U.S. patent application number 12/659392 was filed with the patent office on 2010-07-01 for power source switching apparatus and method thereof.
Invention is credited to Jong-Sang Choi.
Application Number | 20100164294 12/659392 |
Document ID | / |
Family ID | 37803191 |
Filed Date | 2010-07-01 |
United States Patent
Application |
20100164294 |
Kind Code |
A1 |
Choi; Jong-Sang |
July 1, 2010 |
Power source switching apparatus and method thereof
Abstract
A power source switching apparatus and method thereof are
provided. The example power source switching apparatus may include
a battery storing charges received from an external power source
and outputting a voltage corresponding to the stored charges, a
voltage adjuster outputting a first power source voltage having a
voltage level, corresponding to the output voltage of the battery,
during an external power source mode where the battery is being
charged, the first power source voltage based at least in part on
the external power source and the output voltage of the battery, a
controller outputting a first control signal and a second control
signal, the first control signal enabled if the battery is
operating in the external power source mode and the second control
signal is enabled if the battery is not operating in the external
power source mode, a first switch outputting the first power source
voltage if the first control signal is enabled and a second switch
outputting the output voltage of the battery if the second control
signal is enabled. In an example method, a first power source
voltage may be provided if a battery is not being charged by an
external power source voltage, the first power source voltage
output by the battery. A second power source voltage may be
provided if the battery is being charged by the external power
source voltage, the second power source voltage corresponding to a
voltage level of the first power source voltage and not provided
from the battery.
Inventors: |
Choi; Jong-Sang; (Seoul,
KR) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 8910
RESTON
VA
20195
US
|
Family ID: |
37803191 |
Appl. No.: |
12/659392 |
Filed: |
March 8, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11508920 |
Aug 24, 2006 |
7683584 |
|
|
12659392 |
|
|
|
|
Current U.S.
Class: |
307/80 |
Current CPC
Class: |
H02J 7/0068
20130101 |
Class at
Publication: |
307/80 |
International
Class: |
H02J 1/00 20060101
H02J001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 24, 2005 |
KR |
10-2005-0078047 |
Claims
1. A power source switching apparatus, comprising: a first power
source unit supplying a first voltage which is applied to a system
load during a first power source mode; a second power source unit
supplying a second voltage which is applied to a system load during
a second power source mode and charged by the first voltage; and a
voltage adjuster controlling that the first voltage has the same
voltage level of the second voltage while the second voltage is
being charged so as to maintain a level of voltage applied to the
system load during a transition between the first power source mode
and the second power source mode.
2. The power source switching apparatus of claim 1, wherein the
first voltage is an external power source voltage.
3. The power source switching apparatus of claim 1, wherein the
second voltage is an output voltage of a battery.
4. The power source switching apparatus of claim 1, further
comprising: a battery charger supplying charges from the first
power source unit to the second power source unit.
5. The power source switching apparatus of claim 1, further
comprising: a first switch applying the first voltage to the system
load in responding to a first control signal; and a second switch
applying the second voltage to the system load in responding to a
second control signal.
6. The power source switching apparatus of claim 1, further
comprising: a controller outputting a first control signal enabled
during the first power source mode and a second control signal
enabled during the second power source mode.
7. The power source switching apparatus of claim 1, wherein the
voltage adjuster comprises: an operational amplifier including a
first input terminal receiving the first voltage and a second input
terminal connected to the system load; and a MOS transistor
including a first terminal applied the first voltage, a second
terminal connected to the system load.
8. The power source switching apparatus of claim 7, wherein the
voltage adjuster further includes: a load including a first
terminal connected to the second input terminal of the operational
amplifier and the second input terminal of the MOS transistor.
Description
PRIORITY STATEMENT
[0001] This application is a Continuation of U.S. application Ser.
No. 11/508,920 filed Aug. 24, 2006, which claims priority from
Korean Patent Application No. 10-2005-0078047, filed on Aug. 24,
2005, in the Korean Intellectual Property Office, the disclosure of
which is incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Example embodiments of the present invention are directed
generally to a power source switching apparatus and method thereof,
and more particularly to a power source switching apparatus and
method of providing power.
