(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2008/0272741 A1
`Kanamori
`(43) Pub. Date:
`Nov. 6, 2008
`
`US 20080272741A1
`
`(54) SYSTEMS AND METHODS FOR DETECTING
`POWER SOURCES
`(75) Inventor:
`Takashi Kanamori, San Jose, CA
`(US)
`
`Correspondence Address:
`Chad R. Walsh
`Fountainhead Law Group P.C.
`Ste. 509,900 Lafayette St.
`Santa Clara, CA 95050 (US)
`
`(73) Assignee:
`
`Summit Microelectronics, inc.,
`Sunnyvale, CA (US)
`
`(21) Appl. No.:
`
`11/973,798
`
`(22) Filed:
`
`Oct. 9, 2007
`
`Related U.S. Application Data
`(60) Provisional application No. 60/927,394, filed on May
`3, 2007.
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`HO3K 5/5
`(52) U.S. Cl. ........................................................ 320/137
`(57)
`ABSTRACT
`Embodiments of the present invention include techniques for
`detecting power Sources. In one embodiment, the present
`invention includes a method of detecting a power source
`comprising coupling a power Source to a portable electronic
`device, the power source comprising a first Supply Voltage
`and a second Supply Voltage, and at least a first data terminal
`and a second data terminal, coupling a resistor to the first data
`terminal a predetermined time period after the power source
`is coupled to the electronic device, detecting the Voltage on
`the first data terminal and second data terminal, and generat
`ing a first signal corresponding to a first power source if the
`first and second data terminals have the same Voltage after
`said predetermined time period, and generating a second sig
`nal corresponding to a second power source if the first and
`second data terminals have differential voltages after said
`predetermined time period.
`
`100
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`POWer D+
`SOUrCe D
`GND
`
`101
`
`Electronic Device
`
`System Electronics
`
`in
`
`Regulator Out
`
`103
`
`130
`
`131
`
`LGE-1013 / Page 1 of 15
`LGE v. Fundamental
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`

`

`Patent Application Publication
`
`Nov. 6, 2008 Sheet 1 of 8
`
`US 2008/0272741 A1
`
`10
`
`
`
`
`
`101
`
`Electronic Device
`
`
`
`
`
`System Electronics
`
`
`
`
`
`V+
`POWer D+
`Source D
`GND
`
`in
`
`Regulator Out
`
`103
`
`FB
`
`130
`
`131
`
`FIG. 1
`
`LGE-1013 / Page 2 of 15
`
`

`

`Patent Application Publication
`
`Nov. 6, 2008 Sheet 2 of 8
`
`US 2008/0272741 A1
`
`Full-speed or
`LOW-speed USB
`Transceiver
`
`
`
`
`
`
`
`
`15k O.5%
`
`15k.5%
`
`
`
`
`
`
`
`FIG. 2A
`
`
`
`3.0-3.6V
`
`1.5k).5%
`- Enable/Disable
`Full-speed USB
`Tranceiver
`
`Mobile Terminal
`
`FIG. 2B
`
`3.0-3.6V
`
`15k().5%
`/
`Enable? Disable
`
`Low-speed USB
`Tranceiver
`
`Mobile Terminal
`
`FIG. 2C
`
`LGE-1013 / Page 3 of 15
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`

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`Patent Application Publication
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`Nov. 6, 2008 Sheet 3 of 8
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`US 2008/0272741 A1
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`
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`LGE-1013 / Page 4 of 15
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`

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`Patent Application Publication
`
`Nov. 6, 2008 Sheet 4 of 8
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`US 2008/0272741 A1
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`
`
`
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`T-0
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`LGE-1013 / Page 5 of 15
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`

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`Patent Application Publication
`
`Nov. 6, 2008 Sheet 5 of 8
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`US 2008/0272741 A1
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`G -61-I
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`
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`Z0909
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`LGE-1013 / Page 6 of 15
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`

