DC to DC controller with inrush current protection

• US 20040080891A1
• Filed: 05/08/2003
• Published: 04/29/2004
• Est. Priority Date: 10/24/2002
• Status: Active Grant

• Current Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Original Assignee: O2 Micro International Limited (O2 Micro Incorporated)
• Inventors: Shyr, You-Yuh, Bucur, Constantin, Popescu-Stanesti, Vlad
• Granted Patent: US 7,203,048 B2
• Time in Patent Office: Days
• US Class Current: 361/93.1
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

A DC to DC controller for controlling an inrush current from a DC to DC converter to a battery system having an internal isolating switch. The DC to DC controller is configured to control the DC to DC converter based on a state of the internal isolating switch. If the switch is open, the DC to DC controller adjusts the output voltage of the DC to DC converter to a predetermined voltage level. Based on the value of such voltage level, in rush current from the DC to DC converter to the battery system can be reduced or eliminated when the isolating switch changes from an open state to a closed state. An electronic device including such a DC to DC controller is provided. Related methods for controlling inrush current are also provided.

Claims

1. A DC to DC controller for controlling an inrush current from a DC to DC converter to a battery system having an internal isolating switch, said DC to DC controller comprising:

a first path configured to accept a first input signal representative of an output power level of said DC to DC converter, said first path configured to provide a first control signal;

a second path configured to accept said first input signal, said second path configured to provide a second control signal if said internal isolating switch is in an open state; and

a regulating circuit configured to accept said first and second control signals and to regulate said output power level to a first level if controlled by said first control signal and to regulate said output power parameter to a second level if controlled by said second control signal.

2. The DC to DC controller of claim 1, wherein said output power level is an output voltage level and said first level is a first output voltage level and said second level is a second output voltage level.

3. The DC to DC controller of claim 2, wherein said battery system comprises a battery having a minimum battery voltage level, and wherein said second output voltage level is within a predetermined range of said minimum battery voltage level for preventing said inrush current from exceeding a predetermined acceptable inrush current level when said internal isolating switch changes from said open state to a closed state.

4. The DC to DC controller of claim 2, wherein said battery system comprises a battery having a minimum battery voltage level, and wherein said second output voltage level is less than or equal to said minimum battery voltage level to eliminate said inrush current when said internal isolating switch changes from said open state to a closed state.

5. The DC to DC controller of claim 1, further comprising a switch state detection circuit configured to detect a state of said internal isolating switch and provide a switch state control signal representative of a state of said internal isolating switch to said second path.

6. The DC to DC controller of claim 5, wherein said output power level is an output voltage level of said DC to DC converter and wherein said switch state detection circuit comprises a first comparator configured to compare a first comparison signal representative of said output voltage level of said DC to DC converter with a second comparison signal representative of a predetermined maximum voltage level of said DC to DC converter, said switch state detection circuit providing said switch state control signal representative of said open state of said internal isolating switch if said first comparison signal is greater than said second comparison signal.

7. The DC to DC controller of claim 1, wherein said output power level is an output voltage level of said DC to DC converter and said second level is a second output voltage level, and wherein said second path further comprises a comparator configured to accept a first comparison signal representative of said output voltage level of said DC to DC converter and a second comparison signal representative of said second output voltage level to drive said output voltage level to said second voltage level if said internal isolating switch is in said open state.

8. The DC to DC controller of claim 1, wherein said regulating circuit comprises a pulse width modulation (PWM) circuit configured to provide a PWM control signal.

9. An electronic device comprising:

a battery system comprising a rechargeable battery and an internal isolating battery switch coupled to said rechargeable battery;

a DC to DC converter configured to accept an input power level from a DC power source and provide an output power level to said battery system for recharging said rechargeable battery; and

a DC to DC controller for controlling an inrush current from said DC to DC converter to said battery system, said DC to DC controller comprising;

a first path configured to accept a first input signal representative of said output power level, said first path configured to provide a first control signal;

a second path configured to accept said first input signal and provide a second control signal if said internal isolating battery switch is in an open state; and

a regulating circuit configured to accept said first and second control signals and to regulate said output power level to a first level if controlled by said first control signal and to regulate said output power level to a second level if controlled by said second control signal.

