United States Patent [19J
`Theobald
`
`I lllll llllllll Ill lllll lllll lllll lllll lllll 111111111111111111111111111111111
`US005925942A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,925,942
`Jul. 20, 1999
`
`[54] POWER SUPPLY CONTROL APPARATUS
`AND METHOD SUITABLE FOR USE IN AN
`ELECTRONIC DEVICE
`
`Theobald, "Battery Identification Apparatus and Associated
`Method", U.S.S.N. 08/572,837, filed Dec. 14, 1995, Atty.
`Docket CE01032R.
`
`[75]
`
`Inventor: David J. Theobald, Woodstock, Ill.
`
`[73] Assignee: Motorola, Inc., Schaumburg, Ill.
`
`[21] Appl. No.: 08/895,390
`
`[22] Filed:
`
`Jul. 16, 1997
`
`Int. Cl.6
`........................................................ H02J 7/00
`[51]
`[52] U.S. Cl. ............................ 307/125; 307/66; 455/573;
`320/137
`[58] Field of Search ................................ 307/125, 64, 66;
`455/90, 573; 320/106, 110, 137
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,843,299
`5,237,257
`5,254,931
`5,313,661
`5,315,228
`5,333,176
`5,418,445
`5,506,490
`5,519,303
`5,668,462
`5,764,026
`
`6/1989 Hutchings ................................. 320/31
`8/1993 Johnson et al. ............................. 320/2
`10/1993 Martensson . ... .... ... ... ... ... ... .... ... . 320/22
`5/1994 Malmi et al. .
`5 /1994 Hess et al. . .... ... ... ... ... ... .... ... ... .. 320/31
`7/1994 Burke et al. ............................ 455/573
`5 /1995 Alpert et al. ... ... ... ... ... .... ... ... ... .. 307 /66
`4/1996 DeMuro .................................. 320/106
`5/1996 Goedken et al.
`......................... 320/35
`9/1997 Hansson .................................. 320/110
`6/1998 Issa ......................................... 320/137
`
`FOREIGN PATENT DOCUMENTS
`
`2 239 567
`
`7/1991 United Kingdom .
`
`OIBER PUBLICATIONS
`
`Johnson et al., "Battery Charger Charging Time Control",
`U.S.S.N. 08/718,797, filed Sep. 24, 1996, Atty. Docket
`CE01931R.
`
`Alberth Jr. et al., "Electronic Device Having Internal Charge
`Regulator and Temperature Sensor for Controlling Applica(cid:173)
`tion of a Charging Current Thereto ... ", filed Sep. 13, 1993,
`U.S.S.N. 08/120,509, Atty. Docket CE00861R.
`
`Motorola Product List Web Page, Motorola Original Adapt(cid:173)
`ers, Personal Cellular Phone Adapters, p. 1, 1997.
`
`Motorola Product List Web Page, Motorola Original Hands
`Free Systems, Personal Cellular Phone Hands Free Solu(cid:173)
`tions, p. 1, 1997.
`
`Motorola Product List Web Page, Motorola Original Charg(cid:173)
`ers, Personal Cellular Phone Chargers, pp. l& 2, 1997.
`
`Primary Examiner-Albert W. Paladini
`Attorney, Agent, or Firm-Mark D. Patrick
`
`[57]
`
`ABSTRACT
`
`A power supply control apparatus (113) for an electronic
`device (102) includes a terminal (115) to couple to a battery
`(103), a connector (122) to couple to an external power
`supply (172), a switch circuit (140) coupled to the terminal
`(115) and the connector (122), and a controller (108)
`coupled to the switch circuit (140). The switch circuit (140)
`connects the terminal (115) to power the electronic device
`(102) from the terminal (115) when the battery (103) is
`attached and disconnects the terminal (115) to power the
`electronic device (102) from the connector (122) when the
`external power supply (172) is attached. The controller (108)
`selectively controls the switch circuit (140) to connect the
`connector (122) to the terminal (115) so as to charge the
`battery (103) from the external power supply (172).