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`Patent Application Publication
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`Nov. 6, 2008 Sheet 6 of 8
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`US 2008/0272741 A1
`
`f) of
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`9 '61-I
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`555
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`G09
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`| 09
`
`
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`
`
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`
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`LGE-1013 / Page 7 of 15
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`Patent Application Publication
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`Nov. 6, 2008 Sheet 7 of 8
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`US 2008/0272741 A1
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`| | ||-0
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`MOI SI S
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`JOISIS88 dn ||nd
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`LGE-1013 / Page 8 of 15
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`Patent Application Publication
`
`Nov. 6, 2008 Sheet 8 of 8
`
`US 2008/0272741 A1
`
`Coupling a power source with an electronic device having a first data
`terminal and a Second data terminal
`
`
`
`Coupling a resistor to the first data terminal for a predetermined time
`period
`
`Detecting the voltage on the first data terminal and the second data
`terminal
`
`generating a first signal if the first and second data terminals have
`approximately the same voltages and a second signal if the first data
`terminal and the second data terminal have different voltages
`
`801
`
`802
`
`803
`
`804
`
`Fig. 8
`
`LGE-1013 / Page 9 of 15
`
`

`

`US 2008/0272741 A1
`
`Nov. 6, 2008
`
`SYSTEMS AND METHODS FOR DETECTING
`POWER SOURCES
`
`CROSS REFERENCE TO RELATED
`APPLICATIONS
`0001. The present application claims priority to U.S. Pro
`visional Application No. 60/927.394, titled “Systems and
`Methods for Detecting Power Sources', filed May 3, 2007.
`
`BACKGROUND
`0002 The present invention relates to providing power to
`electronic devices, and in particular, to systems and methods
`for detecting power Sources.
`0003 Electronic devices require power in the form of volt
`ages and currents to operate. Different electronic systems
`may require a wide variety of power sources with different
`Voltages and currents to operate. For example, some systems
`may operate of AC Voltages and currents and others may
`require DC voltages and currents. For AC powered systems,
`the Voltages and currents of the power source must be in some
`specified range (e.g., 11 OV AC or 220V AC). Similarly, DC
`powered systems may require that the DC voltage and DC
`currents Supplied by the power source meet certain ratings
`(e.g., 5 volts and 500 mA). However, the ratings of different
`power sources from different manufacturers may vary widely.
`Thus, it is desirable to determine the characteristics of a
`power source so that the power source may be used to provide
`power with an electronic system.
`0004 One area where power source detection is useful is
`in battery charging. Batteries have long been used as a source
`of power for mobile electronic devices. Batteries provide
`energy in the form of electric currents and Voltages that allow
`circuits to operate. However, the amount of energy stored in a
`battery is limited, and batteries lose power when the elec
`tronic devices are in use. When a battery's energy Supply
`becomes depleted, the battery's voltage will start to fall from
`its rated Voltage, and the electronic device relying on the
`battery for power will no longer operate properly. Such
`thresholds will be different for different types of electronic
`devices.
`0005. Many types of batteries are designed for a single
`use. Such batteries are discarded after the charge is depleted.
`However, some batteries are designed to be rechargeable.
`Rechargeable batteries typically require some form of battery
`charging system. Typical battery charging systems transfer
`power from a power source. Such as an AC wall plug, into the
`battery. The recharging process typically includes processing
`and conditioning Voltages and currents from the power Source
