Power-saving mode for portable communication devices

• US 20010018356A1
• Filed: 01/10/2001
• Published: 08/30/2001
• Est. Priority Date: 04/24/1998
• Status: Active Grant

• Current Assignee: David A. Cathey, David A. Zimlich, Kipp A. Bedard
• Original Assignee: David A. Cathey, David A. Zimlich, Kipp A. Bedard
• Inventors: Cathey, David A., Zimlich, David A., Bedard, Kipp A.
• Granted Patent: US 6,532,375 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H04B 1/3805 with built-in auxiliary receivers
• 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: H04W 88/02 Terminal devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Method and apparatus for ensuring that, in a portable, battery-powered communication package incorporating at least two communication devices, such as a combination cellular telephone and a pager, sufficient power is provided for extended operation of the communication device having the lowest continuous power consumption requirements when the device having a higher continuous power consumption rate has consumed a selected portion of the total power initially available to the combined devices. In the case of the aforestated exemplary device, cellular telephone function is disabled when a selected portion of the total power initially available is consumed. A first embodiment of the invention is implemented with a single electrochemical battery. The first embodiment of the invention may include a headroom-limited flyback power supply which powers the high-power consumption device. When headroom drops below a minimum set by a series-coupled diode string, power is cut off to the high-power-consumption device. The first embodiment of the invention may alternatively include a battery charge sense circuit which produces a digital signal, the digital signal corresponding to either a battery charge state that is above the predetermined voltage level or a battery charge state that is below the predetermined voltage level. For this alternate first embodiment, operation of the high-power-consumption device is disabled when the predetermined battery charge state is reached, thus permitting operation of the low-power consumption communication device for an extended period which, ideally, should be at least 24 hours. A second embodiment of the invention is implemented using a separate electrochemical power source (e.g., a single electrochemical cell or battery) to power the low-power consumption device.

Claims

1. A portable communication package comprising:

a first battery-powered communication device and a second battery-powered communication device, said second communication device having power consumption requirements which are at least an order of magnitude greater than those of the first communication device;

at least one battery supplying a flow of electricity for powering both communication devices, said at least one battery having first and second output terminals, said first output terminal having a potential that is positive with respect to the potential of said second output terminal;

a power management unit for providing an uninterrupted flow of electricity to said first communication device for a predetermined period although said battery has insufficient capacity for providing an uninterrupted flow of electricity to said second communication device for said predetermined period, said power management unit comprising;

an oscillator having a clock signal;

an inverter including a P-channel FET having a gate coupled to said clock signal and a channel coupling said first output terminal to an output node, and an N-channel FET having a gate coupled to said clock signal and a channel coupling said second output terminal to said output node;

a current-limiting resistor;

an intermediate FET having a gate and a channel connected in series with said current-limiting resistor coupling said first output terminal to said second output terminal;

a plurality of series-coupled diodes coupling said output node to the gate of said intermediate FET; and

a flyback inductor through for current from a storage device to intermittently flow, such intermittent flow being controlled by said intermediate FET to provide a pulsating flyback voltage after the rectification and filtering thereof gives an output voltage for powering said second communication device.

2. The portable communication package of

claim 1

, wherein said at least one single battery includes a first battery and second battery which together constitute a supply of electricity, said first battery providing power to said first communication device, and said second battery providing power to said second communication device.

3. The portable communication package of

claim 2

, wherein said first battery comprises an electrochemical cell and said second battery comprises a battery of a plurality of electrochemical cells.

4. The portable communication package of

claim 1

, wherein said power management unit includes:

a reference voltage;

a measured voltage representative of a charge level of said battery;

a switch for cutting the flow of electricity from said storage device to said second battery-powered communication device when the measured voltage drops below a predetermined level that corresponds to a minimum battery charge level required for continued operation of the first battery-powered communication device for a desired period of time.

5. The portable communication package of

claim 4

, wherein a silicon bandgap circuit produces said reference voltage.

