U.S. patent application number 09/773112 was filed with the patent office on 2001-06-28 for battery monitoring system with integrated battery holder.
Invention is credited to Jones, Brian W., Jones, Scott E..
Application Number | 20010005123 09/773112 |
Document ID | / |
Family ID | 23415910 |
Filed Date | 2001-06-28 |
United States Patent
Application |
20010005123 |
Kind Code |
A1 |
Jones, Brian W. ; et
al. |
June 28, 2001 |
Battery monitoring system with integrated battery holder
Abstract
An apparatus for monitoring the condition of a battery. The
apparatus includes a battery clip that is used to secure a battery
to a battery connection and a battery monitoring IC. The battery
monitoring IC takes a "load vs. no-load measurement" and the
results are recorded in a register. When the battery reaches a
certain low voltage state, register bits are set and an output is
generated. Furthermore, the exemplary embodiment includes a removal
detection circuit for detecting removal and replacement of the
battery and for preventing voltage floating on the battery output
line.
Inventors: |
Jones, Brian W.;
(Richardson, TX) ; Jones, Scott E.; (Highland
Village, TX) |
Correspondence
Address: |
Roger L. Maxwell
Jenkens & Gilchrist, A Professional Corporation
Suite 3200
1445 Ross Avenue
Dallas
TX
75202-2799
US
|
Family ID: |
23415910 |
Appl. No.: |
09/773112 |
Filed: |
January 31, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
09773112 |
Jan 31, 2001 |
|
|
|
09359940 |
Jul 22, 1999 |
|
|
|
6208114 |
|
|
|
|
Current U.S.
Class: |
320/107 |
Current CPC
Class: |
G01R 31/3648 20130101;
H01M 10/4257 20130101; H01M 10/48 20130101; H01M 50/216 20210101;
Y10S 320/12 20130101; H01M 50/209 20210101; Y02E 60/10 20130101;
G01R 19/16542 20130101; G01R 31/367 20190101; G01R 31/3647
20190101 |
Class at
Publication: |
320/107 |
International
Class: |
H02J 007/00 |
Claims
What is claimed is:
1. A battery monitoring system for monitoring the state of a
battery, the system comprising: a printed circuit board (PCB); an
electrical contact connected to the PCB, the electrical contact for
electrically coupling with the battery; a battery monitoring
integrated circuit (IC) attached to the PCB, the battery monitoring
IC for determining the state of the battery; and a battery clip
attachable to the PCB, the battery clip, when attached to the PCB,
for securing the battery to the electrical contact.
2. The battery monitoring system of claim 1, wherein the battery
monitoring IC comprises: measurement circuitry for performing a
DELTA-V measurement.
3. The battery monitoring system of claim 2, wherein the battery
monitoring IC further comprises: a storage location for storing the
DELTA-V measurement.
4. The battery monitoring system of claim 3, wherein the battery
monitoring IC further comprises: an interface connected to the
storage location, the DELTA-V measurement stored in the storage
location being accessible through the interface.
5. The battery monitoring system of claim 2, further comprising:
circuitry for signaling a low battery condition.
6. The battery monitoring system of claim 5, further comprising: a
storage device connected to the circuitry; wherein an indicator of
the low battery condition is stored in the storage device.
7. The battery monitoring system of claim 1, wherein the battery
monitoring IC comprises: a battery removal detector for detecting
the removal of the battery from the electrical contact.
8. The battery monitoring system of claim 7, wherein the battery
removal detector limits voltage floating on a battery output line
responsive to the battery being removed from the electrical
contact.
9. The battery monitoring system of claim 1, wherein the battery
clip is configured to secure a coin-shaped primary cell.
10. A battery monitoring circuit comprising: a measurement circuit
element for performing a DELTA-V measurement; a storage device for
storing the DELTA-V measurement; and an interface connected to the
storage location, the DELTA-V measurement stored in the storage
device being accessible through the interface; and a signal circuit
element for signaling a low battery condition responsive to the
DELTA-V measurement.
11. The battery monitoring circuit of claim 10 wherein an indicator
of a low battery is stored in the storage device.
12. The battery monitoring circuit of claim 10, wherein the battery
monitoring IC comprises: a battery removal detector for detecting
removal of the battery.
13. The battery monitoring circuit of claim 12, wherein the battery
removal detector limits voltage float on a battery output line.
14. The battery monitoring circuit of claim 10 further comprising:
a primary cell coupled with the measurement circuit element.
15. A system comprising: a memory device for storing data, the
memory device configured to draw power from a primary power source
and a battery; a battery holder connected to the memory device, the
battery holder for holding the battery; and a controller attached
to the battery holder, the controller for monitoring the condition
of the battery and for generating a low battery indication.
16. The system of claim 15 wherein the controller performs a
DELTA-V measurement.