`
`20 Claims, 2 Drawing Sheets
`
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`
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`
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`
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`
`RECEIVER
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`
`BASE
`
`101 ,.__........_____,
`
`ZTE/SAMSUNG 1005-0002
`IPR2018-00276
`
`

`

`U.S. Patent
`
`Jul. 20, 1999
`
`Sheet 2 of 2
`
`5,925,942
`
`ST ART
`
`......---.<:
`
`F IG.2
`
`READ VOLT AGE
`ON AUDIO
`IN LINE
`
`IDENTIFY ACCESSORY
`AS MID RATE CHARGER
`
`IDENTIFY ACCESSORY
`AS FAST RATE CHARGER
`
`NO
`
`SEND CHARGER
`ENABLE SIGNAL
`TO CONTROL SWITCH
`
`ZTE/SAMSUNG 1005-0003
`IPR2018-00276
`
`

`

`5,925,942
`
`1
`POWER SUPPLY CONTROL APPARATUS
`AND METHOD SUITABLE FOR USE IN AN
`ELECTRONIC DEVICE
`
`FIELD OF THE INVENTION
`
`This invention relates generally to electronic devices and,
`more particularly, to an apparatus and method used by an
`electronic device for controlling power supplied thereto.
`
`BACKGROUND OF THE INVENTION
`
`Electronic devices, such as cellular telephones, must be
`supplied with power in order to operate. A detachable battery
`is used to supply power to the device, particularly when
`portability of the device is desired. The battery is secured to
`the device via a battery connector. The battery supplies
`power to the device until depletion occurs. Once depleted,
`the battery must be replaced or recharged if portable opera(cid:173)
`tion of the device is to continue. If no replacement battery
`is available and portability is not a concern, operation of the
`device may be continued by attaching an accessory to the
`device.
`Accessories are attached to the device via an accessory
`connector of the device, such as the standardized eight pin
`13-type accessory connector used in MicroTAC™ cellular
`telephones manufactured and sold by Motorola, Inc. from
`1989 to the present. The 13-type accessory connector has an
`external power supply pin; an audio in pin; an audio out pin;
`data pins for high speed data communications according to
`the three-wire bus protocol used in radiotelephone products
`by Motorola, Inc.; and two grounding pins in a predeter(cid:173)
`mined arrangement. To be compatible with the 13-type
`accessory connector, an accessory must have a connector
`that is designed to mate with the accessory connector and
`have the same number and arrangement of pins. Upon
`attachment of the accessory to the device, the battery is
`electrically disconnected by an internal switch arrangement
`employed by the device and the device is powered solely by
`the accessory, which couples power transformed from an
`automobile electrical system or a conventional wall socket
`to the external power supply pin.
`Unfortunately, because the battery is disconnected upon
`attachment of the accessory, charging of the battery can not
`be accomplished via the accessory connector as described.
`In the past, charging of the battery was performed by
`detaching the battery from the battery connector of the
`device and placing it in a standalone charger or by providing
`a dedicated charger connector on the device separate from,
`and in addition to, the accessory connector and the battery
`connector that fed a current source circuit disposed in the
`device. The standalone charger lacked portability, while the
`dedicated charger connector and current source circuit added
`cost and complexity to the device. Therefore, what is needed
`is a low cost apparatus and method that permits charging of
`the battery by the device and maintains backward compat(cid:173)
`ibility with past accessories that mate with the accessory
`connector of the device.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 illustrates, in partial block and partial schematical
`diagram form, a charging system including an electronic
`device having a power supply control apparatus, a battery,
`and an accessory; and
`FIG. 2 illustrates, in flow chart form, a power supply
`control method implemented by the electronic device of
`FIG. 1.
`
`30
`
`2
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`A power supply control apparatus for an electronic device
`includes a terminal to couple to a battery, a connector to
`5 couple to an external power supply, a switch circuit coupled
`to the terminal and the connector, and a controller coupled
`to the switch circuit. The switch circuit connects the terminal
`to power the electronic device from the terminal when the
`battery is attached and disconnects the terminal to power the
`10 electronic device from the connector when the external
`power supply is attached. The controller selectively controls
`the switch circuit to connect the connector to the terminal so
`as to charge the battery from the external power supply. By
`using the external power supply, previously used only to
`15 power the electronic device, to also charge the battery, a low
`cost and backwards compatible charging system is realized.