`so that the Voltages and currents Supplied to the battery meet
`the particular battery's charging specifications. For example,
`if the voltages or currents supplied to the battery from the
`power source are too large, the battery can be damaged or
`even explode. On the other hand, if the voltages or currents
`supplied to the battery from the power source are too small,
`the charging process can be very inefficient or altogether
`ineffective. Inefficient use of the battery’s charging specifi
`cation can lead to very long charging times, for example.
`Additionally, if the charging process is not carried out effi
`ciently, the battery's cell capacity (i.e., the amount of energy
`the battery can hold) may not be optimized.
`0006. Accordingly, the type of power source is an impor
`tant aspect of battery charging. One problem associated with
`charging a battery pertains to detecting the type of power
`
`Source so the system can process the Voltages and currents
`available at the power source into Voltages and currents that
`may be used to charge a battery.
`0007 Thus, there is a need for improved systems and
`methods for detecting power sources.
`
`SUMMARY
`0008 Embodiments of the present invention improve sys
`tems and methods for detecting power Sources. In one
`embodiment, the present invention includes electronic circuit
`comprising an interface controller having a power Supply
`terminal, a ground terminal, first and second data terminals,
`and an output terminal coupled to a regulator, and a detection
`circuit coupled to at least one data terminal, wherein the first
`data terminal and the second data terminal are coupled to an
`external power source and the detection circuit senses the
`Voltages on the first and second data terminals to determine
`the type of external power Source.
`0009. In one embodiment, the external power source is an
`AC adapter and wherein the first and second data terminals
`are coupled together.
`0010. In one embodiment, the first and second data termi
`nals are coupled together through a short circuit.
`0011. In one embodiment, the first and second data termi
`nals are coupled together through a resistor.
`0012. In one embodiment, interface controller receives a
`power Supply Voltage, and in accordance therewith, generates
`an enable signal, wherein the enable signal selectively
`couples a voltage to one of said first and second data termi
`nals.
`0013. In one embodiment, the interface controller outputs
`data on the output terminal to configure the regulator to
`charge a battery according to the power source type.
`0014. In one embodiment, the detection circuit comprises
`a Switch coupled to the at least one data terminal, a resistor
`coupled between the Switch and a reference Voltage, and an
`enable terminal coupled to close the switch, wherein the
`enable terminal closes the switch a predetermine time period
`after the external power source is coupled to the interface
`controller, and wherein the detector circuit configures a
`Switching regulator to charge a battery with a first current
`limit if the detector circuit senses that the first and second
`terminals are at approximately the same Voltage, and the
`detector circuit configures a Switching regulator to charge a
`battery with a second current limit if the detector circuit
`senses that the first and second terminals are at different
`Voltages.
`0015. In one embodiment, the interface controller is a
`universal serial bus controller.
`0016. In another embodiment, the present invention
`includes a method of detecting a power source comprising
`coupling a power source with an electronic device, the power
`Source comprising a first Supply Voltage terminal, a second
`Supply Voltage terminal less than the first Supply Voltage
`terminal, a first data terminal, and a second data terminal,
`coupling a resistor to the first data terminal a predetermined
`time period after the power source is coupled to the electronic
`device, detecting the Voltage on the first data terminal, and
`generating a first signal corresponding to a first power Source
`if the first and second data terminals have the same Voltage
`after said predetermined time period, and generating a second
`signal corresponding to a second power source if the first and
`second data terminals have differential voltages after said
`predetermined time period.
`
`LGE-1013 / Page 10 of 15
`
`