17. The system of claim 16 further comprising: a storage device
connected to the controller, the storage device for storing the low
battery indication.
18. The system of claim 17 further comprising: a processor
connected to the storage device, the processor for receiving the
low battery indication.
19. The system of claim 18 wherein the low battery indication is
generated prior to battery failure.
20. The system of claim 15 wherein the battery holder is attachable
to a system board.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to battery monitoring
circuitry and more particularly, but not by way of limitation, to a
battery monitoring system that includes an integrated battery
holder.
[0003] 2. Background of the Problem and Related Art
[0004] It is well known that a primary battery is a convenient
source of power for portable electric and electronic devices. Small
size, ease of use, low maintenance and good shelf life are just a
few of the reasons that primary batteries are frequently used in
modern electronics. For example, primary batteries are regularly
used in PCS and servers to keep a time of day clock running even
when the particular device is not otherwise powered.
[0005] Because the primary battery is such a convenient and
reliable source of power, many electronic devices also use the
primary battery as a source of backup power, such as for CMOS
memory--thereby preserving the contents of the memory even when the
memory is not otherwise powered. In fact, the computer and
electronic industry has incorporated the coin-shaped primary
battery into the majority of devices that require a backup power
source.
[0006] Because the primary battery often protects critical data
from corruption and loss, a user cannot allow the battery to fail.
The failure of a primary battery could mean disastrous data
corruption, data loss and/or system downtime--all of which are
unacceptable in today's information critical systems. Accordingly,
it is vital that a user or system administrator be able to easily
and accurately determine when a primary battery is nearing failure
(but not yet completely depleted) and should be replaced.
[0007] Furthermore, it is vital that a primary battery be
replaceable without corrupting the data it is backing up. In
existing devices, replacing a primary cell allows voltage at the
backed-up device to float. For example, FIG. 1 illustrates a block
diagram of a battery backed device 105 connected to a primary
battery 110 through a supply voltage line 115 and a battery output
line 120. The primary battery 110 is also grounded at ground 125.
In this device, when the primary battery 110 is removed or
inserted, the voltage on line battery output 120 momentarily
changes, i.e., floats, and likely creates a condition in the
battery backed device 105 that results in data corruption or other
damage.
[0008] In light of the above-described and other deficiencies in
the existing art, a device is needed that accurately monitors the
characteristics of a battery, particularly the characteristics of a
primary battery used in electronic systems. Furthermore, a device
is needed that prevents the voltage on the primary battery's output
line from floating when the battery is replaced.
SUMMARY OF THE INVENTION
[0009] To remedy the deficiencies of existing systems and methods,
the present invention provides, among other things, an apparatus to
accurately monitor the characteristics of a battery. Furthermore,
the present device prevents the voltage on the primary battery's
output line from floating when the battery is replaced.
[0010] In an exemplary embodiment, but by no means the only
embodiment, the invention includes a battery clip that is used to
secure a battery to a battery connection and a battery monitoring
integrated circuit (IC). The battery monitoring IC takes a "load
vs. no-load measurement" and the results are recorded in a
register. When the battery reaches a certain low voltage state,
register bits are set and a low battery signal is generated.
Furthermore, the exemplary embodiment includes a removal detection
circuit both for detecting removal and replacement of the battery
and for preventing voltage float on the battery output line.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Various objects and advantages and more complete
understanding of the present invention will become apparent and
more readily appreciated by reference to the following Detailed
Description and to the appended claims when taken in conjunction
with the accompanying Drawings wherein:
[0012] FIG. 1 is a block diagram of a battery backed device
connected to a primary battery;
[0013] FIG. 2 is an exploded perspective of a battery holder
including a battery monitoring integrated circuit (IC);
[0014] FIG. 3 is a block diagram of the electronics of the battery
holder shown in FIG. 1;
[0015] FIG. 4 is a "voltage vs. time" plot for a no-load voltage
measurement and a loaded voltage measurement; and
[0016] FIG. 5 is a more detailed block diagram of the battery
monitoring IC shown in FIGS. 2 and 3.
DETAILED DESCRIPTION
[0017] Although the present invention is open to various
modifications and alternative constructions, a preferred exemplary
embodiment that is shown in the drawings is described herein in
detail. It is to be understood, however, that there is no intention
to limit the invention to the particular forms disclosed. One
skilled in the art can recognize that there are numerous
modifications, equivalences and alternative constructions that fall
within the spirit and scope of the invention as expressed in the
claims.
[0018] Referring now to FIG. 2, there is illustrated an exploded
perspective of a battery holder 200 with a battery monitoring
integrated circuit (IC) 225, which can be a microcontroller. In
particular, there is illustrated a battery clip 205 that is
attachable to a printed circuit board (PCB) 210. By attaching the
battery clip 205 to the PCB 210, the battery 215 can be secured
such that the cathode of the battery 215 is in contact with a
metallic contact 220, such as a gold plated contact, located on the
PCB 210. Additionally, pins 230 are also connected to the PCB
210.