[0004] 2. Description of the Related Art
[0005] A portable mobile device may be used in places where an
external power source voltage may not be available because the
portable mobile device may be configured to operate with an
internal power source voltage applied by a battery. Portable mobile
devices may be configured to use rechargeable batteries and/or
disposable batteries. Rechargeable batteries may typically be
charged by external power source voltages. A charge capacity of
rechargeable batteries may typically be relatively limited, and
therefore rechargeable batteries may need to be recharged from time
to time as charges stored therein are exhausted.
[0006] For example, a user may charge a rechargeable battery during
a period where the portable mobile device may be powered by an
external power source voltage. In other words, the portable mobile
device may draw power from the external power source to both power
the portable mobile device as well as charge the rechargeable
battery.
[0007] FIG. 1 is a block diagram illustrating a conventional
portable mobile device. Referring to FIG. 1, the portable mobile
device may include a voltage drop diode 120, a controller 130, a
battery charger 140, a battery 150, a direct current (DC)-DC
converter 160, a system load 170, and a switch SW1.
[0008] Referring to FIG. 1, the voltage drop diode 120 may be used
if charges are supplied to the battery 150 via the battery charger
140 while the portable mobile device is powered by an external
power source 110. An operating voltage of the system load 170 may
be lower than a voltage of the external power source 110 in order
to reduce power consumption of the system load 170. Accordingly,
the voltage of the external power source 110 may be reduced or
dropped using at least one voltage drop diode 120 connected in
series, and the reduced voltage may then be supplied to the system
load 170. The controller 130 may generate a control signal CON for
selecting one of the voltage of the external power source 110
(e.g., applied through the voltage drop diode 120) and the voltage
of the battery 150.
[0009] Referring to FIG. 1, the battery charger 140 may charge the
battery 150 using the external power source 110. During charging,
the battery 150 may receive charges from the battery charger 140.
The battery 150 may output a voltage corresponding to a voltage
level at which the battery 150 is charged. The switch SW1 may
supply one of the output voltage of the battery 150 and the output
voltage of the voltage drop diode 120 to the DC-DC converter 160,
in response to the control signal CON output from the controller
130. The DC-DC converter 160 may convert the voltage supplied
through the switch SW1 into a voltage having a level which may be
sufficient to power the system load 170. The system load 170 may
indicate a functional block which may perform a specific function
using the voltage supplied from the DC-DC converter 160.
[0010] FIG. 2 is a block diagram illustrating another conventional
portable mobile device. Referring to FIG. 2, the output voltage of
a voltage drop diode 220 may be directly supplied to a system load
270 through a switch SW2, and the output voltage of a battery 250
may be supplied to a DC-DC converter 260 through a second switch
SW3. The two switches SW2 and SW3 may be controlled by a control
signal CON output from a controller 230 and a signal which may be
obtained by inverting a phase of the control signal CON through an
inverter 280, respectively. Accordingly, the first switch SW2 and
the second switch SW3 may be turned on and off, respectively, or
vice versa.
[0011] The conventional portable mobile devices illustrated in
FIGS. 1 and 2 may each have (i) a battery mode in which the
portable mobile device may be powered by a battery and (ii) an
external power source mode in which the battery may be charged via
the external power source while the portable mobile device is
either operating via the external power source or not operating.
During a transition between the battery mode and the external power
source mode (e.g., in response to plugging in or unplugging the
portable mobile device), a voltage supplied to the DC-DC converter
160 or the system load 270 may change at a relatively high
rate.
[0012] FIGS. 3A, 3B and 3C illustrate a supplied voltage during a
first transition from a battery mode to an external power source
mode and a second transition from the external power source mode
back to the battery mode. In an example, the supplied voltage
illustrated in FIG. 3 may represent a voltage applied to the DC-DC
converter 160 and/or the system load 270.
[0013] FIG. 3A illustrates a theoretical voltage level fluctuation
of the power source voltage applied during a transition between the
battery mode and the external power source mode. The theoretical
voltage level of FIG. 3A is not intended to represent a capability
of the conventional art, but is rather intended to illustrate a
conceptual "ideal" voltage transition having a linear or "smooth"
voltage change during a power source transition.
[0014] Referring to FIG. 3A, in a battery mode Bat_mode, a level of
the power source voltage applied to the system may gradually be
reduced over time. The external power source mode Recharge_mode for
charging may be initiated before the voltage reaches a lower
threshold voltage V.sub.RL. In the external power source mode
Recharge_mode, the voltage of the battery may increase, and the
external power source mode Recharge_mode may be switched to the
battery mode Bat_mode before the voltage reaches a higher threshold
voltage V.sub.RH. In an example, the lower threshold voltage
V.sub.RL may represent a minimum voltage level required to power
the portable mobile device and the higher threshold V.sub.RH may
represent a voltage level above which the portable mobile device
may not be capable of safe operation.
