Power switch for external module adapted to interface with a portable information handling system

• US 20020180277A1
• Filed: 05/29/2001
• Published: 12/05/2002
• Est. Priority Date: 05/29/2001
• Status: Active Grant

• Current Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Original Assignee: Harman International Industries Incorporated (Samsung Electronics Co. Ltd.)
• Inventors: Anand, Cheyyur J., Acharya, Shrikant, Crosbie, John
• Granted Patent: US 6,696,771 B2
• Time in Patent Office: Days
• US Class Current: 307/140
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 1/1632 External expansion units, e.g. docking stations
• CPC Class Codes: G06F 1/1656 Details related to functional adaptations of the enclosure, e.g. to provide protection against EMI, shock, water, or to host detachable peripherals like a mouse or removable expansions units like PCMCIA cards, or to provide access to internal components for maintenance or to removable storage supports like CDs or DVDs, or to mechanically mount accessories mounting of accessories to a computer display G06F1/1607; display hoods G06F1/1603; cooling arrangements for portable computers G06F1/203

Abstract

The application of external power to an external module connected to a portable information handling system enables the card detection signal to be asserted low, thereby allowing the personal digital assistant to detect and activate the external module. When external power is disconnected from the external module, the card detect signals turn off, thereby deactivating the external module and electrically disconnecting the external module from the personal digital assistant. Substantially all of the power for the external module is provided independently from the internal power supply of the portable information handling system.

Claims

1. A power switch for an electronic component adapted to receive power from at least one external source and at least one card detect signal from an external source, comprising a transistor comprising a first terminal, a second terminal and a third terminal, wherein said first terminal is adapted to receive applied voltage from at least one external source, said second terminal is adapted to receive the at least one card detect signal from the external source, and said third terminal is connectable to ground, whereby application of voltage to said first terminal shorts the card detect signal to ground.

2. The power switch of claim 1, further comprising:

a first resistor between said first terminal and the at least one external power source; and

a second resistor between said first terminal and ground.

3. The power switch of claim 2, wherein said transistor has a switching voltage, and wherein said first resistor and said second resistor form a voltage divider such that the voltage delivered to said first terminal of said transistor from the at least one external power source is at least equal to said switching voltage.

4. The power switch of claim 1, wherein said transistor is an N-type field effect transistor, said first terminal is a gate terminal, said second terminal is a source terminal, and said third terminal is a drain terminal.

5. The power switch of claim 1, wherein said transistor is an N-type bipolar transistor, said first terminal is a base terminal, said second terminal is an emitter terminal, and said third terminal is a collector terminal.

6. The power switch of claim 1, wherein said second terminal of said resistor is adapted to receive two card detect signals from the external source.

7. The power switch of claim 1, wherein the electronic component is a card connectable to a module, said module in turn connectable to an information handling system.

8. A module adapted to interface with at least one external power source and with a portable information handling system providing at least one card detect signal, comprising:

a transistor comprising a first terminal, a second terminal and a third terminal, wherein said first terminal is adapted to receive applied voltage from the at least one external power source, said second terminal is adapted to receive the at least one card detect signal from the portable information handling system, and said third terminal is connectable to ground;

a common power terminal connected to said first terminal of said transistor; and

a steering diode comprising an input electrically connected to the at least one external power source and an output electrically connected to said common power terminal, whereby application of voltage to said first terminal via said steering diode shorts the card detect signal to ground.

9. The module of claim 8, further comprising a second steering diode comprising an input electrically connected to a different at least one external power source and an output electrically connected to said common power terminal.

10. The module of claim 9, wherein each external power source connected to said common power terminal has a different voltage level, and wherein the module further comprises a voltage regulator electrically connected to said common power terminal, said voltage regulator adapted to convert said voltage level at said common power terminal to a different voltage.

11. The module of claim 8, further comprising:

a first resistor between said first terminal and said common power terminal; and

a second resistor between said first terminal and ground;

wherein said transistor has a switching voltage, and wherein said first resistor and said second resistor form a voltage divider such that the voltage delivered to said first terminal of said transistor from the at least one external power source is at least equal to said switching voltage

12. The module of claim 8, further comprising a module power switch electrically connected to the portable information handling system, wherein said portable information handling system closes said module power switch upon application of external power to said common power terminal.

