BATTERY CHARGE SYSTEM WITH TRANSITION CONTROL THAT PROTECTS ADAPTER COMPONENTS WHEN TRANSITIONING FROM BATTERY MODE TO ADAPTER MODE

• US 20150280473A1
• Filed: 07/21/2014
• Published: 10/01/2015
• Est. Priority Date: 03/26/2014
• Status: Active Grant

• Current Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Original Assignee: Intersil Americas LLC (Renesas Electronics Corporation)
• Inventors: ZHAO, LEI, WEI, JIA, KLEINE, JOHN S.
• Granted Patent: US 10,797,490 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: H02J 1/082 Plural DC voltage, e.g. DC supply voltage with at least two different DC voltage levels
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence

Abstract

A battery charge system including an adapter node, a system node, a battery, a first isolation switch coupled between the adapter and system nodes, a second isolation switch coupled between the battery and system nodes, a boost converter, and a controller. The controller turns off the first isolation switch and turns on the second isolation switch during a battery mode, activates the boost converter when an adapter voltage is detected, turns off the second isolation switch when the system voltage rises above the battery voltage, and turns on the first isolation switch when the system voltage rises to an operating voltage level. The boost converter may then be turned off once in the adapter mode. The second isolation switch may initially be turned on partially at a low current level when the adapter is detected, and then turned fully on when the system voltage is at the operating voltage level.

Claims

1. A battery charge system, comprising:

an adapter node and a system node;

a battery;

a first isolation switch coupled between said adapter node and said system node;

a second isolation switch coupled between said battery and said system node;

a boost converter operative to boost a battery voltage of said battery to increase a system voltage on said system node when activated; and

a controller that turns off said first isolation switch and that turns on said second isolation switch during a battery mode, that activates said boost converter when an adapter voltage is detected on said adapter node, that turns off said second isolation switch when said system voltage rises above said battery voltage, and that turns on said first isolation switch when said system voltage rises to a predetermined operating voltage level.

2. The battery charge system of claim 1, wherein said controller turns off said second isolation switch when said system voltage is greater than said battery voltage by a first offset voltage, and wherein said controller turns on said first isolation switch when said system voltage is within a second offset voltage of a detect voltage indicative of said adapter voltage.

3. The battery charge system of claim 1, wherein said controller deactivates said boost converter after said first isolation switch is turned on.

4. The battery charge system of claim 1, wherein switching of said boost converter is controlled based on said system voltage compared with said detect voltage.

5. The battery charge system of claim 1, wherein said controller further turns on said first isolation switch at a low current level before activating said boost converter, and then fully turns on said first isolation switch when said system voltage reaches said predetermined operating voltage level.

6. The battery charge system of claim 5, wherein said boost converter is controlled to regulate said first isolation switch to maintain said low current level.

7. The battery charge system of claim 1, wherein said boost converter is controlled with open loop control at a constant duty cycle.

8. The battery charge system of claim 1, wherein said controller comprises:

a first comparator that compares a detect voltage indicative of said adapter voltage with a threshold voltage and that provides an adapter detect signal indicative thereof;

a second comparator that compares said system voltage with said battery voltage and that provides a boost signal indicative thereof;

a third comparator that compares said system voltage with said detect voltage and that provides an adapter transition signal indicative thereof;

a modulator for operating said boost converter; and

a transition controller that receives said adapter detect signal, said boost signal, and said adapter transition signal and that provides a first control signal to control said first isolation switch, a second control signal to control said second isolation switch, and a third control signal to said modulator to control activation of said boost converter.

9. The battery charge system of claim 8, further comprising an amplifier that receives said system voltage and said detect voltage and that provides an error signal to said modulator.

10. The battery charge system of claim 8, further comprising:

a current sensing system that detects current from said adapter node to said system node and that provides a current sense signal indicative thereof; and

an amplifier that receives said current sense signal and a reference signal and that provides an error signal to said modulator.

11. A controller for a battery charge system, comprising:

an adapter voltage sense input, a system voltage sense input, and a battery voltage sense input;

a first isolation switch output and a second isolation switch output;

a modulator system having a boost control output;

a comparator system that compares a voltage of said adapter voltage sense input with a threshold voltage and that provides an adapter detect signal indicative thereof, that compares a voltage of system voltage sense input with a voltage of said battery voltage sense input and that provides a battery off signal indicative thereof, and that compares said voltage of system voltage sense input with said voltage of said adapter voltage sense input and that provides an adapter transition signal indicative thereof; and

a transition controller that is operative to place said first isolation switch output in an off state and to place said second isolation switch output in an on state when said adapter detect signal indicates a battery mode, to activate said modulator in a boost mode in response to transition of said adapter detect signal, to place said second isolation switch output in an off state in response to transition of said battery off signal, and to place said first isolation switch output in an on state in response to transition of said adapter transition signal.

12. The controller of claim 11, wherein said comparator system transitions said adapter detect signal when said voltage of said adapter voltage sense input rises above a predetermined voltage threshold, wherein said comparator system transitions said battery off signal when said voltage of system voltage sense input is greater than said voltage of said battery voltage sense input by a first offset voltage, and wherein said comparator system transitions said adapter transition signal when said voltage of system voltage sense input is within a second offset voltage of said voltage of said adapter voltage sense input.

13. The controller of claim 11, wherein said transition controller is further configured to deactivate said modulator from boost mode after said first isolation switch output is placed in an on state.

14. The controller of claim 11, wherein said modulator operates with open loop control and constant duty cycle while in said boost mode.

15. The controller of claim 11, further comprising:

an amplifier that receives said voltage of system voltage sense input and said voltage of said adapter voltage sense input and that provides an error signal indicative thereof; and

wherein said modulator modulates based on said error signal while in said boost mode.

16. The controller of claim 11, further comprising:

a current sense input coupled to a current sense device for providing a current sense signal indicative of an adapter current level;

an amplifier that receives said current sense signal and a current reference value and that provides an error signal indicative thereof; and

wherein said modulator modulates based on said error signal while in said boost mode.

17. The controller of claim 16, wherein said transition controller is further operative to place said first isolation switch output in a partially on state in response to said transition of said adapter detect signal while in said battery mode, and then to place said first isolation switch output in a fully on state in response to said transition of said adapter transition signal.

18. A method of controlling a battery charge system, comprising:

operating in a battery mode including isolating an adapter node from a system node when an AC adapter is not detected at the adapter node;

activating a boost converter mode to boost a battery voltage of a battery to increase a system voltage on the system node when the AC adapter is detected in the adapter node;

isolating the battery from the system node when a system voltage of the system node rises above the battery voltage; and

coupling the adapter node to the system node when the system voltage reaches a predetermined operating voltage level.

19. The method of claim 18, further comprising:

partially coupling the adapter node to the system node at a low current level when the AC adapter is initially detected; and

fully coupling the adapter node to the system node when the system voltage reaches the predetermined operating voltage level.

20. The method of claim 18, further comprising:

monitoring a current level between the adapter node and the system node and providing a current sense signal indicative thereof; and

controlling the boost converter mode based on the current sense signal.

21. The method of claim 18, further comprising deactivating the boost converter mode when the system voltage reaches the predetermined operating voltage level.