Background of the Invention

The present invention relates generally to electronic devices which may be powered by rechargeable power supplies and, more particularly, to an electronic device, and an associated method, connectable to an external power source capable of providing operative power to power an electronic device and also to recharge a rechargeable power supply of the electronic device. Many electronic devices are constructed of designs which permit powering thereof by a battery comprised of one or more battery cells. In some instances, use of a battery power supply to power the electronic device is necessitated when the electronic device is not, or cannot be, positioned proximate to a permanent, or other fixed, power supply. In other instances, a battery power supply is utilized to power the electronic device to increase the portability of the device as no power cable is required to interconnect the electronic device to the permanent, or other fixed, power supply. Typically, the one or more battery cells comprising the battery power supply utilized to power the electronic device are carried directly with, or housed within, the electronic device.

However, because a battery power supply is capable of storing only a finite amount of energy, powering of the electronic device with the battery power supply is limited by the energy storage capacity of the battery power supply. Powering of the electronic device by the battery power supply causes discharge of the stored energy of the battery power supply. Once the stored energy of the battery power supply is discharged beyond a certain level, replacement of the battery power supply is necessitated to permit continued operation of the electronic device. Increasing the energy storage capacity of a

battery power supply, such as by increasing the number of battery cells comprising such power supply, increases the size (and weight) of the power supply. Such manner of increasing the energy storage capacity of a battery power supply reduces the portability of the electronic device when the battery power supply is carried with the electronic device. Accordingly, when designing a battery power supply, a compromise is made between increased energy storage capacity and reduced portability of the electronic device which carries such a battery power supply. A portable or transportable radiotelephone is one such electronic device which is typically powered by a battery power supply. The battery power supply is typically carried directly with the radiotelephone and is of a size and weight which does not unduly constrain the portability of the radiotelephone. A radiotelephone includes radio transceiver circuitry including transmitter circuitry and receiver circuitry which is operative to transmit and to receive, respectively, modulated signals. In typical operation of a radiotelephone, receiver circuitry portions thereof are powered continuously while awaiting reception of signals indicative of an incoming call to the radiotelephone. Thereafter, the transmitter circuitry portions of the radiotelephone are also powered to permit transmission of modulated signals therefrom. .

Radiotelephones operative in many cellular communication systems are constructed to transmit modulated signals therefrom and also simultaneously to receive modulated signals transmitted thereto (the modulated signals transmitted by and to the radiotelephone are transmitted upon separate frequency channels). Radiotelephones operative in other cellular communication systems are constructed to transmit and to receive modulated signals during nonsimultaneous time periods and, during two-way communication with the radiotelephone, the receiver and transmitter circuitry portions are powered during nonsimultaneous time periods.

Times during which the receiver circuitry portions of the radiotelephone are powered while awaiting transmission thereto of signals indicative of an incoming call shall hereinafter be referred to

as times in which the radiotelephone is in the "standby" mode. (It should, of course, be noted that a user of a radiotelephone also oftentimes provides operative power to the radiotelephone only when the user desires to initiate and thereafter effectuate a telephone call; during other times no operative power is provided to the radiotelephone, and the radiotelephone is not powered to receive signals transmitted thereto. That is to say, the user of the radiotelephone may choose not operate the radiotelephone in the "standby" mode to receive an incoming call transmitted to the radiotelephone, but rather power the radiotelephone only during times in which the user initiates a telephone call.)

Generally, the amounts of energy required to operate the transmitter circuitry portions of the radiotelephone are greater than the amounts of energy required to operate the receiver circuitry portions thereof. And, because practical devices are of less than ideal efficiencies, a certain portion of the energy applied to the radiotelephone is converted into heat energy which results in heat build-up of the radiotelephone. As more energy is required to operate the transmitter circuitry portions of the radiotelephone, there is a correspondingly greater amount of heat generation during operation of the transmitter circuitry portions of the radiotelephone than when only the receiver circuitry portions are operable/

Rechargeable battery power supplies have been developed and are commercially available. Some of such commercially-available, rechargeable battery power supplies are of constructions designed for use to power radiotelephones. The use of rechargeable battery power supplies is advantageous as the rechargeable batteries may be recharged by applying a charging current generated by a power supply thereto. Once recharged, the rechargeable battery power supply may be reused. Some constructions of rechargeable battery power supplies may be recharged, and reused, up to, and even in excess of, five hundred times.

As mentioned previously, a battery power supply is typically comprised of one or more battery cells. The cells are connected in a series (or other) connection, and are typically housed within a

common housing. The housing, together with the battery cells, comprise the battery power supply which is also oftentimes referred to as a battery pack. For purposes of simplicity, such constructions are also generically referred to by the general term "battery". The present disclosure shall, at times, utilize such simplified terminology.

The battery cells of a rechargeable battery power supply are formed of various different materials of construction. For instance, a rechargeable battery cell may be comprised of a lithium (Li) material, a nickel-cadmium (Ni-Cd) material, or a nickel metal hydride (NiMHθ ₂ ) material. Battery cells constructed of these different materials exhibit different characteristics during charging thereof. Battery charging apparatus is also commercially available to permit recharging of rechargeable batteries. A battery charger comprising such battery charging apparatus is typically comprised of a power source for supplying operative power to recharge the rechargeable battery power supply when suitably connected to the charging apparatus to receive the operative power.

