, wherein the at least one additional voltagecontrolled current regulator comprises one additional voltage-controlled current regulators.

14. The circuit pack of claim 12, wherein the first voltage-controlled current regulator includes:

a current sense resistor;

a transistor;

wherein the current sense resistor and the transistor are coupled in series between the first power input and the common output node; and

wherein a gate of the transistor is responsive to the feedback signal from the error amplifier and the voltage drop across the current sense resistor so as to control the current passed by the transistor between the first power input and the common output node.

15. The circuit pack of claim 14, wherein the first voltage-controlled current regulator further includes:

a differential amplifier that senses the current drop on the current sense resistor; and

an operational amplifier, responsive to the differential amplifier and the feedback control signal, and providing a control signal to the gate of the transistor.

16. The circuit pack of claim 12, wherein the first and the at least one additional voltage-controlled current regulators include first and second transistors coupled in the first and second current paths, respectively, and controlled by the common feedback signal from the error amplifier.

17. The circuit pack of claim 16, wherein the first and the at least one additional voltage-controlled current regulators include first and second protection diodes coupled in series with the first and second transistors, respectively, so as to prevent current from flowing out the first and at least one other power inputs.

18. The circuit pack of claim 12, wherein the first and second voltage-controlled current regulators provide substantially the same current to the common output node.

19. The circuit pack of claim 12, and further including a soft-start circuit that is coupled to the output of the error amplifier so as to control the rate at which the feedback signal changes at start-up, power-on or under external control.

20. The circuit pack of claim 19, wherein the soft-start circuit includes a last make pin that initiates a ramp-up of the voltage on the feedback signal.

21. The circuit pack of claim 19, wherein the soft-start circuit includes:

an operational amplifier with a first input coupled to a reference voltage and a second input coupled to an RC circuit with at least one resistor coupled to a last make pin; and

a capacitor coupled to the output of the operational amplifier and to the output of the error amplifier.

22. The circuit pack of claim 21, and further including a diode coupled between the capacitor and the output of the error amplifier to isolate the soft-start circuit when the voltage on the capacitor reaches a selected level.

23. A method for balancing current draw from a plurality of power inputs, the method comprising:

sensing the current for a first power input, adapted to be coupled to a first power supply, in a first voltage-controlled current regulator;

sensing the current for at least one additional power input, adapted to be coupled to at least one additional power supply, in at least one additional voltage-controlled current regulator;

monitoring the voltage at a common node for the first and at least one additional voltage-controlled current regulator;

generating a current command signal based on the monitored voltage at the common node; and

providing the current command signal to the first and the additional voltage-controlled current regulators to control the current for each power input based on the current command signal and the sensed current.

24. The method of claim 23, wherein sensing the current for the first power input comprises sensing the voltage drop across a resistor in a current path.

25. The method of claim 23, wherein generating a current command signal comprises generating a current command signal with a common voltage error amplifier.

26. The method of claim 23, and further comprising establishing the current in the first voltage-controlled current regulator using a transistor in a current path of the first voltage-controlled current regulator.

27. The method of claim 23, and further comprising controlling the current command signal with a soft-start circuit.

28. A voltage regulator, comprising:

a plurality of feedback-controlled current paths, each responsive to a power supply input;

the current paths coupled together at a common output node;

a common error amplifier coupled to the common node that compares the voltage at the node with a selected voltage and that generates a control signal for the feedback-controlled current paths such that the common node provides a regulated output voltage with selected current for each of the current paths.

29. The voltage regulator of claim 28, wherein the plurality of feedback-controlled current paths include a plurality of voltage-controlled current regulators.

30. The voltage regulator of claim 29, wherein each voltage-controlled current regulator includes:

a current sense resistor;

a transistor;

wherein the current sense resistor and the transistor are coupled in series between one of the power supply inputs and the common output node; and

wherein a gate of the transistor is responsive to the control signal from the error amplifier and the voltage drop across the current sense resistor so as to control the current passed by the transistor between the one of the power supply inputs and the common output node.

31. The voltage regulator of claim 28, wherein each of the plurality of feedback controlled current paths provide substantially the same current to the common output node.

32. The voltage regulator of claim 28, and further including a soft-start circuit that is coupled to the output of the error amplifier so as to control the rate at which the control signal changes at start-up, power-on or under external control.

33. The voltage regulator of claim 32, wherein the soft-start circuit includes a last make pin that initiates a ramp-up of the voltage on the control signal.

34. The voltage regulator of claim 32, wherein the soft-start circuit includes:

an operational amplifier with a first input coupled to a reference voltage and a second input coupled to an RC circuit with at least one resistor coupled to a last make pin; and

a capacitor coupled to the output of the operational amplifier and to the output of the error amplifier.