Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
2001-09-07
2002-10-22
Tso, Edward H. (Department: 2888)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
Reexamination Certificate
active
06469474
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to cache cards and, more particularly, to a battery gauge for use in a cache card.
2. Description of the Related Art
As the power of individual electronic computing devices has increased, computing systems have become more distributed. Early “personal” computers, although powerful for their time, were suitable for little more than primitive word processing, spreadsheet, and video game applications More intensive applications, e.g., computer aided design/computer aided manufacturing (“CAD/CAM”) applications were typically hosted on relatively large, more powerful “mainframe” computers. Users invoked applications from time-sharing terminals that served as a conduit for information. However, most of the computational power resided on the host mainframe, where most of the computations were performed.
Stand-alone computing devices eventually evolved from dumb terminals and weak personal computers to powerful personal computers and workstations. As they became more powerful, the computational hours for applications became more distributed. Individual computers eventually became networked, and the networks distributed the computational activities among the network members. Many computations once performed on a mainframe computer, or that were not previously performed, were now performed on networked personal computers. Networks also permitted users to share certain types of computing resources, such as printers and storage.
More powerful computing devices also permitted larger, more complex networks and other computing systems. Small local area networks (“LANs”) became wide area networks (“WANs”). Recently, networks have evolved to produce system or storage area networks (“SANs”). Some of these networks are public, e.g., the Internet. Some may be characterized as “enterprise computing systems” because, although very large, they restrict access to members of a single enterprise or other people they may authorize. Some enterprise computing systems are referred to as “intranets” because they employ the same communication protocols as the Internet.
FIG. 1
illustrates some concepts associated with large scale computing systems such as SANs. The computing system
100
includes two servers
105
,
110
that include a Redundant Array of Independent Disks (“RAID”) controller
115
, a Fibre Host Bus Adapter (“HBA”)
120
, and at least one internal disk
125
. Each RAID controller is connected to the internal disk
125
and an external storage enclosure
130
, also commonly referred to as Just a Bunch Of Disks (“JBOD”). The RAID controller
115
, internal disk
125
, and JBOD
130
constitute “direct attached storage” subsystem. The direct attached storage subsystem is “local” to the respective servers
105
,
110
in the sense that other servers cannot read from or write to it. The Fibre HBA
120
connected to a switch or hub
135
in a switched Fibre fabric
140
. The servers
150
,
110
can both read from and write to the mass storage units
145
through their respective Fibre HBA
120
and the switch/hub
135
in the switched fabric
140
. Thus, the Fibre HBAs
120
, switched fabric
140
, switch/hub
135
, and mass storage units
145
constitute a “shared” memory subsystem.
Most types of electronic and computing systems comprise many different devices that electronically communicate with each other over one or more buses. Exemplary types of devices include, but are not limited to, processors (e.g., microprocessors, digital signal processors, and micro-controllers), memory devices (e.g., hard disk drives, floppy disk drives, and optical disk drives), and peripheral devices (e.g., keyboards, monitors, mice). When electrically connected to a bus, these types of devices, as well as others not listed, are all sometimes generically referred to as “bus devices.” In
FIG. 1
, the RAID controllers
115
communicate the buses
150
,
155
, respectively. The Fibre HBA
120
communicates with switched Fabric
140
and mass storage units
145
over buses
160
,
165
, respectively.
For instance, a computer typically includes one or more printed circuit boards having multiple integrated circuit components (or “bus devices”) and connectors mounted to them. The components and connectors are interconnected by and communicate with each other over trace etched into the board. The boards are interconnected by plugging one or more of the boards into another board intended for this purpose. A first component on a board communicates with a second component on the same board over the traces etched onto the board. The first component communicates with a component on another board through the connectors by which the two boards are plugged into the third board intended for that purpose. Thus, both the traces on the boards and the connectors between the boards are a part of the bus. Again referring to
FIG. 1
, the RAID controllers
115
and Fibre HBAs
120
are two such printed circuit boards.
DIMMs are one common type of memory component. A DIMM is simply a printed circuit board (“PCB”) on which a number of memory chips are mounted. The memory chips are usually some form of “volatile” memory, which means that the data stored in them will be lost if power supplied to the chips is interrupted. Many DIMMs therefore include battery packs mounted to them. The battery packs house batteries that provide “backup” power to the DIMM if the primary source of power is interrupted for some reason. The backup power supplied by the battery packs then provides an opportunity to save the data if primary power is restored in time.
DIMMs are widely used in mass storage devices such as redundant arrays of inexpensive disks (“RAIDs”). DIMMs are sometimes used in a RAID controller to implement a type of memory known as “cache,” and DIMMs used in this context are therefore sometimes referred to as “cache cards.” RAID controllers will only allow posted writes to occur when it can guarantee that the batteries can sustain backup for a minimum period of time agreed upon by the user in the event of a power outage.
One problem frequently encountered in these environments is dead batteries for DIMMs. The useable life of a battery is finite-typically about three years. RAID controllers will only allow posted writes to occur when it can guarantee that the batteries can sustain backup for a minimum period of time agreed upon by the user in the event of a power outage. Each battery type requires a separate technique used to estimate the amount of capacity left. Conventional fuel gauge circuits require resistors in series with the flow of current. These resistors consume power, take up board space, and require an additional ADC circuit to interpret the results. Some battery types such as NiMH have a constant voltage from 100% down to 15% capacity, which makes the terminal voltage technique useless. Typically, the industry has measured the amount of capacity remaining in a battery by measuring the current entering and leaving the battery over time. Alternatively, the amount of capacity remaining in a battery has been measured by measuring the voltage level across the battery terminals only with certain types of battery chemistries. Still further, some approaches measure the amount of capacity remaining in a battery by dropping a resistive load across the battery terminals in an effort to measure the internal battery resistance only with certain types of battery chemistries. Each of these approaches has disadvantages.
The present invention is directed to resolving, or at least reducing, one or all of the problems mentioned above.
SUMMARY OF THE INVENTION
In one aspect, the invention is a battery fuel gauge for a cache card comprising a charging circuit for charging at least one battery and a decrementor circuit for counting the amount of time system power is removed from the battery.
REFERENCES:
patent: 4595880 (1986-06-01), Patil
patent: 5315228 (1994-05-01), Hess et al.
patent: 5883497 (1999-03-01), Turnbull
patent: 6252511 (2001-06-01), Mondshine et al.
patent
Compaq Information Technologies Group L.P.
Conley & Rose & Tayon P.C.
Tso Edward H.
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