`FIG. 1 illustrates a charging system 100. The charging
`system 100 includes an electronic device 102, a battery 103,
`and an accessory 104. The electronic device 102 commu-
`20 nicates with a base station 101, which provides wireless
`communications and features, such as paging, telephone,
`and short messaging, or the like, to the electronic device 102
`when it is located within a geographic area served by the
`base station 101. The base station 101 and the electronic
`25 device 102 communicate with each other via a communi(cid:173)
`cation link, which is preferably radio frequency (RF) signals
`105. In the illustrated embodiment, the electronic device 102
`is a cellular telephone and the base station 101 is a cellular
`telephone service provider.
`The electronic device 102 includes an antenna 106, a
`receiver 107, a controller 108, a memory 109, a speaker 110,
`a microphone 111, and a transmitter 112. The controller 108
`includes a microprocessor, such as a 68HC11 microproces-
`35 sor commercially available from Motorola, Inc., known
`synthesizer circuitry, and known audio logic circuitry. The
`controller 108 controls the operation of the electronic device
`102 according to instructions read from the memory 109.
`The antenna 106 detects and emits the RF signals 105. The
`40 receiver 107 operates under control of the controller 108 to
`convert signals received by the antenna 106 into data signals
`input to the controller 108 for use thereby and into voice
`signals input to the controller 108 for output by the speaker
`110 as audible speech. The transmitter 112 operates under
`45 control of the controller 108 to convert signals, which
`include data signals generated by the controller 108 and
`voice signals generated by the controller 108 from audible
`speech input via the microphone 111, for emission by the
`antenna 106.
`The electronic device 102 has a power supply control
`apparatus 113 that includes, aside from the controller 108, a
`supply terminal (B+) 114, battery terminals 115, 116, and
`117, a connector 122, and a switch circuit 140. The supply
`terminal 114 supplies power to electrical circuitry of the
`55 electronic device 102, including but not limited to, the
`receiver 107, the controller 108, and transmitter 112 via
`electrical connections (not shown).
`The battery terminals 115-117 are for electrically con(cid:173)
`necting to the battery 103. Battery terminals 115 and 116 are
`60 monitored by the controller 108 via lines 118 and 119.
`Battery terminal 117 is coupled to an analog ground 120 of
`the electronic device 102.
`The connector 122 is for physically and electrically
`connecting to the accessory 104. The connector 122 has
`65 multiple pins including information pins 124, 125, 127, 128,
`and 129 designated AUD IN, AUD OUT, and R, C, and T
`DATA, respectively; grounding pins 126 and 131 designated
`
`50
`
`ZTE/SAMSUNG 1005-0004
`IPR2018-00276
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`

`

`5,925,942
`
`3
`ANL GND and LOG GND; and an external power supply
`pin 130 designated EXT B+. The information pin 124 is
`coupled to the controller 108 via audio in line 132 and an
`identification network 150. The identification network 150 is
`employed to identify the accessory 104. In the illustrated 5
`embodiment, the identification network 150 includes a resis-
`tor 151, having a value of 15 kQ, coupled in series with the
`information pin 124 and the audio in line 132 and a resistor
`152, having a value of 15 kQ, coupled to the audio in line
`132 and the analog ground 120 in a shunt configuration, 10
`which give the identification network 150 an impedance of
`approximately 30 kQ looking in from the information pin
`124. The information pin 125 is coupled to the controller 108
`via audio out line 133. The information pins 127-129 are
`coupled to the controller 108 via data lines 134--136. The 15
`grounding pins 126 and 131 are coupled to the analog
`ground 120 and to a logic ground of the controller 108 via
`line 137, respectively. The external power supply pin 130 is
`coupled to the supply terminal 114 via a diode 138. The
`external power supply pin 130 is monitored by the controller 20
`108 via line 139. The connector 122 is preferably the
`standardized eight pin 13-type accessory connector
`employed by MicroTAC™ cellular telephones manufac(cid:173)
`tured and sold by Motorola, Inc. from 1989 to the present,
`but may be any other suitable multiple pin accessory con- 25
`nectar having an external power supply pin and at least one
`information pin.
`The switch circuit 140 selectively connects the battery
`terminal 115 to the supply terminal 114. The switch circuit
`140 includes a mechanical switch 141, a transistor switch 30
`142, and a control switch 143. The mechanical switch 141
`is coupled to the connector 122, the supply terminal 114, and
`the battery terminal 115. The mechanical switch 141 elec(cid:173)
`trically connects the supply and battery terminals 114 and
`115 when the connector 122 is unattached and opens to 35
`electrically disconnect the supply and battery terminals 114
`and 115 when the accessory 104 is physically attached to the
`connector 122.