[0019] In one embodiment, the battery clip 205 is constructed with
nickel plated spring steel. In this embodiment, the battery clip
205 can be easily removed and attached to the PCB 210. Accordingly,
the battery 215 can be easily replaced. Furthermore, the size of
the battery clip 205 and the PCB 210 can be varied according to the
diameter and thickness of any battery or type of battery--thereby
minimizing the possibility of attaching the wrong type, size or
diameter battery.
[0020] The PCB 210 and the battery clip 205 can form a discrete
component that is not manufactured as a portion of a main system
board, e.g., a motherboard. That is the PCB 210 and the battery
clip 205 can be manufactured and sold separately from any system
board. As can be appreciated, the discrete component including the
PCB 210 and the battery clip 205 can be attached to a system board
at any time.
[0021] Referring now to FIG. 3, there is illustrated a block
diagram of the electronics of the battery holder 200 shown in FIG.
2. The battery monitoring IC 225, as shown in FIG. 3, is connected
to five lines: a supply voltage line 235, a serial data line 240, a
serial clock line 245, a battery output line 250, and a ground 255.
These lines are generally connected to separate ones of pins 230
(shown in FIG. 2). The serial data line 240 and the serial clock
line 245 form a 2-wire interface used to communicate with the
battery monitoring IC 225. Furthermore, for control purposes, both
the serial data line 240 and the serial clock line 245 are
connected to the supply voltage line 235 by individual resistors
260 and 265.
[0022] In operation, the battery monitoring IC 225 operates by
comparing the existing battery's condition against known battery
characteristics. This is done while supply voltage is being applied
to the battery monitoring IC 225 and while the battery is not
loaded by the system. More particularly, the battery monitoring IC
225 performs a pair of voltage measurements on the battery output
line 250. The first measurement is a voltage measurement taken when
there is no load. The second measurement is also a voltage
measurement. However, the second measurement is taken when there is
a load. The difference between these two measurements is DELTA-V.
The measurement DELTA-V, when taken over time, can be used to gauge
the remaining useful capacity of the battery 215. Alternatively, a
single DELTA-V measurement can indicate that the battery is nearing
the end of its useful life.
[0023] FIG. 4 illustrates a typical "voltage vs. time" plot for a
no-load voltage measurement and a loaded voltage measurement.
Measurement plot 270 represents an exemplary plot of the voltage
for the no-load measurement and measurement plot 275 represents an
example of the voltage plot for the loaded measurement. The
difference between these two measurement plots at a particular time
is represented by DELTA-V 280.
[0024] As illustrated by FIG. 4, the typical battery and its
voltage output capacity continually degrade. By monitoring DELTA-V
280, a low battery can be identified before the battery is
completely drained. As can be appreciated, the voltage from the
no-load measurement 270 remains fairly constant until the battery
is virtually depleted (time t2). The voltage from the loaded
measurement 275, on the other hand, begins to fall rapidly near the
end of the battery's life (after time ti) but well before the
battery is depleted (time t2). Accordingly, DELTA-V grows
substantially near the end of the battery's life (after time t1).
The battery monitoring IC 225 can detect this growth in DELTA-V or
detect when DELTA-V exceeds a certain threshold and notify a user
that the battery 215 is nearing failure and should be replaced.
Alternatively, battery monitoring IC 225 can provide the DELTA-V
information to other circuitry that can notify the user of the
battery's condition.
[0025] FIG. 4 represents only an exemplary plot of the "load vs.
no-load" characteristics of a primary battery. Each type of
battery, e.g., CR (lithium/manganese dioxide) and BR
(lithium/carbon monofluoride), has its own characteristics that can
be programmed into the battery monitoring IC 225. Thus, the battery
monitoring IC 225 can be adapted to detect a low battery condition
for any battery chemistry. Furthermore, the battery monitoring IC
225 can be programmed to detect a low battery condition for any
particular battery capacity or other battery characteristic.
[0026] Referring now to FIG. 5, there is illustrated a more
detailed block diagram of the battery monitoring IC 225 shown in
FIGS. 2 and 3. In this embodiment, the battery monitoring IC 225
includes a logic element 285 connected to both a serial interface
290 and a register bank 295, which includes a battery low output
315. The battery monitoring IC 225 also includes a battery removal
detector 300 and a measure control logic 305, both of which are
connected to the register bank 295. Furthermore, the measure
control logic 305, which provides various logical capabilities, is
connected to an analog-to-digital (A/D) converter 310.
[0027] Continuing to refer to FIG. 5, a DELTA-V measurement cycle
is initiated whenever the supply voltage 235 is cycled or upon
command from the host system (not shown) through the use of the
register bank 295. As can be appreciated, for systems that are
rarely powered down, the host system has the primary responsibility
for initiating the DELTA-V measurement.