10. The electronic device of claim 9, wherein said output power level is an output voltage level and said first level is a first output voltage level and said second level is a second output voltage level.

11. The electronic device of claim 10, wherein said rechargeable battery has a minimum battery voltage level, wherein said second output voltage level is within a predetermined range of said minimum battery voltage level for preventing said inrush current from exceeding a predetermined acceptable inrush current level when said internal isolating battery switch changes from said open state to a closed state.

12. The electronic device of claim 10, wherein said rechargeable battery has a minimum battery voltage level, wherein said second output voltage level is less than or equal to said minimum battery voltage level to eliminate said inrush current when said internal isolating battery switch changes from said open state to a closed state.

13. The electronic device of claim 9, wherein said DC to DC controller further comprises a switch state detection circuit configured to detect a state of said internal isolating battery switch and provide a switch state control signal representative of a state of said internal isolating battery switch to said second path.

14. The electronic device of claim 13, wherein said output power level is an output voltage level of said DC to DC converter and wherein said switch state detection circuit comprises a first comparator configured to compare a first comparison signal representative of said output voltage level of said DC to DC converter with a second comparison signal representative of a predetermined maximum voltage level of said DC to DC converter, said switch state detection circuit providing said switch state control signal representative of said open state if said first comparison signal is greater than said second comparison signal.

15. The electronic device of claim 9, wherein said output power parameter is an output voltage level of said DC to DC converter and said second level is a second output voltage level, and wherein said second path further comprises a comparator configured to accept a first comparison signal representative of said output voltage level of said DC to DC converter and a second comparison signal representative of said second output voltage level to drive said output voltage level to said second voltage level if said internal isolating battery switch is in said open state.

16. An electronic device comprising

a battery system comprising a rechargeable battery and an internal battery switch coupled to said rechargeable battery;

a DC to DC converter configured to accept an input power level from a DC power source and provide an output power level to said battery system for recharging said rechargeable battery; and

a DC to DC controller configured to control said DC to DC converter based on a state of said internal battery switch.

17. The electronic device of claim 16, wherein said DC to DC controller provides a switch open control signal to said DC to DC converter when said internal switch is open, wherein said DC to DC converter is responsive to said switch open control signal to provide a predetermined output voltage level at an output of said DC to DC converter.

18. The electronic device of claim 16, wherein said predetermined output voltage level is within a predetermined range of a minimum voltage level of said rechargeable battery such that an inrush current to said rechargeable battery from said DC to DC converter is controlled when said internal battery switch changes from an open to a closed state.

19. The electronic device of 16, wherein said predetermined output voltage level is equal to or less than a minimum voltage level of said rechargeable battery such that an inrush current to said rechargeable battery from said DC to DC converter is eliminated when said internal battery switch changes from an open to a closed state.

20. A method of controlling inrush current from a DC to DC converter to a battery system having an internal battery isolating switch, said method comprising:

detecting a state of said internal battery isolating switch; and

adjusting an output voltage level of said DC to DC converter to a predetermined output voltage level if said state of said internal battery switch is an open state.

21. The method of claim 20, wherein said predetermined output voltage level is within a predetermined range of a minimum voltage level of a rechargeable battery of said battery system such that an inrush current to said rechargeable battery from said DC to DC converter is controlled when said internal battery switch changes from said open state to a closed state.

22. The method of 20, wherein said predetermined output voltage level is equal to or less than a minimum voltage level of a rechargeable battery of said battery system such that an inrush current to said rechargeable battery from said DC to DC converter is eliminated when said internal battery switch changes from said open state to a closed state.