`The transistor switch 142 is coupled in parallel with the
`mechanical switch 141 to prevent interruption of power to 40
`the electronic device 102 when the mechanical switch 141 is
`opened or closed. The transistor switch 142 provides a
`conduction path between the supply and battery terminals
`114 and 115 until a voltage level at the supply terminal 114
`meets or exceeds a voltage level at the battery terminal 115
`causing the transistor switch 142 to turn off. The transistor
`switch 142 is preferably a MOSFET (metal-oxide semicon(cid:173)
`ductor field effect transistor) having gate and drain terminals
`coupled to the supply terminal 114, a source terminal
`coupled to battery terminal 115, and an intrinsic diode
`coupled across the source and drain terminals. One skilled in
`the art will recognize that the mechanical switch 141 in the
`aforementioned arrangement is redundant and the desired
`switching of the supply and battery terminals 114 and 115
`can be accomplished using only the transistor switch 142.
`The control switch 143 is coupled to the transistor switch
`142 and the controller 108 via line 144 to selectively control
`the transistor switch 142. In response to an enable signal on
`line 144, the control switch 143 turns on and pulls the gate
`of the transistor switch 142 low, which in turn forces the 60
`transistor switch 142 to turn on and provide a current
`conduction path between the supply and battery terminals
`114 and 115. The control switch 143 is preferably a BJT
`(bipolar junction transistor) having a collector terminal
`coupled to the gate of the transistor switch 142, a base 65
`coupled to the controller 108 via line 144, and an emitter
`coupled to the analog ground 120.
`
`4
`Although electronic device 102 is illustrated as a cellular
`telephone, the present invention will also find application in
`radios, portable computers, cordless telephones, two-way
`radios, pagers, personal digital assistants, tape recorders, and
`the like, and "electronic device" as used herein shall refer to
`all such battery powered electronic devices and their equiva-
`lents.
`The battery 103 includes an electrochemical cell 160, a
`thermistor 161, and contacts 162-164. The electrochemical
`cell 160 includes a positive polarity terminal 165 coupled to
`contact 162 and a negative polarity terminal 166 coupled to
`contact 164. The electrochemical cell 160 is preferably
`rechargeable, and can be, for example, any one of the
`following chemical types: Nickel-Cadmium (NiCd), Nickel(cid:173)
`Metal Hydride (NiMH), Alkaline, or Lithium Ion. In the
`illustrated embodiment, the electrochemical cell 160 sup(cid:173)
`plies a battery voltage supply, preferably of 6 V DC (direct
`current), at the positive polarity terminal 165. The thermistor
`161 is coupled to the contacts 163 and 164. A voltage level
`across the thermistor 161 forms a temperature signal corre(cid:173)
`sponding to the temperature of the electrochemical cell 160.
`The accessory 104 has a plug 171, a transformer and
`regulator 172, a connector 173, and an identification element
`174. The accessory 104 can be a modem, a hands-free car
`kit, a battery saver, or the like, and include accessory
`circuitry 170. The accessory circuitry 170 can include a
`microprocessor requiring a logic ground; and data or audio
`input/output devices such as a keypad, a microphone, or a
`speaker requiring a connection to an analog ground 175 of
`the accessory 104. However, in the illustrated embodiment,
`the accessory 104 is a low cost mid rate charger or fast rate
`charger that does not include the accessory circuitry 170.
`The plug 171 is compatible to mate with a conventional
`wall outlet (not shown) and provide external power (e.g.,
`110 V AC (alternating current) supply) to the accessory 104
`from the outlet. Alternatively, the plug 171 could be com(cid:173)
`patible to mate with a cigarette lighter port to provide power
`to the accessory 104 from an automobile electrical system,
`or with another suitable power supply.
