Low current DC-DC converter with integrated low current Coulomb counter

• US 9,134,744 B2
• Filed: 01/04/2013
• Issued: 09/15/2015
• Est. Priority Date: 01/04/2013
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Linear Technology Corporation (Analog Devices, Inc.)
• Inventors: Nork, Samuel H.
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): Mehari, Yemane
• Application Number:
  US13/734,485
• Publication Number:
  US 20140191741A1
• Time in Patent Office: 984 Days
• Field of Search: 323/222, 323/223, 323/232, 323/299, 323/301
• US Class Current: 1/1
• CPC Class Codes: G01R 29/24 Arrangements for measuring quantities of charge
• CPC Class Codes: G05F 1/62 using bucking or boosting dc sources
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/1582 Buck-boost converters H02M3/1584 takes precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power supply system includes a regulator circuit responsive to an input signal at the input node for producing an output signal at the output node at a desired level. The regulator circuit has a controller, an inductive element and a first switch coupled to the inductor element and controlled by the controller to produce the output signal. Also, the power supply system includes a Coulomb counter for producing a Coulomb count signal proportional to the number of Coulombs passing from the input node to the output node. The Coulomb counter is enabled by an enabling signal representing a predetermined time period, for determining the number of Coulombs passing from the input node to the output node during that predetermined time period.

Claims

1. A power supply system having an input node and an output node, comprising:

a regulator circuit responsive to an input signal at the input node for producing an output signal at the output node at a desired level, and having a controller, an inductive element and a first switch coupled to the inductor element and controlled by the controller to produce the output signal, and

a Coulomb counter for producing a Coulomb count signal proportional to the number of Coulombs passing from the input node to the output node, the Coulomb counter being enabled by an enabling signal representing a predetermined time period, for determining the number of Coulombs passing from the input node to the output node during the predetermined time period.

2. The system of claim 1, wherein the enabling signal represents a time period during which the first switch is ON.

3. The system of claim 2, wherein the regulator circuit is configured to operate in a buck-boost mode.

4. The system of claim 2, wherein the regulator circuit is configured to operate in a buck mode.

5. The system of claim 1, wherein the regulator circuit is configured to operate in a boost mode and includes a second switch coupled to the inductor element.

6. The system of claim 5, wherein the enabling signal represents the sum of a first time period during which the first switch is ON and a second time period during which the second switch is ON.

7. The system of claim 1, wherein the Coulomb counter is configured for counting the number of Coulombs transferred to the output node from a battery coupled to the input node.

8. The system of claim 1, wherein the Coulomb counter is configured for counting the number of Coulombs transferred from the input node to a battery coupled to the output node.

9. The system of claim 2, wherein the Coulomb counter is enabled for determining the number of Coulombs during only one ON time period of the first switch out of a predetermined number of successive ON time periods of the first switch.

10. The system of claim 1, wherein the regulator circuit is configured for operating in a sleep mode when the output voltage is above a predetermined regulation point.

11. The system of claim 10, wherein circuitry for determining the number of Coulombs is disabled when the regulator circuit is in a sleep mode.

12. The system of claim 1, wherein the Coulomb counter includes a Coulomb measuring circuit for determining the number of Coulombs passing from the input node to the output node during the predetermined time period to produce a value representing the determined number of Coulombs, and a result accumulating circuit for accumulating values produced by the Coulomb measuring circuit.

13. The system of claim 12, wherein an accumulated value in the result accumulating circuit represents total number of periods during which the first switch is ON.

14. The system of claim 1, wherein the regulator circuit and the Coulomb counter are integrated on a single integrated circuit.

15. A method of supplying power from an input node to an output node, comprising the steps of:

in response to an input signal at the input node, producing an output signal at an output node at a desired level,

determining the number of Coulombs passing from the input node to the output node only during a predetermined time period to produce a measurement value representing the number of Coulombs per the predetermined time period, and

accumulating measurement values determined during a number of predetermined time periods to produce a Coulomb count signal representing the total number of Coulombs transferred from the input node to the output node.

16. The method of claim 15, wherein the output signal is produced by a regulator circuit having a first controllable switch, and the predetermined period represents an ON time period of the first controllable switch.

17. The method of claim 16, wherein the number of Coulombs is determined during only one ON time period of the first controllable switch out of a predetermined number of successive ON time periods of the first controllable switch.

18. The method of claim 15, wherein the output signal is produced by a regulator circuit having first and second controllable switches, and the predetermined period represents the sum of an ON time period of the first controllable switch and an ON time period of the second controllable switch.