`

`US 2008/0272741 A1
`
`Nov. 6, 2008
`
`0017. In one embodiment, the resistor is coupled to a D+
`data terminal, and wherein electronic device comprises a full
`speed USB transceiver.
`0018. In one embodiment, the resistor is coupled to a D
`data terminal, and wherein electronic device comprises a low
`speed USB transceiver.
`0019. In one embodiment, the method further comprising
`configuring a Switching regulator to supply a first current if
`the first and second data terminals have the same Voltage after
`said predetermined time period, and configuring a Switching
`regulator to supply a second USB current if the first and
`second data terminals have differential voltages after said
`predetermined time period.
`0020. In another embodiment, the present invention
`includes a method of detecting a power source comprising
`coupling a power source with a electronic device, the power
`Source comprising a first Supply Voltage terminal, a ground
`terminal, a D+ data terminal, and a D- data terminal, detect
`ing that the power source is coupled to the electronic device,
`closing a Switch a predetermined time period after detecting
`the power source, and in accordance therewith, coupling the
`first Supply Voltage to one of said data terminals, sensing the
`Voltage on the data terminals, determining the type of the
`power source based on the sensed Voltage, and configuring a
`battery charger in the electronic device to charge the battery
`according to the type of the power Source.
`0021. In another embodiment, the configuring a battery
`charger comprises configuring a Switching regulator.
`0022. In another embodiment, the power source is an AC
`adapter having D+ and D-terminals short circuited together,
`and wherein the Voltage on the data terminals is approxi
`mately the same.
`0023. In another embodiment, the power source is a USB
`power source having a first resistor coupled between the D+
`data terminal and ground and a second resistor coupled
`between the D- data terminal and ground, and wherein the
`Voltages on the D+ data terminal and D- data terminal are
`different.
`0024. In another embodiment, the at least one data termi
`nal is the D+ terminal indicating that the electronic device
`comprises a full speed USB transceiver.
`0025. In another embodiment, the at least one data termi
`nal is the D- terminal indicating that the electronic device
`comprises a low speed USB transceiver.
`0026. The following detailed description and accompany
`ing drawings provide a better understanding of the nature and
`advantages of the present invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0027 FIG. 1 illustrates an electronic device including
`power source detection according to one embodiment of the
`present invention.
`0028 FIG. 2A-C illustrates examples of power source
`detection according to another embodiment of the present
`invention.
`0029 FIG. 3A-B illustrates an example of power source
`detection according to another embodiment of the present
`invention.
`0030 FIG. 4A-B illustrates an example of power source
`detection according to another embodiment of the present
`invention.
`0031
`FIG. 5 illustrates a battery charging system accord
`ing to one embodiment of the present invention.
`
`0032 FIG. 6 illustrates an example of power source detec
`tion according to another embodiment of the present inven
`tion.
`0033 FIGS. 7A-7B illustrates the timing diagrams for the
`circuit of FIG. 6.
`0034 FIG. 8 illustrates a method of charging a battery
`according to another embodiment of the present invention.
`
`DISCLOSURE
`0035. Described herein are techniques for battery charg
`ing systems and methods. In the following description, for
`purposes of explanation, numerous examples and specific
`details are set forth in order to provide a thorough understand
`ing of the present invention. It will be evident, however, to one
`skilled in the art that the present invention as defined by the
`claims may include some or all of the features in these
`examples alone or in combination with other features
`described below, and may further include obvious modifica
`tions and equivalents of the features and concepts described
`herein.
`0036 FIG. 1 illustrates an electronic device including a
`battery charger according to one embodiment of the present
`invention. Electronic device 101 includes system electronics
`102, a battery 150, a regulator 103 including circuitry for
`charging the battery, and a controller 130 including a power
`source detection circuit 131. System electronics may include
`microprocessors, microcontrollers, wireless electronics, net
`work electronics, or a variety of other analog or digital elec
`trical circuits that may be powered by battery 150. The elec
`tronic device may be a mobile system, portable phone (e.g., a
`cellular phone), a personal digital assistant ("PDA), a por
`table music or video player, or a variety of other mobile
`devices that may be powered by a battery. Regulator 103 may
`include an input terminal 121 coupled to a power source 110
`and an output terminal 122 coupled to a battery 150 for
`charging the battery. Regulator 103 may include a feedback
`terminal 123 for regulating Voltage or current. Example regu
`lators are linear regulators or Switching regulators, for
`example. Switching regulators may further include filters
`coupled between the regulator output and the battery, for
`example.
`0037 Embodiments of the present invention include a
`controller 130 including a power source detection circuit 131.
`In this example, power source 110 includes a power Supply
`Voltage terminal V+, which may provide Voltage and current,
`a second power Supply Voltage terminal (here, ground
`“GND), and two data terminals (“D+” and “D-”). Controller
`130 includes inputs coupled to the V+, GND, D+, and D
`terminals of the power source 110. An example controller
`may be included in electronic device 101 as a separate inte
`grated circuit, for example. As described in more detail below,
`a detection circuit 131 for detecting the power source may be
`included on the controller 130. Detection circuit may couple
`a passive network (e.g., one or more resistors) to at least one
`data terminal a predetermined time period after the power
`Source is coupled to the electronic device, and detect or sense
`the Voltages of the data terminals a predetermined time period
`after the power source is coupled to the electronic device to
`determine the type of power Source. In this example, the
`voltages would be considered an attribute of the power source
`and the type of power source would be a characteristic of the
`power source. In one embodiment, the controller 130 gener
`ates a first signal corresponding to a first power source (e.g.,
`an AC adapter) if the first and second data terminals have the
`
`LGE-1013 / Page 11 of 15
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`