[0015] However, in a real-world environment, the external power
source may have a voltage level at least equal to the lower voltage
V.sub.RH because, typically, a voltage used to charge a battery may
be set to a voltage level higher than a voltage level to which the
battery is configured to be charged. Hereinafter, it may be that
the external power source voltage may be set to Vpp.
[0016] FIG. 3B illustrates a conventional voltage level fluctuation
of the power source voltage applied during a transition between the
battery mode and the external power source mode.
[0017] Referring to FIG. 3B, in the instant when the battery mode
is switched to the external power source mode or the instant when
the external power source mode is switched to the battery mode, a
voltage level of the external power source voltage may spike (e.g.,
rapidly change). Furthermore, because the power source voltage may
be set to Vpp, which may be higher than the lower voltage V.sub.RH,
in the external power source mode Recharge_mode, the battery may be
charged by the power source voltage Vpp but the power source
voltage Vpp may be too high to safely supply power to the portable
mobile device. Accordingly, the portable mobile device may be
inoperable during battery charging because the voltage used to
charge the battery may be unsuitable to power the portable mobile
device.
[0018] FIG. 3C illustrates another conventional voltage level
fluctuation of the power source voltage applied during a transition
between the battery mode and the external power source mode.
[0019] Referring to FIG. 3C, if the external power source voltage
is reduced to the same voltage as the lower voltage V.sub.RH using
a plurality of voltage drop diodes which are connected to each
other in series, the power source voltage (e.g., set to V.sub.RH)
may be supplied to a system load of the portable mobile device.
Accordingly, because the external power source voltage may be
maintained at the lower voltage V.sub.RH, the external power source
voltage may be applied to the system while the battery is charged
(e.g., although the charging of the battery may take a longer
period of time due to the lower charging voltage). However, in FIG.
3C, similar to FIG. 3B, in the instant of switching the battery
mode to the external power source mode or switching the external
power source mode to the battery mode, the power source voltage may
spike or change rapidly, thereby degrading a performance of the
portable mobile device.
SUMMARY OF THE INVENTION
[0020] An example embodiment of the present invention is directed
to a power source switching apparatus, including a battery storing
charges received from an external power source and outputting a
voltage corresponding to the stored charges, a voltage adjuster
outputting a first power source voltage having a voltage level,
corresponding to the output voltage of the battery, during an
external power source mode where the battery is being charged, the
first power source voltage based at least in part on the external
power source and the output voltage of the battery, a controller
outputting a first control signal and a second control signal, the
first control signal enabled if the battery is operating in the
external power source mode and the second control signal is enabled
if the battery is not operating in the external power source mode,
a first switch outputting the first power source voltage if the
first control signal is enabled and a second switch outputting the
output voltage of the battery if the second control signal is
enabled.
[0021] Another example embodiment of the present invention is
directed to a method of providing power, including providing a
first power source voltage if a battery is not being charged by an
external power source voltage, the first internal power source
voltage output by the battery and providing a second power source
voltage if the battery is being charged by the external power
source voltage, the second power source voltage corresponding to a
voltage level of the first power source voltage and not provided
from the battery.
[0022] Another example embodiment of the present invention is
directed to a power source switching apparatus in which a power
source voltage may not be rapidly changed when a battery mode and
an external power source mode are mutually switched.
[0023] Another example embodiment of the present invention is
directed to a power source switching method in which a power source
voltage may not be rapidly changed when a battery mode and an
external power source mode are mutually switched.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
example embodiments of the present invention and, together with the
description, serve to explain principles of the present
invention.
