Battery charger having a multiple function sense line

• US 5,589,756 A
• Filed: 11/29/1994
• Issued: 12/31/1996
• Est. Priority Date: 11/29/1994
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Wilson, Nathaniel B., McLaren, Elbert A. II
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): SHIN, KYUNG E
• Application Number:
  US08/346,960
• Time in Patent Office: 763 Days
• Field of Search: 320/21-24, 320/27-29, 320/39, 320/5
• US Class Current: 320/150
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence

Abstract

The battery charging system of the present invention charges the battery (105) of a portable, multiple mode radiotelephone (110) while the radiotelephone is operating. The radiotelephone (110) generates a clock signal having varying on/off times dependent on the radiotelephone'"'"'s mode. This mode can include an analog cellular mode or a digital cellular mode. The battery charger (100) detects the clock signal'"'"'s on/off times and changes the average charge current to compensate for one mode requiring a larger charge current. The clock signal is coupled to the charger using the same multiple function connection (160) as the battery'"'"'s thermistor (150). The charger (100) uses the thermistor (150) to determine when the battery (105) is charged.

Claims

1. A battery charging system having at least a first and a second charging mode, the system charging a battery in a battery powered device having at least a first and a second operating mode, the battery charging system comprising:

a battery charger for charging the battery;

a clock signal generator coupled to the battery charger by a multiple function conductor, the clock signal generator impressing a first clock signal on said multiple function conductor during the first operating mode and impressing a second clock signal on said multiple function conductor during the second operating mode;

a temperature sensing device, coupled to the multiple function conductor, for sensing a temperature of the battery;

a clock detection circuit, coupled to the multiple function conductor, for detecting the first clock signal and the second clock signal;

a temperature detection circuit, coupled to the multiple function conductor, for detecting the temperature of the battery over said multiple function conductor in response to the temperature sensing device; and

a variable current source for generating a first current in the first charging mode when the first clock signal is detected and a second current in the second charging mode when the second clock signal is detected.

4. The battery charging system of claim 1 further comprising:

a switch, coupled to said multiple function conductor and said clock signal generator and interposed therebetween, for selectively applying said first and second clock signals to said multiple function conductor in response to said operating mode of said battery powered device.

2. A battery charging system having at least a high output mode and a low output mode, the system charging a battery in a battery powered radiotelephone having a digital cellular operating mode and an analog cellular operating mode, the battery charging system comprising:

a battery charger for charging the battery;

a clock signal generator coupled to the battery charger by a multiple function conductor, the clock signal generator impressing a first clock signal on said multiple function conductor during the analog cellular operating mode and impressing a second clock signal on said multiple function conductor during the digital cellular operating mode;

a thermistor, coupled to the multiple function conductor, for sensing a temperature of the battery;

a clock detection circuit, coupled to the multiple function conductor, for detecting the first clock signal and the second clock signal;

a temperature detection circuit, coupled to the multiple function conductor, for detecting the temperature of the battery over said multiple function conductor in response to the thermistor; and

a variable current source for generating a first current in the high output mode when the first clock signal is detected and a second current in the low output mode when the second clock signal is detected, the first current being larger than the second current.

3. A battery charging system having an average charge current, the system charging a battery in a battery powered radiotelephone having a digital cellular operating mode and an analog cellular operating mode, the system also supplying power to the radiotelephone, the battery charging system comprising:

a battery charger for charging the battery;

a clock signal generator in the battery powered radiotelephone, said battery powered radiotelephone coupled to the battery charger over a multiple function connection, the clock signal generator generating a clock signal having varying on and off times over said multiple function connection in response to the digital cellular operating mode and the analog cellular operating mode;

a clock detection circuit in the battery charger for detecting the varying on and off times, the clock detection circuit coupled to the multiple function connection;

a thermistor coupled to the multiple function connection, the thermistor having a resistance rate of change responsive to a temperature of the battery;

a resistance detection circuit in the battery charger for detecting the resistance rate of change of the thermistor over said multiple function connector, the resistance detection circuit coupled to the multiple function connection;

a first current source for generating a first current; and

a second current source for generating a second current, the first and second current sources together generating the average charge current in response to the varying on and off times.

5. A method for charging a battery in a battery charging system having at least a first and a second charging mode, the system charging a battery in a battery powered device having at least a first and a second operating mode, the method comprising the steps of:

generating, in the battery powered device, a first clock signal during the first operating mode and a second clock signal during the second operating mode;

impressing said first clock signal on a multiple function conductor during the first operating mode and impressing said second clock signal on said multiple function conductor during the second operating mode;

sensing a temperature of the battery;

detecting the first clock signal and the second clock signal;

detecting the temperature of the battery over said multiple function conductor in response to the temperature sensing device; and

generating a first current in the first charging mode when the first clock signal is detected and a second current in the second charging mode when the second clock signal is detected.

6. A method for charging a battery in a battery charging system having at least a high output mode and a low output mode, the system charging a battery in a battery powered radiotelephone having a digital cellular operating mode and an analog cellular operating mode, the method comprising the steps of:

generating, in the battery powered radiotelephone, a first clock signal during the analog cellular operating mode and a second clock signal during the digital cellular operating mode;

impressing said first clock signal on a multiple function conductor during the analog cellular operating mode and impressing a second clock signal on said multiple function conductor during the digital cellular operating mode;

sensing a temperature of the battery;

detecting the first clock signal and the second clock signal;

detecting the temperature of the battery over said multiple function conductor in response to the thermistor; and

generating a first current in the high output mode when the first clock signal is detected and a second current in the low output mode when the second clock signal is detected, the first current being larger than the second current.

7. A method for charging a battery in a battery charging system having an average charge current, the system charging a battery in a battery powered radiotelephone having a digital cellular operating mode and an analog cellular operating mode, the system also supplying power to the radiotelephone, the method comprising the steps of:

generating, in the battery powered radiotelephone, a clock signal having varying on and off times over a multiple function connection in response to the digital cellular operating mode and the analog cellular operating mode;

detecting the varying on and off times;

sensing the temperature of the battery;

detecting the temperature of the battery over said multiple function conductor in response to the thermistor; and

generating the average charge current in response to the varying on and off times.