[0028] When a DELTA-V measurement cycle is initiated, the battery
monitoring IC 225 measures the no-load battery voltage. Next, the
battery monitoring IC 225 attaches a load to the battery for a
select amount of time and takes a voltage measurement during that
time. Although the size of the load and the length of time that the
load is attached to the battery can vary, particularly good results
have been obtained by attaching a 1.2 M.OMEGA. load for one second.
Because voltage measurements are generally analog, both
measurements are converted to a digital format using the A/D
converter 310. In one embodiment, the voltage measurement is an
8-bit successive approximation of the analog voltage measurement.
One skilled in the art, however, can understand that other voltage
measurement and/or data conversion schemes can be used to achieve
similar results.
[0029] After both measurements have been taken and converted, the
DELTA-V value is determined and stored in the register bank 295.
This DELTA-V value is available over the 2-wire bus (lines 240 and
245 connected to the serial interface 290) to a host system (not
shown) for particular battery monitoring options. Although
particularly good results have been obtained by using the 2-wire
bus, it is contemplated that other interfaces can be used instead
of the 2-wire bus.
[0030] Next, when the DELTA-V sensing circuit 285 senses that the
battery 215 is low, i.e., below a certain threshold, a battery
status bit (not shown) in the register bank 295 is set to logic 0
and the battery low output 315 is driven to active low. Once set,
the battery status bit remains logic 0 and the battery low output
315 remains asserted until the battery 215 is physically
replaced.
[0031] The logic element also controls two additional bits in the
register bank 295: a measurement status bit and a new measurement
bit (neither of which are illustrated). The measurement status bit
is set when a DELTA-V measurement cycle is in progress. The new
measurement bit is set when a DELTA-V measurement cycle
completes.
[0032] Continuing to refer to FIG. 5, the battery removal detector
300 can detect when the battery 215 (shown in FIGS. 2 and 3) is
removed from or inserted into the battery holder 200 (also shown in
FIGS. 2 and 3) and, responsive to detection of a battery 215
removal/insertion, set a no-battery bit in register bank 295. When
the battery is replaced, the no-battery bit is flipped.
Furthermore, when the battery is replaced, the new battery bit is
set to logic 1. One advantage of the battery removal detector 300
is that it enables the battery 215 to be replaced while the system
is "hot" or powered up.
[0033] Although the register bank 295 can be arranged in a variety
of ways, particularly good results have been obtained when the
register bank 295 includes a status register, a control register
and a DELTA-V register (none of which are illustrated). The status
register included in the register bank 295 provides information
regarding the DELTA-V measurement process, the battery capacity
state and battery replacement detection. Furthermore, the bits in
the status register fall into two additional categories: those that
are cleared after they are read and those are not affected by being
read. For example, the new measurement bit and the new battery bit
are cleared after they are read. The measurement status bit, the
battery status bit and the no battery bit, on the other hand, are
not affected by being read.
[0034] In an exemplary embodiment, the control register (not shown)
included in the register bank 295 can be a write only register that
is used to initiate a DELTA-V measurement cycle. In operation, a
host system can write a logic 1 to this register and cause the
logic element 285 to perform a DELTA-V measurement. The control
register is particularly important for systems that are rarely
powered down because the system can initiate a DELTA-V measurement
cycle instead of waiting for the system to be powered down and back
up.
[0035] The DELTA-V measurement register (not shown) included in the
register bank 295 stores the results of the most recent DELTA-V
measurement cycles. In one embodiment, the DELTA-V measurement
register is a read only register that stores the last eight DELTA-V
measurements. These stored DELTA-V measurements are accessible to
the host system through the 2-wire bus (serial data line 240,
serial clock line 245 and serial interface 290).
[0036] In conclusion, one skilled in the art can appreciate that
the present invention provides an apparatus for monitoring the
condition of a battery. In the exemplary embodiment, a battery clip
is used to secure a battery to a battery connection and a battery
monitoring IC. The battery monitoring IC takes a "load vs. no-load
measurement" while Vcc is applied, and the results are recorded in
a register. When the battery reaches a certain low voltage state,
register bits are set and an output is generated. Furthermore, the
exemplary embodiment includes a removal detection circuit for
detecting removal and replacement of the battery and for preventing
voltage float on the battery output line.
[0037] Those skilled in the art will readily recognize that
numerous variations and substitutions may be made in the invention,
its use and its configuration to achieve substantially the same
results as achieved by the embodiments described herein. For
example, bit configurations, logic values and component groupings
can be easily altered. Accordingly, there is no intention to limit
the invention to the disclosed exemplary forms. Many variations,
modifications and alternative constructions will fall within the
scope and spirit of the disclosed invention as expressed in the
claims.
* * * * *