[0025] FIG. 1 is a block diagram illustrating a conventional
portable mobile device;
[0026] FIG. 2 is a block diagram illustrating another conventional
portable mobile device;
[0027] FIG. 3A illustrates a theoretical voltage level fluctuation
of the power source voltage applied during a transition between the
battery mode and the external power source mode;
[0028] FIG. 3B illustrates a conventional voltage level fluctuation
of the power source voltage applied during a transition between the
battery mode and the external power source mode;
[0029] FIG. 3C illustrates another conventional voltage level
fluctuation of the power source voltage applied during a transition
between the battery mode and the external power source mode;
[0030] FIG. 4 illustrates a power source switching apparatus
according to an example embodiment of the present invention;
[0031] FIG. 5 illustrates a power source switching apparatus
according to another example embodiment of the present
invention;
[0032] FIG. 6 illustrates a power source switching apparatus
according to another example embodiment of the present
invention;
[0033] FIG. 7 illustrates a power source switching apparatus
according to another example embodiment of the present invention;
and
[0034] FIG. 8 illustrates a voltage level fluctuation of the power
source voltage applied during a transition between the battery mode
and the external power source mode according to an example
embodiment of the present invention.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE PRESENT
INVENTION
[0035] Example embodiments of the present invention are described
more fully hereinafter with reference to the accompanying drawings,
in which example embodiments of the present invention are shown.
Example embodiments of the present invention may, however, be
embodied in many different forms and should not be construed as
limited to the example embodiments set forth herein. Rather, these
example embodiments are provided so that this disclosure will be
thorough and complete, and will fully convey the scope of the
invention to those skilled in the art. Like numbers refer to like
elements throughout.
[0036] It will be understood that although the terms first and
second are used herein to describe elements and should not be
limited by these terms. These terms are used to distinguish one
element from another. Thus, a first element discussed below could
be termed a second region, layer or section, and similarly, a
second element may be termed a first element without departing from
the teachings of the present invention.
[0037] The terminology used herein is for the purpose of describing
particular embodiments and is not intended to be limiting of the
invention. As used herein, the singular forms "a," "an" and "the"
are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It will be further understood
that the terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof.
[0038] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and will not be
interpreted in an idealized or overly formal sense unless expressly
so defined herein.
[0039] FIG. 4 illustrates a power source switching apparatus 400
according to an example embodiment of the present invention.
[0040] In the example embodiment of FIG. 4, the power source
switching apparatus 400 may include an external power source 410, a
voltage adjuster 420, a battery charger 430, a controller 440, a
battery 450, a DC-DC converter 460, a system load 470, a first
switch SW1 and a second switch SW2.
[0041] In the example embodiment of FIG. 4, the external power
source 410 may supply a power source voltage to the power source
switching apparatus 400. In an example, a voltage Vpp of the
external power source 410 may be at least equal to a lower voltage
V.sub.RH output from the battery 450 (e.g., wherein the lower
voltage V.sub.RH may represent a minimum voltage capable of being
output from the battery 450).
[0042] In the example embodiment of FIG. 4, the voltage adjuster
420 may output a first power source voltage Vc having the same
voltage level as that of the output voltage of the battery 450
during a charging of the battery 450, based on output voltages of
the external power source 410 and the battery charger 430. The
voltage adjuster 420 may include an operational amplifier OP, a
P-type MOS transistor MP, and a load 421. A first input terminal
(-) of the operational amplifier OP may receive the output voltage
Vb of the battery 450. The source terminal of the P-type MOS
transistor MP may be connected to the external power supply 410,
and the drain terminal thereof may be connected to a second input
terminal (+) of the operational amplifier OP, thereby outputting
the first power source voltage Vc. The output voltage of the
operational amplifier OP may be applied to the gate terminal of the
P-type MOS transistor MP. A first terminal of the load 421 may be
connected to a node for connecting the second input terminal (+) of
the operational amplifier OP with the drain terminal of the P-type
MOS transistor MP, and a second terminal of the load 421 may be
connected to a ground voltage GND. Although not illustrated, the
load 421 may be alternatively embodied as a capacitor with a first
terminal connected to a node for connecting the second input
terminal of the operational amplifier OP with the drain terminal of
the P-type MOS transistor MP and a second terminal connected to the
ground voltage GND and/or a resistor connected to the capacitor in
parallel.
[0043] In the example embodiment of FIG. 4, the battery charger 430
may supply charges received from the external power source 410 to
the battery 450. The controller 440 may output a first control
signal CON1. In an example, the first control signal CON1 may be
enabled (e.g., set to a first logic level, such as a higher logic
level or logic "1") in the external power source mode and a second
control signal CON2 may be enabled (e.g., set to the first logic
level) in the battery mode. The battery 450 may store the charges
received from the external power source 410 and/or the charges
received from the battery charger 430, and may output the voltage
Vb corresponding to the stored charges.