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`US 2008/0272741 A1
`
`Nov. 6, 2008
`
`same Voltage after said predetermined time period, and the
`controller 130 generates a second signal corresponding to a
`second power source (e.g., a USB port power source host or
`hub) if the first and second data terminals have differential
`Voltages after said predetermined time period
`0038. For example, a Universal Serial Bus (“USB) is an
`example of a DC power Source that may be used to charge a
`battery. USB typically includes a power supply voltage, V+,
`which may be coupled to electronic device 101, for example.
`The voltage and current from the USB power source may be
`coupled through regulator 103 to power the system electron
`ics 102, or charge the battery 150, or both. However, different
`power sources, such as USB, may have different power rat
`ings. For example, Some USB power sources are designed to
`provide 5 volts and a maximum of 500 mA. Other USB power
`sources are designed to provide 5 volts and a maximum of 100
`MA. More generally, a power source capable of plugging into
`a wall power Supply may transform the AC Voltage and cur
`rent into DC voltage and current and provide a variety of
`different DC voltages and currents that may be used to power
`device 101 or charge battery 150. One example unit is a AC to
`DC converter that receives AC voltages and currents and
`outputs a USB Voltage, such as 5 volts, and a certain maxi
`mum current. The maximum current may be an attribute of
`the power source in this example. One particular problem
`with these power sources is that the current available may be
`different depending on the manufacturer, and if regulator 103
`draws more current than the power Source can Supply, then the
`Voltage of the power source will start to drop (i.e., the power
`Source will collapse). For example, wall adapters providing a
`USB compatible output may provide 300 mA, while other
`USB compatible wall adapters may provide 1500 mA or
`more. It is to be understood that the AD to DC power source
`could be a USB compatible or another AC to DC power
`source. Embodiments of the present invention may be used to
`detect whether a power source is an AC power source or a DC
`power source, for example. In this example, the characteristic
`AC or “DC corresponds to the type of power conversion
`employed by the power source.
`0039. In some embodiments, some power sources and
`interfaces for mobile terminal equipment may benefit from
`detecting a power source by reading the impedance between
`D+ and D-. In some power sources, D+ and D- may be
`shorted inside the power source, and the shorted node may be
`floating. This means that D+ and D- are shorted together or
`coupled together through a small impedance (e.g., Suffi
`ciently smaller than 1.5 kohm or 1.5 kohm).
`0040. In USB systems, D+ and D-are the signal lines used
`to implement the USB protocol. D+ and D-form a differen
`tial pair. D+ and D-lines carry binary data from an upstream
`port (e.g., a USB host or hub port) to downstream devices, or
`from downstream devices to the upstream port. If D+ and D
`is a differential pair, the Voltage level on one is typically
`greater than the other. An exception to this may be particular
`states that occur outside a predetermined time interval after
`the power source is coupled to the electronic device. For
`example, in a USB system, the Voltages on D+ and D- are
`different except in an SEO state, an SE1 state, or when a
`downstream device is not connected. The SEO is a state where
`both D+ and D- are low, and frequently asserted to signal an
`end of packet, and to signal a reset. Accordingly, SEO State
`does not occur near the time a USB power source is connected
`to the electronic device. The SE1 is a state where both D+ and
`D- are high. SE1 is not an intended state in USB.
`
`0041. The expected difference between the voltages on D+
