System and method for automatically enabling rapid charging of a battery in a portable phone

• US 5,764,035 A
• Filed: 09/23/1996
• Issued: 06/09/1998
• Est. Priority Date: 09/23/1996
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Ericsson, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Lee, Tina May
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): SHIN, KYUNG E
• Application Number:
  US08/717,675
• Time in Patent Office: 624 Days
• Field of Search: 320/160, 320/161, 320/162, 320/163, 320/164, 320/165
• US Class Current: 320/160
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

A system and method for automatically enabling rapid charging of a battery in a portable phone when a battery charger is connected to the portable phone is disclosed. The system includes a battery charger circuit having an input for receiving an input voltage from the battery charger, a sense resistor through which a rapid charging current from the battery charger input voltage is generated, a charge switch connected to the sense resistor which receives the battery charger circuit input, a trickle resistor connected in parallel to the charge switch through which a slow charging current from the battery charger input voltage is generated, wherein the rapid charging current is generated when the charge switch is closed and the trickle charging current is generated when the charge switch is open, and an output for supplying the generated charging current to the battery. The system also includes at least one voltage regulator having an input connected to the battery and an output for supplying a voltage to circuitry of the portable phone for controlling the battery charger circuit, as well as a circuit for selectively enabling the voltage regulator depending on the battery voltage. In this system, the rapid charging current may be supplied to the battery from the battery charging circuit only when the voltage regulator is enabled.

Claims

1. A system for automatically enabling rapid charging of a battery in a portable phone, when a battery charger is connected to said portable phone, comprising:

(a) a battery charger circuit, further comprising;

(1) an input for receiving an input voltage from said battery charger;

(2) means for generating a rapid charging current from said battery charger input voltage;

(3) means for generating a trickle charging current from said battery charger input voltage;

(4) means for selecting one of said rapid charging current and said trickle charging current; and

(5) an output for supplying the selected charging current to said battery;

(b) at least one voltage regulator having an input connected to said battery and an output for supplying a voltage to circuitry of said portable phone for controlling said battery charger circuit; and

(c) means for selectively enabling said voltage regulator;

wherein said rapid charging current may be supplied to said battery from said batter charging circuit only when said voltage regulator is enabled.

2. The system of claim 1, said battery charger circuit further comprising:

(a) a charge switch connected to said battery charger circuit input;

(b) a trickle resistor connected in parallel to said charge switch; and

(c) a sense resistor connected in series with said charge switch and said trickle resistor;

wherein said rapid charging current is generated when said charge switch is closed and said trickle charging current is generated when said charge switch is open.

3. The system of claim 2, said battery charger circuit further comprising a control for opening and closing said charge switch.

4. The system of claim 3, wherein said control maintains said charge switch open when voltage of said battery is greater than a specified amount.

5. The system of claim 3, wherein said control permits said charge switch to be closed when voltage of said battery is less than a specified amount.

6. The system of claim 1, said enabling means providing a control signal to enable said voltage regulator when said battery charger input voltage is greater than voltage of said battery by a specified amount.

7. The system of claim 6, said enabling means comprising a transistor which receives said battery charger input voltage at an emitter region, receives said battery voltage at a base region, and provides said control signal from a collector region.

8. The system of claim 1, further comprising means for preventing said enabling means from enabling said voltage regulator when voltage of said battery is less than a designated amount.

9. The system of claim 7, further comprising a low voltage detector having an input which receives said battery voltage and an output connected to said transistor collector region, wherein said low voltage detector prevents said control signal from enabling said voltage regulator when said battery voltage is less than a designated amount and permits said control signal to enable said voltage regulator when said battery voltage is greater than said designated amount.

10. The system of claim 9, wherein said designated amount is equivalent to a release threshold voltage of said low voltage detector.

11. The system of claim 9, said low voltage detector including an integral delay, wherein a specified time period elapses between when said low voltage detector input receives a battery voltage greater than said designated amount and said low voltage detector output actually permits said control signal to enable said voltage regulator.

12. The system of claim 9, further comprising a filter located between said battery voltage and said low voltage detector input, wherein said filter provides a specified time delay between when a battery voltage greater than said designated amount is produced and said low voltage detector input actually receives it to permit said control signal to enable said voltage regulator.

13. The system of claim 1, further comprising means for automatically powering-off said portable phone when said battery is removed therefrom.

14. A method of automatically powering-on a portable phone when a battery charger is connected to said portable phone, comprising the following steps:

(a) providing a voltage from a battery to an input of at least one voltage regulator in said portable phone;

(b) providing an input from said batter charger to a battery charger circuit in said portable phone;

(c) continuously sensing said battery voltage;

(d) generating a control signal when said battery charger input voltage is greater than said battery voltage by a specified amount;

(e) enabling said voltage regulator connected to said battery charger circuit; and

(f) powering-on circuitry of said portable phone for controlling said battery charger circuit with an output voltage from said voltage regulator.

15. The method of claim 14, further comprising the step of preventing said voltage regulator from being enabled by said control signal if said battery voltage is less than a designated amount.

16. The method of claim 15, further comprising the following steps:

(a) trickle charging said battery; and

(b) permitting said control signal to enable said voltage regulator once said battery voltage is greater than said designated amount.

17. The method of claim 16;

further comprising the step of delaying the enabling of said voltage regulator by said control signal for a specified time period after said battery voltage is greater than said designated amount.

18. The method of claim 14, further comprising the step of rapidly charging said battery in accordance with signals sent to said battery charger circuit from said control circuitry.

19. The method of claim 18, wherein said control circuitry permits said battery to be rapidly charged when said battery voltage is less than a certain amount.

20. The method of claim 18, wherein said control circuitry permits said battery to be rapidly charged when said battery voltage is greater than a certain amount.

21. The method of claim 14, wherein said control signal must be provided to said voltage regulator for a specified time period to enable said voltage regulator.

22. The method of claim 14, further comprising the step of maintaining said portable phone in a powered-on state until said battery charger is disconnected from said battery.

23. The method of claim 14, further comprising the step of automatically powering-off said portable phone when said battery is removed therefrom.

24. A method of automatically enabling rapid charging of a battery in a portable phone when a battery charger is connected to said portable phone, comprising the following steps:

(a) providing a voltage from a battery to an input of at least one voltage regulator in said portable phone;

(b) providing an input voltage from said battery charger to a battery charger circuit in said portable phone;

(c) continuously sensing said battery voltage;

(d) generating a control signal when said battery charger input voltage is greater than said battery voltage by a specified amount;

(e) enabling said voltage regulator connected to said battery charger circuit;

(f) powering-on circuitry of said portable phone for controlling said battery charger circuit with an output voltage from said voltage regulator; and

(g) rapidly charging said battery in accordance with signals sent from said control circuitry to said battery charger circuit.