[0044] In the example embodiment of FIG. 4, the first switch SW1
may switch the first power source voltage Vc (e.g., received at a
first end thereof) and may transfer the first power source voltage
Vc to the DC-DC converter 460 (e.g., connected to a second end
thereof), in response to the first control signal CON1. The second
switch SW2 may switch the output voltage Vb of the battery 450
(e.g., connected to a first end thereof) and may transfer the
output voltage Vb to the DC-DC converter 460 (e.g., connected to a
second end thereof), in response to the second control signal CON2.
A voltage selected by the first switch SW1 and the second switch
SW2 may be referred to as a switching voltage. Because the first
switch SW1 and the second switch SW2 may configured such that only
one of the first and second switches SW1 and SW2 may be turned on
or enabled at any given time, only one switched or transferred
voltage may be applied to the DC-DC converter 460.
[0045] In the example embodiment of FIG. 4, the DC-DC converter 460
may generate a conversion voltage having a voltage level different
from that of the received switching voltage. In an example, the
level of the switching voltage may be higher than that of the
conversion voltage. In a further example, the system load 470 may
perform an operation based on the conversion voltage output by the
DC-DC converter 460.
[0046] FIG. 5 illustrates a power source switching apparatus 500
according to another example embodiment of the present
invention.
[0047] In the example embodiment of FIG. 5, the power source
switching apparatus 500 may include an external power source 510, a
voltage adjuster 520, a battery charger 530, a controller 540, a
battery 550, a DC-DC converter 560, a system load 570, a first
switch SW1, and a second switch SW2.
[0048] The example embodiment illustrated in FIG. 5 may differ from
the example embodiment illustrated in FIG. 4 in that the first
switch SW1 may deliver the first voltage Vc to the system load 570
directly (e.g., bypassing the DC-DC converter 560) and the second
switch SW2 may deliver the output voltage Vb of the battery 550 to
the DC-DC converter 560. In contrast, each of the first and second
switches SW1 and SW2 may output respective switching voltages to
the DC-DC converter 460 in the example embodiment of FIG. 4. Other
elements present in FIG. 5 corresponding to elements in FIG. 4 may
be considered to be identical for the purposes of explanation.
Accordingly, the external power source 510, the voltage adjuster
520, the battery charger 530, the controller 540, the battery 550,
a the system load 570, and the second switch SW2 in the example
embodiment of FIG. 5 may be configured in a manner identical to
that of the external power source 410, the voltage adjuster 420,
the battery charger 430, the controller 440, the battery 450, a the
system load 470, and the second switch SW2 in the example
embodiment of FIG. 4.
[0049] In example operation of the power source switching apparatus
400 illustrated in FIG. 4, in the battery mode, the voltage Vb
output from the battery 450 may be delivered to the DC-DC converter
460 via the second switch SW2, which may operate in response to the
second control signal CON2. In the external power source mode, the
first power source voltage Vc output from the voltage adjuster 420
may be delivered to the DC-DC converter 460 via the first switch
SW1, which may operate in response to the first control signal
CON1.
[0050] In example operation of the power source switching apparatus
500 illustrated in FIG. 5, in the battery mode, the voltage Vb
output from the battery 550 may be delivered to the DC-DC converter
560 via the second switch SW2, which may operate in response to the
second control signal CON2. In the external power source mode, the
first power source voltage Vc output from the voltage adjuster 520
may be delivered to the system load 570 via the first switch SW1,
which may operate in response to the first control signal CON1.
[0051] Because the voltage levels of the first power source
voltages Vc output from the voltage adjusters 420 and 520 may be
substantially the same as the voltages Vb output from the charging
batteries 450 and 550, a voltage fluctuation during a transition
between battery mode and external power source mode within the
power source switching apparatuses 400 and 500 may not experience a
rapid voltage change or spike.
[0052] In the example embodiments of FIGS. 4 and 5, the output
voltages Vb of the charging batteries 450 and 550 may be applied to
the input terminals (-) of the respective operational amplifiers
OP. Because the operational amplifiers OP may feedback via the
P-type MOS transistor MP, the output voltages of the operational
amplifiers OP may have substantially the same levels as those of
the output voltages Vb of the charging batteries 450 and 550.
[0053] FIG. 6 illustrates a power source switching apparatus 600
according to another example embodiment of the present
invention.
