Power enabling mechanism, a power enabling method, and a...

Details Power enabling mechanism, a power enabling method, and a... Power enabling mechanism, a power enabling method, and a...

1995-12-12

2003-04-29

Wiley, David (Department: 2158)

Electrical computers and digital processing systems: support

Computer power control

Reexamination Certificate

active

06557106

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a power enabling mechanism, a power enabling method, and an input/output device controller for controlling a supply of power by an information processing apparatus to an input/output device that is attached to it; and in particular, it relates to a power enabling mechanism, a power enabling method, and an input/output device controller for controlling a supply of power to a PC card, which is inserted into the slot of a personal computer (PC) so as to be detachable. More specifically, the present invention pertains to a power enabling mechanism, a power enabling method, and an input/output device controller for securing a supply of power to a PC card that is loaded into a slot of a personal computer and for preventing a voltage decrease and a circuit fault of a PC, and the latch-up of a PC card even when power consumption for a PC card is abnormal (or there is a large consumption of power that exceeds an established standard).
BACKGROUND OF THE INVENTION
Because of recent developments in packaging technique, the use of desktop and laptop (or notebook) personal computers (PCs) has become widespread.
Since a PC is generally compact or portable, the standard hardware resources that can be mounted at the shipping stage are limited. A user can, therefore, assemble his own system by attaching desired input/output devices to ports and/or to connectors in the PC.
A so-called PC card is a specific example of an input/output device for an expandable PC. The physical specifications and the electric specifications for PC cards are established mainly by the PCMCIA (Personal Computer Memory Card International Association) and JEIDA (Japan Electronic Industry Development Association). Although the standards for PC cards were only memory card specifications at the beginning, I/O card specifications were added later, and now various types of cards, such as facsimile modems, SCSIs (Small Computer System Interfaces), hard disks, and LAN (Local Area Network) adaptors, are commercially available. At the present, for most PCs the expansion of hardware resources is ensured by the provision of one or more slots into which these PC cards can be inserted (see FIG.
10
). In addition to PC cards being compact and easy to exchange, PC cards support a function whereby they can be attached to and detached from a PC while it is powered on (the so-called “active insertion and extraction” or “Plug and Play” function), and thus make easier exchange or expansion using PC cards.
FIG. 11
is a diagram illustrating the (conventional) schematic arrangement
100
of hardware by which a PC communicates with a PC card
60
that conforms to the specifications established by PCMCIA/JEIDA. PC card
60
is mechanically loaded into expansion PC slot
50
wherein it is electrically connected, via PCMCIA controller
20
, to input/output bus
10
of the PC. Input/output bus
10
is a common transfer path for the exchange of data by a CPU (not shown) and individual input/output devices, and conforms to, for example, the ISA (Industry Standard Architecture) bus standard.
PCMCIA controller
20
is a controller chip for enabling connection of the PC to PC card
60
. From the point of view of data distribution, PCMCIA controller
20
communicates with input/output bus
10
of the PC via interface
21
, and communicates with the PC card
60
via a driver
25
and a receiver
26
. Interface
21
is connected to an address signal line, a data signal line, and a control signal line of input/output bus
10
(generally, address signals are transmitted in one direction from the PC, and data signals and control signals are transmitted bidirectionally). Through interface
21
, operational timings between the PC and PC card
60
are matched and data expression forms are converted. Driver
25
drives PC card
60
in accordance with the contents carried in a control signal. Driver
25
receives from interface
21
an address signal, a data signal, and a control signal that are transmitted in one direction and driver
25
sends them to PC card
60
. The function of driver
25
can be understood by explaining that driver
25
is an output buffer that transmits an electric signal to PC card
60
. By way of contrast, receiver
26
receives data from PC card
60
and transmits it to interface
21
. Receiver
26
relays data signals that are transmitted in the return direction. Register
23
is a circuit for temporarily storing specific data, and receives part of the address signals and the data signals that are transmitted via the interface
21
. Register
23
includes an address for writing a value that is designated by configuration software of the PC, an address for writing the load state of PC card
60
, and an address for writing an instruction (V
CC
bit and V
PP
bit) for the supply of power to PC card
60
(which will be described later). The PC can access the individual addresses of register
23
during an I/O read cycle.
According to the standards specified by PCMCIA/JEIDA, the PC is so designed that it provides two system power lines
35
and
36
for which the voltage levels, V
CC
and V
PP
, differ according to which PC card
60
is involved. Generally, power line
35
is employed to apply a reference voltage V
CC
(3.3 V or 5 V) that PC card
60
requires for normal operation. Power line
36
is employed to provide voltage V
PP
for an optional upgrade operation (for example, for a PC card that has non-volatile memory, such as flash ROM, may employ voltage V
PP
for erasing data from and the writing data to the non-volatile memory) that requires a comparatively high voltage (or an auxiliary voltage V
CC
). According to the specifications, some PC cards
60
use only V
CC
while others use both V
CC
and V
PP
. PCMCIA controller
20
not only controls the exchange of data between the PC and PC card
60
, but also controls the supply of power by the PC to PC card
60
. More specifically, a power enabler
24
, which is in PCMCIA controller
20
, and a power controller
30
cooperate in the process. Power enabler
24
is provided with the V
CC
bit and the V
PP
bit in register
23
, and enables or disables control signals V
CC
—
En and V
PP
—
En, which are employed to instruct the connection/disconnection of power lines
35
and
36
, in consonance with the setting or clearing of bits. Switches
31
and
32
of power controller
30
are opened or closed, in response to the outputs of V
CC
—
En and V
PP
—
En, to supply or to cut off voltages V
CC
and V
PP
. P-channel MOSFETs or bipolar transistors, for example, may be used for switches
31
and
32
. PCMCIA controller
20
is driven by system voltage V
DD
, which is different than V
CC
and V
PP
.
It is assumed that a PC card (especially, a PC card that conforms to PCMCIA/JEIDA standards) is frequently loaded into and unloaded from a PC, and various PC card types that are produced by many makers are now commercially available. However, almost nothing concerning the consumption of power by PC cards is contained in the current standards that are specified for PC cards. There are PC cards that have a large power consumption that exceeds the power supply capabilities of the PC card power circuits that are provided in the PCs, and there have been some instances where such PC cards have been loaded into the slots of PCs. In another cases, the power sources are short-circuited to the GND (ground) because of the abnormalities of internal circuits of the PC cards. Further, since the present I/O card standards that were specified for PC cards were added to the original standards that were specified for memory cards, cards such as hard disk cards (so-called Type III cards), whose power consumption is large (although neither abnormal nor over current), have been loaded into slots that were intended for memory cards. When the power consumption of a loaded PC card is unexpectedly great, the PC card power supply circuit in the PC and the power circuit of the PC itself may be destroyed, and the data contents of the memory for the PC will be lost.

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