6. The portable communication package of

claim 4

, wherein a voltage divider circuit produces said measured voltage.

7. The portable communication package of

claim 4

, which further comprises a comparator including:

an output;

a first input coupled to said reference voltage; and

a second input coupled to said measured voltage.

8. The portable communication package of

claim 4

, wherein said switch is a transistor controlled by said comparator output.

9. The portable communication package of

claim 4

, wherein said first communication device is a pager, and said second communication device is a wireless telephone.

10. The portable communication package of

claim 1

, which further comprises:

an intermediate node interposed between said current-limiting resistor and said intermediate FET;

a final FET having a gate coupled to said intermediate node through at least one buffer, said final FET and said flyback inductor providing a serial current path between said first and second output terminals; and

a final node within the serial current path interposed between said flyback inductor and said final FET, said intermittent power output taken from said final node within the serial current path.

11. The portable communication package of

claim 1

, wherein said intermediate FET and said final FET are both N-channel devices.

12. The portable communication package of

claim 11

, further comprising:

an adjustment resistor interposed in the serial current path having a resistance value setting the output voltage.

13. The portable communication package of

claim 1

, further comprising:

a flyback shut-off transistor controlled by said output voltage for disabling said inverter when said output voltage reaches a preset level.

14. The portable communication package of

claim 13

, further comprising:

a voltage divider which adjusts said preset level.

15. In combination with at least two communication devices packaged in a single portable unit having a single battery providing power for operating said devices, a power management unit comprising:

an oscillator producing a clock signal;

an inverter including a P-channel FET having a gate coupled to said clock signal and a channel coupling a first output terminal to an output node, and an N-channel FET having a gate coupled to said clock signal and a channel coupling a second output terminal to said output node;

a current-limiting resistor;

an intermediate FET having a gate and a channel in series with said current-limiting resistor coupling a first output terminal to a second output terminal;

a plurality of series-coupled diodes coupling said output node to the gate of said intermediate FET;

a flyback inductor through which current from a storage device intermittently flows being controlled by said intermediate FET for providing intermittent output power subsequent to rectification and filtering powers a second communication device;

an intermediate node interposed between a current-limiting resistor and an intermediate FET;

a final FET having a gate coupled to said intermediate node through at least one buffer, said final FET and said flyback inductor providing a serial current path between said first and second output terminals; and

a final node within the serial current path, said final node interposed between said flyback inductor and said final FET for said intermittent output power being taken from the final node.

16. The combination of

claim 15

, wherein said intermediate FET and said final FET are both N-channel devices.

17. The combination of

claim 15

, wherein said power management unit further comprises:

an adjustment resistor interposed in the serial current path having a resistance value setting an output voltage.

18. In combination with a wireless communication device and a pager device packaged in a single portable unit having a single battery providing power for operating both of said devices, a power management unit comprising:

an oscillator producing a clock signal;

an inverter having both a P-channel FET having a gate coupled to said clock signal and a channel coupling a first output terminal to an output node and an N-channel FET having a gate coupled to said clock signal and a channel coupling a second output terminal to said output node;

a current-limiting resistor;

an intermediate FET having a gate and a channel connected in series with said current-limiting resistor coupling a first output terminal to a second output terminal;

a plurality of series-coupled diodes coupling said output node to the gate of said intermediate FET; and

a flyback inductor through which current from a storage device intermittently flows being controlled by said intermediate FET to provide intermittent output power subsequent to the rectification and filtering thereof powers said second communication device.

19. The combination of

claim 18

, wherein said power management unit further comprises:

an intermediate node interposed between said current-limiting resistor and said intermediate FET; and

a final FET having a gate coupled to said intermediate node through at least one buffer, said final FET and said flyback inductor providing a serial current path between said first and second output terminals, said intermittent output power being taken from a final node within the serial current path, said final node interposed between said flyback inductor and said final FET.

20. The combination of

claim 19

, wherein said intermediate FET and said final FET are both N-channel devices.