[0054] In the example embodiment of FIG. 6, the power source
switching apparatus 600 may include an external power source 610, a
voltage adjuster 620, a battery charger 630, a controller 640, a
battery 650, a DC-DC converter 660, a system load 670, a first
switch SW1, and a second switch SW2.
[0055] In the example embodiment of FIG. 6, the external power
source 610 may supply a power source voltage to the power source
switching apparatus 600. In an example, the voltage Vpp of the
external power source 610 may be at least equal to a lower voltage
V.sub.RH output from the battery 650 (e.g., wherein the lower
voltage V.sub.RH may represent a minimum voltage capable of being
output from the battery 650).
[0056] In the example embodiment of FIG. 6, the voltage adjuster
620 may output a first power source voltage Vc having substantially
the same level as that of the output voltage Vb of the battery 650
during a charging of the battery 650. The first power source
voltage Vc may be based on a third control signal CON3 and the
output voltages of the external power source 610 and the battery
650. The voltage adjuster 620 may include an operational amplifier
OP, a P-type MOS transistor MP, a third switch SW3, and a load 621.
A first input terminal (-) of the operational amplifier OP may
receive the output voltage Vb of the battery 650. The source
terminal of the P-type MOS transistor MP may be connected to the
external power supply 610, the drain terminal thereof may be
connected to the second input terminal (+) of the operational
amplifier OP. The third switch SW3 may switch one of the output
voltages of the external power source 610 and the operational
amplifier OP and may deliver the output voltage Vc to the gate
terminal of the P-type MOS transistor MP. The source terminal of
the P-type MOS transistor MP may be connected to the external power
supply 610, and the drain terminal thereof may be connected to the
second input terminal (+) of the operational amplifier OP, thereby
outputting the first power source voltage Vc.
[0057] In the example embodiment of FIG. 6, a first terminal of the
load 621 may be connected to a node for connecting the second input
terminal (+) of the operational amplifier OP with the drain
terminal of the P-type MOS transistor MP, and a second terminal of
the load 621 may be connected to a power source terminal GND. In an
example, the load 621 may be embodied as a capacitor (not
illustrated) with a first terminal connected to a node for
connecting the second input terminal (+) of the operational
amplifier OP with the drain terminal of the P-type MOS transistor
MP and with a second terminal connected to the power source
terminal GND and/or a resistor connected to the capacitor in
parallel.
[0058] While the example embodiment of FIG. 6 illustrates the
output terminal of the operational amplifier OP connected with the
P-type MOS transistor MP, it is understood that another example
embodiment of the present invention may include an N-type MOS
transistor in place of the P-type MOS transistor MP (e.g., wherein
the signals applied to the two input terminals (+) and (-) of the
operational amplifier OP may be swapped with each other in the
N-type MOS transistor example embodiment as opposed to the P-type
MOS transistor example embodiment).
[0059] In the example embodiment of FIG. 6, the battery charger 630
may be positioned between the external power source 610 and the
battery 650. The battery charger 630 may supply charges generated
using the external power source 610 to the battery 650. The
controller 640 may output a first control signal CON1 and the third
control signal CON3, which may be enabled in the external power
source mode, and a second control signal CON2, which may be enabled
in the battery mode. In an example, only one of the first control
signal CON1 and the second control signal CON2 may be enabled at
any given time. The third control signal CON3 may be enabled at a
time period preceding an enablement of the first control signal
CON1, and the third control signal CON3 may be disabled
concurrently with a disabling of the first control signal CON1. In
an example, the time period of which the third control signal CON3
may be enabled before an enablement of the first control signal
CON1 may be a settling time until the voltage Vc output from the
voltage adjuster 620 may achieve the same voltage level as that of
the output voltage Vb of the battery 650. The battery 650 may store
the charges directly applied from the external power source 610, or
alternatively the charges applied from the battery charger 630, and
may output the voltage Vb corresponding to the stored charges.
[0060] In the example embodiment of FIG. 6, the first switch SW1
may switch the first power source voltage Vc supplied to a first
end thereof in response to the first control signal CON1. The
second switch SW2 may switch the output voltage Vb of the battery
650 connected to a first end thereof in response to the second
control signal CON2. A second end of the first switch SW1 may be
connected with a second end of the second switch SW2. The voltage
output from the common node of the first switch SW1 and/or the
second switch SW2 may be referred to as a switching voltage.