`and D- may be used to detect the power source. In the USB
`example, 15kS25% resistors connected to ground are typi
`cally used to terminate both D+ and D-lines at host or hub
`ports. This is illustrated in FIG. 2A. At the mobile device
`terminals, a 1.5kS2+5% resistor connected to a voltage source
`between 3.0V and 3.6V may be used to pull up either D+ or
`D- as illustrated in FIGS. 2B and 2C. A pull up resistor
`coupled to the D+ line may be used to indicate a full speed
`USB controller device, and a pull up resistor coupled to the
`D-line may be used to indicate a low speed USB device, for
`example. This pull up resistor may reside inside the USB
`controller, and may be connected or disconnected by a Switch
`activated by a specific enable signal in the controller, for
`example.
`0042 FIGS. 3A-B illustrate an example technique to
`detect the upstream power source. If the upstream port is an
`AC charger power source (e.g., an AC adapter with a DC
`output), D+ and D- may be shorted together, and the shorted
`node may be floating as in FIG.3A. The mobile terminal may
`assert a specific enabling signal for the 1.5kS2+5% pull up
`resistor inside the device. For example, a controller may
`assert a signal to couple the pull up resistor to the D+ or D
`terminal after the power source is coupled to the device. If the
`power source has D+ and D-shorted together and floating,
`D+ and D- will go high when the pull up resistor is enabled a
`time period after the power source is coupled to the electronic
`device. FIG. 3B illustrates the voltages on the D+, D- and
`enable lines. At time 301 the mobile device (e.g., a mobile
`telecommunications terminal Such as a cellphone) is coupled
`to the power source. For example, a cable may be plugged into
`the power source on one side and mobile device on the other.
`After a time period, which may be predetermined according
`to an internal clock, circuit delays, or other detector settings,
`the enable signal may couple the pull up resistor to the D+ or
`D- lines. The pull up resistor will cause both D+ and D
`terminals to increase in Voltage. Since D+ and D- are shorted,
`it does not matter if the 1.5kS2+5% is located on D+ side or on
`D-side. Both D+ and D- will get pulled up simultaneously.
`0043 Alternatively, the upstream port may not be a power
`source with D+ and D– are shorted. If the connector for the
`upstream port is a USB connector, the upstream port is most
`likely to be a PC USB port. A PC USB port operates under
`USB protocol specified by Universal Serial Bus Specification
`Revision 2.0. Accordingly, the 15k2+5% pull down resistors
`are required on D+ and D- at the upstream port as in FIG. 4A.
`Upon connection of the cable, the mobile device asserts a
`specific enabling signal for the 1.5kS2+5% pull up resistor.
`This may be implemented in the USB controller (sometimes
`referred to as the USB PHY), for example. The 1.5kS2+5%
`pull up resistor is a much stronger pull up than 15kS2+5% pull
`down resistor. Accordingly, with a USB port power source,
`only one of the two signal lines, D+or D will be pulled up
`high, while the other is pulled down by the 15kS2+5% pull
`down resistor. Hence, only D+ should be pulled high for full
`speed device, and only D-should be pulled up high for low
`speed device. The dashed line in FIG. 4A between D+ and D
`illustrates that the pull up resistor may be coupled to either the
`D+ or D-line. The dashed line is the case where the pull up
`resistor is coupled to D- and not D+. This non-correspon
`dence between the first voltage, on the first data terminal, D+,
`and the second Voltage on the second data terminal, D- is an
`attribute of the power source, in this example. This is illus
`trated in FIG. 4B, where the dashed vertical line indicates the
`
`LGE-1013 / Page 12 of 15
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`