13. The module of claim 8, further comprising a connector comprising at least one socket electrically connected to said second terminal of said transistor, wherein the at least one card detect signal is received through said at least one socket.

15. The system of claim 14, wherein said portable information handling system further comprises a detector/controller electrically connected to said at least one contact on said portable information handling system, said detector/controller adapted to monitor the card detect signal.

16. The system of claim 15, wherein said portable information handling system further comprises:

an internal power source; and

a power enable switch electrically connected to said internal power source and to said detector/controller, wherein said detector/controller closes said power enable switch when the card detect signal is shorted to ground, such that power from said internal power source is transmitted to said module.

17. The system of claim 14, wherein said at least one contact on said portable information handling system is a pin, and said at least one contact electrically connected to said second terminal of said transistor is a socket.

18. The system of claim 14, further comprising a second module adapted to interface with at least one external power source and with said first module, said first module providing at least one card detect signal from said portable information handling system to said second module, said second module comprising:

a second transistor comprising a first terminal, a second terminal and a third terminal, wherein said first terminal is adapted to receive applied voltage from the at least one external power source, said second terminal is adapted to receive the at least one card detect signal from the portable information handling system, and said third terminal is connectable to ground;

a second common power terminal connected to said first terminal of said second transistor; and

a second steering diode comprising an input electrically connected to the at least one external power source and an output electrically connected to said second common power terminal, whereby application of voltage to said first terminal via said steering diode shorts the card detect signal to ground.

19. The system of claim 18, wherein said first module further comprises a module detector/controller electrically connected to at least one contact on said first module, said module detector/controller adapted to monitor the card detect signal.

20. The system of claim 18, wherein said first module further comprises a second power enable switch electrically connected to said internal power source of said portable information handling system and to said module detector/controller, wherein said module detector/controller closes said second power enable switch when the card detect signal is shorted to ground, such that power from said internal power source is transmitted to said second module.

21. The system of claim 20, wherein said second module further comprises a second module power switch electrically connected to said first module, wherein said module detector/controller of said first module closes said second module power switch upon application of external power to said second common power terminal.

14. A power switching system connectible to an external power source, comprising:

a portable information handling system comprising at least one contact adapted to carry a card detect signal; and

a first module detachably connected to said portable information handling system, said first module comprising

a transistor comprising a first terminal, a second terminal and a third terminal, wherein said first terminal is adapted to receive applied voltage from the at least one external power source, said second terminal is adapted to receive the at least one card detect signal from the portable information handling system, and said third terminal is connectable to ground, wherein said transistor has a switching voltage;

at least one contact electrically connected to said second terminal of said transistor, said at least one contact adapted to interface with said at least one contact of said portable information handling system;

a first resistor between said first terminal and the at least one external power source; and

a second resistor between said first terminal and ground, such that voltage delivered to said first terminal of said transistor from the at least one external power source is at least equal to said switching voltage.

22. A method for switching power provided to a module having a transistor comprising a first terminal, a second terminal and a third terminal, the first terminal adapted to receive applied voltage from at least one external source and the third terminal connected to ground, the transistor having a switching voltage, the module adapted to connect to a portable information handling system, the method comprising:

connecting the module to the portable information handling system;

applying a card detect signal to the second terminal of the transistor;

applying external power to the first terminal of the transistor, the external power having a voltage at least equal to the switching voltage of the transistor;

switching on the transistor in response to said applying external power, such that said card detect signal is shorted to ground;

detecting in the portable information handling system that said card detect signal is shorted to ground; and

activating the module.

23. The method of claim 22, further comprising:

ceasing application of external power to the first terminal of the transistor;

switching off the transistor in response to said ceasing, such that said card detect signal is no longer shorted to ground;

detecting in the portable information handling system that said card detect signal is no longer shorted to ground; and

deactivating the module.