`The transformer and regulator 172 is coupled to the plug
`171 and has conventional circuitry. The transformer and
`regulator 172 provides an external power supply to connec(cid:173)
`tor 173 via line 176. In the illustrated embodiment, the
`45 external power supply is a current limited constant voltage
`supply supplying an 8.6 V DC output voltage for both the
`mid and fast rate chargers, a 340 mA current for the mid rate
`charger, and a 850 mA current for the fast rate charger. The
`transformer and regulator 172 preferably includes a tracking
`50 circuit that adjusts output power according to feedback
`received on line 176. In the event that the accessory 104 has
`the accessory circuitry 170, the transformer and regulator
`172 outputs regulated power on line 177 to power the
`accessory circuitry 170. The transformer and regulator 172
`55 is coupled to the analog ground 175.
`The connector 173 is for physically and electrically
`connecting to the connector 122 of the electronic device 102.
`The connector 173 has multiple pins including information
`pins 179, 180, 182, 183, and 184 designated AUD OUT,
`AUD IN, and R, C, and T DATA, respectively; grounding
`pins 181and186 designated ANL GND and LOG GND; and
`an external power supply pin 185 designated EXT B+. The
`information pins 179 and 180 are coupled to an audio out
`line 187 and an audio in line 188, respectively. The infor(cid:173)
`mation pins 181-183 are coupled to data lines 190-192. The
`grounding pins 181 and 186 are coupled to the analog
`ground 175 and logic ground line 193, respectively. The
`
`ZTE/SAMSUNG 1005-0005
`IPR2018-00276
`
`

`

`5,925,942
`
`10
`
`5
`external power supply pin 185 is coupled to the transformer
`and regulator 172 via line 176.
`The identification element 174 is employed to identify the
`accessory 104 to the electronic device 102. The identifica(cid:173)
`tion element 174 has two ends, one end coupled to line 176
`and the other end coupled to the audio out line 187. The
`identification element 174 is selected to have a different
`electrical value for each different type of the accessory 104.
`For example, in the illustrated embodiment, the identifica(cid:173)
`tion element 174 employed in the mid rate charger accessory
`is a 120 kQ resistor, and the identification element 174
`employed in the fast rate charger accessory is a 36 kQ
`resistor.
`The charging system 100 operates according to a power
`supply control method shown in FIG. 2. Steps of the method
`of FIG. 2 are stored in the memory 109 of FIG. 1 as
`instructions, which are executed by the controller 108 in the
`following manner.
`Referring to FIGS. 1 and 2, the controller 108 waits until
`the battery 103 is attached to the electronic device 102 (at
`step 200). The battery 103 is attached to the electronic
`device 102 when the contacts 162-164 of the battery 103 are
`physically mated with, and electrically connected to, the
`battery terminals 115-117, respectively. Upon attachment of
`the battery 103, the positive polarity terminal 165 of the
`electrochemical cell 160 is electrically connected to the
`supply terminal 114 and the electronic device 102 is pow(cid:173)
`ered by the battery voltage supply. The controller 108
`detects attachment of the battery 103 from the presence of
`the battery voltage supply on line 118. The diode 138
`prevents the power supplied by the battery 103 from drain(cid:173)
`ing out the connector 122. The electronic device 102 is
`powered from the battery 103 until it discharges to a voltage
`level that is insufficient to operate electronic device 102.
`Next, the controller 108 waits until the accessory 104 is
`attached to the electronic device 102 (at step 201). The
`accessory 104 is attached to the electronic device 102 when
`the connectors 173 and 122 are physically mated so that the
`pins 179-186 and 124-131, respectively, are held in elec(cid:173)
`trical contact. The mechanical switch 141 of the switch
`circuit 140 opens upon physical mating of the connectors
`122 and 173. The transistor switch 142 of the switch circuit
`140 turns off when the external power supply is supplied to
`the supply terminal 114 from the transformer and regulator
`172 via the path of line 176, the pins 185 and 130, and the
`diode 138. The transistor switch 142 turns off because, in the
`illustrated embodiment, the voltage level of the external
`power supply at the supply terminal 114 is approximately
`7.8 V after passing through the diode 138, which exceeds the
`battery supply voltage of approximately 6 V at the battery
`terminal 115. The controller 108 senses attachment of the
`accessory 104 from the presence of the external power
`supply on line 139. Once the mechanical switch 141 is open
`and the transistor switch 142 is off, the electrochemical cell 55
`160 of the battery 103 is disconnected from the supply
`terminal 114 and the electronic device 102 is powered by the
`external power supply of the accessory 104.
