Method and apparatus for operating a mobile communication device coupled with an external power supply for charging a battery of the mobile communication device

• US 20070149254A1
• Filed: 12/28/2005
• Published: 06/28/2007
• Est. Priority Date: 12/28/2005
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Inventors: Patino, Joseph, Ballantyne, Wayne, Tassi, Scott, Carrero, Alfredo
• Granted Patent: US 7,742,753 B2
• Time in Patent Office: Days
• US Class Current: 455/573
• CPC Class Codes: H04W 52/0277 according to available power supply, e.g. switching off when a low battery condition is detected
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A mobile communication device 100 has a digital subsystem (110) and a radio frequency subsystem (108), and is powered by a battery (102) which is charged via a charge control circuit (106) using an external power supply (104) connected to the mobile communication device in a single path configuration. The mobile communication device permits limited operation of the mobile communication device by a user while the battery voltage is sufficient to power the digital subsystem but not yet sufficient to power the radio frequency subsystem. The delay in operation is minimized, however, because once charging commences, the battery voltage rises sufficiently fast that, typically, by the time the digital subsystem is initialized, enabled, and powered up, the battery voltage will be sufficient to enable the radio frequency subsystem.

Claims

1. A mobile communication device, comprising:

a battery having a battery voltage;

a charge control circuit for charging the battery from an external power source;

a digital subsystem powered by the battery voltage and enabled for operation only while the battery voltage is above a first level; and

a radio frequency subsystem powered by the battery voltage and enabled for operation only while the battery voltage is above a second level;

wherein the second level is higher than the first level.

2. A mobile communication device as defined in claim 1, wherein the digital subsystem is enabled by a comparator circuit comparing the battery voltage with a reference voltage equal to the first level.

3. A mobile communication device as defined in claim 1, wherein the radio frequency subsystem is enabled by a comparator circuit comparing the battery voltage with a reference voltage equal to the second level.

4. A mobile communication device as defined in claim 1, further comprising an oscillator coupled to the digital subsystem and radio frequency subsystem for providing a clock signal to the digital subsystem and radio frequency subsystem;

a first voltage regulator for supplying a first regulated voltage to the oscillator when the battery voltage is above the first level and below the second level; and

a second voltage regulator for supplying a second regulated voltage to the oscillator when the battery voltage is above the second level;

wherein the second regulated voltage level is above the first regulated voltage level.

5. A mobile communication device as defined in claim 4, wherein the oscillator is a temperature compensated crystal oscillator.

6. A mobile communication device as defined in claim 1, wherein the digital subsystem operates a user interface for allowing a user to operate the mobile communication device when the battery voltage is above the first level and below the second level.

7. A mobile communication device as defined in claim 1, wherein, if the battery voltage is below the first level, the charger circuit commences charging the battery and continues to charge to the battery to a battery voltage above the second level.

8. A method of operating a mobile communication device while charging a battery of the mobile communication device, the battery having a battery voltage, comprising:

connecting an external power source to the mobile communication device;

charging the battery from the external power;

while the battery voltage is below a first level, maintaining a digital subsystem and a radio frequency subsystem of the mobile communication device in an unenabled state;

while the battery voltage is above the first level and below a second level, enabling the digital subsystem and maintaining the radio frequency subsystem in the unenabled state; and

while the battery voltage is above the second level enabling both the digital and radio frequency subsystems;

wherein the digital and radio frequency subsystems are both powered by the battery voltage.

9. A method of operating a mobile communication device as defined in claim 8, further comprising:

while the battery voltage is above the first level and below the second level, applying a first regulated voltage to an oscillator providing a clock signal to the digital and radio frequency subsystems; and

while the battery voltage is above the second level, applying a second regulated voltage to the oscillator;

wherein the second regulated voltage level is above the first regulated voltage.

10. A method of operating a mobile communication device as defined in claim 9, wherein the oscillator is a temperature compensated crystal oscillator.

11. A method of operating a mobile communication device as defined in claim 8, wherein the mobile communication device is initially in an off state, the method further comprising:

receiving a user input to turn the mobile communication device on;

providing a user interface by the digital subsystem while the battery voltage is between the first and second levels; and

allowing operation of the radio frequency subsystem when the battery voltage is above the second level.

12. A method of operating a mobile communication device having a battery, the battery having a battery voltage, an external power supply initially coupled to the mobile communication device for charging the battery, the method comprising:

disconnecting the external power source from the mobile communication device;

if the battery voltage is above an upper level, maintaining both a digital subsystem in a powered up state and a radio frequency subsystem in a powered up state;

if the battery voltage falls below the upper level, maintaining the digital subsystem in the powered up state and disabling the radio frequency subsystem; and

if the battery voltage falls below a lower level, disabling both the digital subsystem and radio frequency subsystem.

13. A method of operating a mobile communication device as defined in claim 12, further comprising:

while the battery voltage is above upper level, applying an upper regulated voltage to an oscillator providing a clock signal to the digital and radio frequency subsystems; and

while the battery voltage is below the upper level, applying a lower regulated voltage to the oscillator.

14. A method of operating a mobile communication device as defined in claim 13, wherein the oscillator is a temperature compensated crystal oscillator.

15. A method of operating a mobile communication device as defined in claim 12, wherein when the battery voltage is between the upper and lower levels, the method further comprising maintaining a user interface provided by the digital subsystem.

16. A method of operating a mobile communication device as defined in claim 12, further comprising shutting off the digital subsystem if the battery voltage falls below the lower level.