`US 2008/0272741 A1
`
`Nov. 6, 2008
`
`time where the cable is connected between the power source
`and mobile device, and the dashed lines on the D-- and D
`terminals indicate the signal transitions if the D- cable is
`connected to the pull up resistor. Table 1 illustrates a truth
`table
`
`TABLE 1.
`
`Truth Table, Signals vs. Upstream Power Source
`
`Upstream Power Source
`
`Signals
`
`AC Adapter
`
`PC USB Port
`
`EN for the 1.5 kg 5%
`pull up resistor
`D-
`D-
`
`1
`
`1
`1
`
`1
`
`1.O
`Of1
`
`0044 FIG. 5 illustrates a battery charging system accord
`ing to one embodiment of the present invention. This example
`illustrates an integrated circuit that may be included on an
`electronic device and used to charge a battery using the tech
`niques described above. An electronic device 500 may
`include a USB socket 509 for receiving a USB cable. The
`USB cable may include a ground connection (GND), a DC
`voltage (VBUS), and two data lines (D+ and D-). Socket 509,
`therefore, includes a ground connection, input Voltage con
`nection, and two data connections. In some applications, an
`AC to DC wall adapter may provide a USB compatible output
`including the four above mentioned outputs. Since a wall
`adapter may not provide data outputs, the D+ and D-termi
`nals may be connected together (i.e., short circuited) as illus
`trated by 590. In other applications, a USB port power source
`(e.g., a USB host or hub) may provide a USB compatible
`output including the four above mentioned outputs. Embodi
`ments of the invention detect the type of power source and
`may be used to configure a battery charger, for example.
`0045. In this example, the electronic device may include a
`USB controller 501 coupled to the USB socket for receiving
`VBUS, GND, D+, and D-. USB controller may couple data
`between integrated circuit 502 to a USB host or hub control
`ler, for example. In this example, the USB controller acts as an
`interface circuit. The USB controller 501 may include a
`power source detection circuit 561 as describe above. In one
`embodiment the controller 501 may include an internal pull
`up resistor. The pull up resistor may be selectively coupled to
`the D+ input terminal of the controller or the D- input termi
`nal of the controller. If a USB power source is provided to
`socket 509, controller 501 may detect the power and/or
`ground lines and generate an enable signal after a time period.
`The enable signal may couple an internal resistor in the con
`troller to the D-- or D-lines as described above. If the socket
`509 is coupled to an AC adapter with D+ and D-shorted
`together, then the voltage on both the D+ and D- terminals
`will increase. This state may be sensed and used to indicate
`that the power source is a dedicated charging power Source
`Such as an AC adapter (e.g., a USB adapter). A characteristic
`of the power source may correspond to a type of power
`conversion employed by the power source. Alternatively, if
`the socket 509 is coupled to an USB port with D+ and D
`coupled to ground through separate pull down resistors, then
`the voltage on the D+ and D-terminals will be different. One
`of the terminals will be pulled to ground through the pull
`down resistor, and the other terminal will be pulled up
`
`through the pull up resistor. This state may be sensed and used
`to indicate that the power source is a USB port.
`0046. In this example, integrated circuit 502 includes an
`input terminal (e.g., a package pin DCIN) for receiving the
`power source voltage VBUS, with a DC capacitor 510
`coupled between DCIN and ground. Integrated circuit 502
`includes a charge controller 503 for implementing switching
`regulation and battery charging algorithms. Controller 503
`may include data storage 550 (e.g., volatile or nonvolatile
`memory) for storing one or more values used to configure the
`charger, for example. Integrated circuit 502 further includes
`digital pins SDA and SCL for communicating information
`with USB controller 501 for programming and configuring
`the integrated circuit. For example, the USB controller may
`generate one or more signals that are received by charger 502
`that correspond to the power source. The USB controller may
`signal the charger that the power Source is an AC adapter, and
`may configure the charger to produce a first current or current
`sequence. Alternatively, the USB controller may signal the
`charger that the power source is a USB port power source, and
`may configure the charger to produce a second current or
`current sequence that uses less current than the first current or
`current sequence. The digital controller 504 may receive
`information from USB controller 501 and configure registers
`or other data storage elements in the integrated circuit to
`program the circuit to perform the desired functions, includ
`ing programming charge current levels, current limits, thresh
`old Voltages, or expected power source input Voltages, for
`example. In this example, controller 501 includes a power
`source detection circuit 561. Power source detection circuit
`561 may detect a short circuit between the D+ and D-USB
`lines as illustrated by 590, which may be used in wall adapters
`where no data is transmitted, as described above. If a short
`circuit is detected, integrated circuit 502 may operate in a first
`charging mode by programming a plurality of registers with
`charging parameters corresponding to a wall adapter power
`Source. If a short circuit is not detected (i.e., if an open circuit
`is detected), integrated circuit 502 may operate in a second
`charging mode by programming a plurality of registers with
`charging parameters corresponding to a USB power source.
`For example, in a USB power Source mode, the system may
`be configured with charge parameters based on information
`communicated between a USB host or hub controller and the
`integrated circuit controller 504 through USB controller 501,
`for example.
`0047. In this example, the regulator is a switching regula
`tor. Accordingly, integrated circuit 502 includes a first switch
`ing transistor 506 coupled between the DCIN pin and a
`switching output pin SW. A second switching transistor 507
`may be coupled between the SW pin and a ground pin GND
`for establishing a ground connection. The gates of Switching
`transistors 506 and 507 are coupled to the controller 503 for
`receiving Switching signals. Such as pulse width modulation
`(PWM), for example. The switching output pin is coupled
`to an inductor 512 and capacitor 514, which forms a filter. In
`this example, integrated circuit 502 further includes a current
`sense input pin CSIN coupled to the output of the filter. CSIN
`pin is coupled through a resistor 508 to a current sense output
`pin CSOUT. First and second terminals of resistor 508 are
`coupled to charge controller 503, and in accordance there
`with, controller 503 may detect the output current of the
`regulator. CSOUT pin is coupled to battery 513, which in this
`example is a 1 cell lithium ion (Li-ion) battery, and to other
`system electronics of the electronic device. The output cur
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`US 2008/0272741 A1
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`Nov. 6, 2008
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`rent, which is also the charge current in this example, may be
`set to an initial value based on the detected power Source and
`the battery charge circuit enabled. If the battery source is an
`AC adapter, the output current