`Also upon attachment of the accessory 104, the identifi(cid:173)
`cation element 174 of the accessory 104 is electrically
`connected to the identification network 150 of the electronic
`device 102 via the pins 179 and 124, and the analog grounds
`175 and 120 are intercoupled via pins 181 and 126. The
`external supply voltage of the accessory 104, which is
`coupled to the identification element 174 via line 176, drives
`the identification element 174 and the identification network
`150 to generate a voltage level on the audio in line 132 of
`
`6
`the electronic device 102. In the illustrated embodiment, a
`voltage level of approximately 1.72 V is generated on the
`audio in line 132 when the mid rate charger accessory is
`attached and a voltage level of approximately 3.91 V is
`5 generated on the audio in line 132 when the fast rate charger
`accessory is attached. If the accessory 104 has the accessory
`circuitry 170, audio is communicated between the accessory
`circuitry 170 and the controller 108 via the path of audio out
`line 187-pin 179-pin 124-audio in line 132 and the path of
`audio out line 133-pin 125-pin 180-audio in line 188; data is
`communicated between the accessory circuitry 170 and the
`controller 108 via the path of data line 190-pin 181-pin
`127-data line 134, the path of data line 191-pin 182-pin
`128-data line 135, and the path of data line 192-pin 184-pin
`129-data line 136 according to the three-wire bus protocol
`15 utilized in radiotelephone products manufactured and sold
`by Motorola, Inc. or other suitable high speed data commu(cid:173)
`nication protocol; and the logic grounds are intercoupled via
`lines 193 and 137 and pins 186 and 131.
`Once the accessory 104 is attached, the controller 108
`20 measures the voltage level on the audio in line 132 (at step
`202). Next, the controller 108 compares the voltage level on
`the audio in line 132 to voltage level ranges stored in an
`accessory lookup table in the memory 109 (at steps 204 and
`206). The accessory lookup table also contains an accessory
`25 identity associated with each voltage level range. In
`particular, the controller 108 determines if the voltage level
`on the audio in line 132 falls within a first voltage level range
`defined by voltage level Vl and voltage level V2, which are
`preferably approximately 1.6 V and approximately 1.9 V,
`30 respectively (at step 204). If the voltage level on the audio
`in line 132 falls within the first voltage level range, the
`controller 108 identifies the accessory 104 from the acces(cid:173)
`sory lookup table as a mid rate charger (at step 208).
`If the voltage level on the audio in line 132 does not fall
`35 within the first voltage level range, the controller 108
`determines if the voltage level on the audio in line 132 falls
`within a second voltage level range defined by voltage level
`V3 and voltage level V4, approximately 3.6 V and approxi(cid:173)
`mately 4.2 V, respectively (at step 206). If the voltage level
`40 on the audio in line 132 falls within the second voltage level
`range, the controller 108 identifies the accessory 104 from
`the accessory lookup table as a fast rate charger (at step 210).
`If the voltage level on the audio in line 132 does not fall
`within the second voltage level range, the controller 108
`45 ends the method (at step 212).
`The accessory lookup table is described above as only
`containing voltage level ranges and identities associated
`with two accessories. However, one skilled in the art will
`recognize that the accessory lookup table could be made
`50 larger to contain additional voltage level ranges and acces(cid:173)
`sory identities, and that the method of FIG. 2 could be easily
`modified such that the controller 108 continues to traverse
`the larger lookup table following step 206 and prior to
`ending the method at step 212.
`Although the aforementioned identification scheme is
`preferred because it eliminates the need for, and the cost of,
`the accessory circuitry 170, one skilled in the art will
`recognize that alternative ways of identifying the accessory
`104 to the electronic device 102 could be employed without
`60 altering the connectors 122 and 173. For example, the mid
`or fast rate chargers could be implemented with a logic
`circuit or a microcontroller that communicates predefined
`identification information to the controller 108 via the data
`lines 190--192 and pins 182-184 upon attachment of the
`65 accessory 104.