[0061] In the example embodiment of FIG. 6, the DC-DC converter 660
may generate a conversion voltage having a voltage level different
from that of the switching voltage based on the switching voltage
(e.g., an offset thereof). In an example, the voltage level of the
switching voltage may be higher than that of the conversion
voltage. The system load 670 may perform a given function using the
conversion voltage output by the DC-DC converter 660.
[0062] FIG. 7 illustrates a power source switching apparatus 700
according to another example embodiment of the present
invention.
[0063] In the example embodiment of FIG. 7, the power source
switching apparatus 700 may include an external power source 710, a
voltage adjuster 720, a battery charger 730, a controller 740, a
battery 750, a DC-DC converter 760, a system load 770, a first
switch SW1, and a second switch SW2. The example embodiment
illustrated in FIG. 7 may be different from the example embodiment
illustrated in FIG. 6 in that the two switches SW1 and SW2 may be
connected to the DC-DC converter 760 and the system load 770,
respectively. Accordingly, in the example embodiment of FIG. 7, the
first switch SW1 may directly delivers the first voltage Vc to the
system load 770 and the second switch SW2 deliver the output
voltage Vb of the battery 750 to the DC-DC converter 760. The
remaining elements present in the example embodiment of FIG. 7 may
be generally identical to corresponding elements in the example
embodiment of FIG. 6, and as such a further description thereof has
been omitted for the sake of brevity.
[0064] In example operation of the power source switching apparatus
600 of FIG. 6, in the battery mode, the voltage Vb output from the
battery 650 may be delivered to the DC-DC converter 660 via the
second switch SW2, which may operate in response to the second
control signal CON2. In the external power source mode, the first
power source voltage Vc output from the voltage adjuster 620 may be
delivered to the DC-DC converter 660 via the first switch SW1,
which may operate in response to the first control signal CON1.
[0065] In example operation of the power source switching apparatus
700 of FIG. 7, in the battery mode, the voltage Vb output from the
battery 750 may be delivered to the DC-DC converter 760 via the
second switch SW2, which may operate in response to the second
control signal CON2. In the external power source mode, the first
power source voltage Vc output from the voltage adjuster 720 may be
delivered to the system load 770 via the first switch SW1, which
may operate in response to the first control signal CON1.
[0066] In each of the power source switching apparatuses 600 and
700 illustrated in the example embodiments of FIGS. 6 and 7, a
power source voltage may not change rapidly during a transition
between the battery mode and the external power source mode because
voltage levels of the first power source voltages Vc output from
the voltage adjusters 620 and 720 may be proximate (e.g.,
substantially equal) to those of the voltages Vb output from the
charging batteries 650 and 750.
[0067] FIG. 8 illustrates a voltage level fluctuation of the power
source voltage applied during a transition between the battery mode
and the external power source mode according to an example
embodiment of the present invention. In the example embodiment of
FIG. 8, the power source voltage may be representative of the
voltages applied to the DC-DC converters 460, 560, 660, and/or 760
and/or the system loads 470, 570, 670, and/or 770.
[0068] In the example embodiment of FIG. 8, the power source
voltage of FIG. 8 may approximate the theoretical "ideal" voltage
illustrated in FIG. 3A. In other words, the voltage level
fluctuation illustrated in FIG. 8 may be relatively smooth in
comparison to the conventional voltage level fluctuations
illustrated in FIGS. 3B and 3C. Accordingly, referring to FIG. 8,
if the battery mode Bat_mode is switched to the external power
source mode Recharge_mode, the third control signal CON3 may be
enabled such that the output voltage of the voltage adjuster may
substantially match the output voltage of the battery before a
given time period (e.g., settling time), thereby increasing system
stability.
[0069] Example embodiments of the present invention being thus
described, it will be obvious that the same may be varied in many
ways. For example, while above-described example embodiments of the
present invention are directed to maintaining a relatively stable
voltage during a transition between battery powered operation and
external power source powered operation, it will be readily
apparent that other example embodiments of the present invention
may deploy the above-described teachings to any scenario wherein a
rapid voltage change is expected and/or increased voltage stability
is desired.
[0070] Such variations are not to be regarded as a departure from
the spirit and scope of example embodiments of the present
invention, and all such modifications as would be obvious to one
skilled in the art are intended to be included within the scope of
the following claims.
* * * * *