Power unit and power source switching apparatus for a computer

• US 20010054878A1
• Filed: 03/22/2001
• Published: 12/27/2001
• Est. Priority Date: 03/22/2000
• Status: Active Grant

• Current Assignee: Lenovo PC International Limited (Lenovo Group Ltd.)
• Original Assignee: International Business Machines Corporation
• Inventors: Odaohhara, Shigefumi
• Granted Patent: US 6,396,243 B2
• Time in Patent Office: Days
• US Class Current: 320/118
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0025 Sequential battery discharge in systems with a plurality of batteries

Abstract

In a removable power supply unit for a computer, a power source switching FET provided in a protective circuit of a main battery and a second battery is enabled in response to a signal from the computer to switch power paths from each of the main battery and the second battery to a DC-DC converter of the computer, thereby reducing the number of such power source switching FETs provided in an internal circuit of the computer.

Claims

1. A power unit, including:

a battery enabled to supply power to an external device when connected thereto;

a switch enabled to control switching between supply and shut-off of said power to said external device; and

a switch controller means for controlling said switch in response to a signal from said external device.

2. The power unit according to

claim 1

,

wherein said switch is a field effect transistor (FET).

3. The power unit according to

claim 1

, further including a protection circuit comprising a pair of FETs, wherein one of said pair of FETs functions as said switch in response to said signal from said external device.

4. A power source switching apparatus including:

a plurality of power units, each power unit including a battery enabled to supply power to a load, and a switch enabled to switch between supply and shut-off of said power to said load, said power source switching apparatus further including;

a switch controller operable to selectively signal each of said power units to actuate said switch.

5. The power source switching apparatus according to

claim 4

, further including:

a plurality of internal switches enabled to switch between supply and shut-off of said power;

said switch controller being operable to control switching between an internal switch and said power unit switch so as to prevent a short-circuit between the batteries of said power units whilst changing the battery that supplies said power to said load.

6. The power source switching apparatus according to

claim 5

;

wherein said switch controller is operable to shut off both of said internal switch and said power unit switch in case of problems with either said internal switch or said power unit switch

7. The power source switching apparatus according to

claim 5

, wherein said internal switches and said power unit switches are field effect transistors (FET) disposed in the same power path so that internal diodes in the switches are connected to each other at the same polarity.

8. A computer including:

a load;

a plurality of power units, each including;

a battery enabled to supply power to said load; and

a switch enabled to switch between supply and shut-off of said power to said load;

the computer further including;

a switch controller operable to selectively signal each of said power units to actuate said switch.

9. The computer according to

claim 8

, further including a protection circuit in each of said plurality of power units, each protection circuit comprising a pair of FETs, one of said pair of FETs being arranged to function as said switch in response to signals from said switch controller.

10. A power source switching apparatus for selectively supplying power to a load from an external power source and a plurality of batteries, comprising:

an external power circuit for supplying power received from said external power source to said load;

a charging circuit for charging at least one of said plurality of batteries with the power received from said external power circuit;

a plurality of serial circuits, each being provided in a power path between each of said plurality of batteries and said load and being configured by two switches connected serially, each of said two switches being configured so that diodes disposed in parallel in the switches are connected to each other at the same polarity terminal respectively; and

a switching circuit provided in each charge path between said charging circuit and each of said plurality of batteries and configured so that a switch in said charge path is connected to a junction point between said two switches in a corresponding serial circuit and diodes disposed in parallel in said charge path switch are connected to said diodes in said two switches at the same polarity terminal respectively.

11. The power source switching apparatus according to

claim 10

;

wherein both of said two switches in each power path and said switch in each charge path are field effect transistors (FET).

12. A computer including:

a load;

a plurality of batteries;

an external power circuit for supplying power received from said external power source to said load;

a charging circuit for charging at least one of said plurality of batteries with the power received from said external power circuit;

a plurality of serial circuits, each being provided in a power path between each of said plurality of batteries and said load and being configured by two switches connected serially, each of said two switches being configured so that diodes disposed in parallel in the switches are connected to each other at the same polarity terminal respectively; and

a switching circuit provided in each charge path between said charging circuit and each of said plurality of batteries and configured so that a switch in said charge path is connected to a junction point between said two switches in a corresponding serial circuit and diodes disposed in parallel in said charge path switch are connected to said diodes in said two switches at the same polarity terminal respectively.