`Next, the controller 108 determines if the voltage and the
`temperature of the battery 103 are within a predetermined
`
`ZTE/SAMSUNG 1005-0006
`IPR2018-00276
`
`

`

`5,925,942
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`5
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`10
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`7
`range for charging the battery 103 at a mid rate (at step 218)
`or a fast rate (at step 220). The controller 108 determines if
`a voltage level of the battery voltage supply measured on
`line 118 falls within a suitable charging voltage range stored
`in the memory 109, such as the voltage range of approxi-
`mately 5.8 V to approximately 7.8 V. The controller 108 also
`determines if a temperature level of the battery 103 indicated
`by the temperature signal measured on line 119 falls within
`a suitable charging temperature range stored in the memory
`109, such as the temperature range of approximately 5° C.
`to 40° C.
`If the voltage level and the temperature level fall within
`suitable ranges, the controller 108 initiates charging of the
`battery 103 at the mid or fast rate by placing an enable signal
`on line 144 (at step 214). The enable signal drives the control 15
`switch 143 to turn on the transistor switch 142 and conduct
`current supplied by the external power supply at the supply
`terminal 114 to the electrochemical cell 160 of the battery
`103 via the battery terminal 115. The current supplied by the
`external power supply at the mid or fast rate charges the 20
`battery 103. The controller 108 maintains the enable signal
`on the line 144 as long as the battery 103 remains within the
`voltage and temperature range at step 214 and is determined
`to be not fully charged (at step 218). In the illustrated
`embodiment, the controller 108 determines that the battery 25
`103 is fully charged when the temperature of the battery 103
`exceeds 45° C. Once the battery 103 is fully charged, the
`controller 108 ends the method (at step 212).
`By using the AUD OUT and IN information pins 179 and
`124 and audio out and in lines 187 and 132 to communicate 30
`the identity of the accessory 104 to the electronic device
`102, the accessory identification system 100 remains back(cid:173)
`wards compatible with other previous accessories of the
`electronic device 102 that attach to the connector 122. For
`example, attachment of the Original Ultra Saver accessory 35
`manufactured and sold by Motorola, Inc. as model number
`SLN9739, to the connector 122 generates a 0 V voltage level
`on the audio in line 132 that is not within the voltage level
`ranges of the aforementioned mid and fast rate chargers.
`Also, attachment of the Zero Install Hands-Free Adapter 40
`accessory manufactured and sold by Motorola, Inc. as model
`number SLN3595, to the connector 122 generates an 8 V
`voltage level on the audio in line 132 that is not within the
`voltage level ranges of the aforementioned mid and fast rate
`charger accessories.
`Use of the identification element 174 and the identifica(cid:173)
`tion network 150 to identify the accessory 104 to the
`electronic device 102 is not limited to those accessories that
`do not output/receive audio to/from the electronic device
`102 (i.e., the mid and fast rate chargers described above).
`For example, a hands-free accessory, which continually
`supplies microphone audio signals for the electronic device
`102 via the path of audio out line 187-pin 179-pin 124-audio
`in line 132, could employ, for example, a 11.2 kQ resistor as
`the identification element 174. The 11.2 kQ resistor in 55
`conjunction with the identification network 150 having the
`30 kQ impedance generates a voltage level of approximately
`5.7 Vat the audio in line 132. The microphone audio signals
`generated by the hands-free accessory become modulated on
`the voltage level at the audio in line 132. The controller 108 60
`filters the modulated signal to extract the audio signals for
`use in operating the electronic device 102 and the voltage
`level for use in identifying the accessory 104.
`Thus, it can be seen that a power supply control apparatus
`and method can be implemented that permits reuse of the 65
`external power supply of an accessory, previously used only
`to power an electronic device, to charge a battery of the
`
`8
`electronic device. By reusing the external power supply in
`this manner, the electronic device effectively operates as a
`mid or fast rate charger without the added cost and com(cid:173)
`plexity of an internal current source circuit used by prior art
`electronic devices to perform charging. Also, by reusing the
`external power supply, a dedicated charger interface to the
`electronic device as well as modification of the existing
`accessory connector can be avoided, thereby maintaining
`backwards compatibility with existing accessories.
`What is claimed is:
`1. A power supply control apparatus for an electronic
`device, the apparatus comprising:
`a supply terminal to provide power to the electronic
`device;
`a battery terminal to couple to a battery;
`an accessory connector to couple to an accessory, the
`accessory connector having a plurality of pins, one of
`the plurality of pins being an external power supply pin
`coupled to the supply terminal