The energy of the operative power applied to the rechargeable battery power supply is converted into chemical energy which is stored by the rechargeable battery cells of the battery power supply. Application of the operative power to the battery .cells over an elapsed period of time permits the rechargeable battery cells to become fully recharged. Again, however, because practical devices are of less than ideal efficiencies, a certain portion of the energy applied to the battery cells are converted into heat energy which causes heat build¬ up of the battery cells.

Some battery charging apparatus are of construction-types which permit the electronic device and also the battery power supply both to receive operative power. Such battery charging apparatus provides operative power not only to recharge the rechargeable battery cells of the battery power supply but further provides operative power to permit operation of the electronic device.

For instance, battery charging apparatus of construction-types permitting a radiotelephone together with a rechargeable battery

pack to receive operative power to recharge the battery cells of the battery pack and also to permit operation of the circuitry of the radiotelephone is available. As mentioned previously, however, in practical devices, heat is generated as a byproduct of operation of the circuitry of the radiotelephone. And, heat is also generated as a byproduct of the process of recharging the battery cells of the battery power supply.

As also noted previously, greater amounts of energy are required to operate the transmitter circuitry portions of the circuitry of the radiotelephone. Because a portion of the operative power applied to the radiotelephone is converted into heat energy, and heat energy is also generated during recharging of the rechargeable battery cells of the battery pack, an excessive amount of heat build-up of the radiotelephone may occur when operative power is provided both to recharge the battery cells of the battery pack and also to operate portions of the circuitry of the electronic device, here the radiotelephone and particularly during times in which the transmitter circuitry portions of the radiotelephone are operable.

What is needed, therefore, is means by which operative power may be provided to an electronic device including a rechargeable power supply but which prevents excessive heat build-up as a result of application of the operative power to the electronic device.

Summary of the Invention

The present invention, accordingly, provides a device, and associated method, which overcomes the problems associated with the existing art.

The present invention further advantageously provides an electronic device including a rechargeable power supply wherein the electronic device is connectable to a variable-level power source which provides operative power to recharge the rechargeable power supply and also to provide operative power to operate electronic circuitry of the electronic device.

The present invention includes further advantages and features, the details of which will become more apparent upon reading the following detailed description of the preferred embodiments. In accordance with the present invention, therefore, a electronic device, and associated method, releasably connectable to a variable-level power source is disclosed. The electronic device is operable to receive operative power of either of at least two power levels generated by the variable-level power source. The electronic device comprises connecting elements which permit releasable connection with the variable-level power source. The connecting elements include at least a first connecting element and a second connecting element wherein the first connecting element permits connection of the variable-level power source to receive operative power thereat. A rechargeable power supply is coupled to receive a charging signal responsive to times in which the variable-level power source is connected to the first connecting element of the connecting elements and generates the operative power of a first power level of the either of the at least two power levels. Electronic circuitry is coupled to receive alternately either the operative power generated by the variable-level power source provided at the first connecting element or power generated by energy stored by the rechargeable power supply. Control circuitry is coupled to the electronic circuitry and is operative to generate a power-source control signal for application to the second connecting element of the connecting elements wherein the power-source control signal is of either of at least a first signal level to cause the operative power of the variable- level power source to be of a first of the at least two power levels or of a second signal level to cause the operative power of the variable level power source to be of a second of the at least two power levels.

Brief Description of the Drawings

The present invention will be better understood when read in light of the accompanying drawings in which: FIG. 1 is a block diagram of an electrical device of a preferred embodiment of the present invention connected to a variable-level power source;

FIG. 2 is a block diagram, similar to that of FIG. 1, but of a preferred embodiment of the present invention connected to a variable-level power source;

FIG. 3 is a partial block, partial circuit schematic diagram of a charge regulator which forms a portion of the electronic device of FIG. 1 and the radio transceiver of FIG. 2;

FIG. 4 is a schematic representation of a cellular radiotelephone, similar to the radio transceiver shown in block form in FIG. 3, of a preferred embodiment of the present invention; FIG. 5 is a flow diagram listing the method steps of an algorithm executable by control circuitry which forms a portion of the radio transceiver of FIG. 2 and the electronic device of FIG. 1; and FIG. 6 is a flow diagram listing the method steps of the method of a preferred embodiment of the present invention.

Description of the Preferred Embodiments

As mentioned hereinabove, a portable electronic device is oftentimes powered by a rechargeable power supply. When the rechargeable power supply is depleted of stored energy, battery charging apparatus is utilized to recharge rechargeable battery cells of the rechargeable power supply. Several constructions of battery charging apparatus are available which permit the portable electronic device to be positioned together with the rechargeable power source carried therewith such that operative power is provided both to the rechargeable battery cells of the rechargeable power supply and also to the circuitry of the electronic device.

However, because power transfer between the battery charging apparatus and the electronic device is not wholly efficient, a certain portion of the energy of the operative power generated by the battery charging apparatus is converted into heat energy which, during dissipation thereof, elevates the temperature of the electronic device. When operative power generated by the battery charging apparatus is utilized both to recharge the battery cells of the rechargeable power supply and also to operate the circuitry of the electronic device, heat energy is generated during operation of both processes. In the particular instance in which the electronic device comprises a radiotelephone operative in a cellular communication system, battery charging apparatus may be constructed to provide operative power to recharge the rechargeable battery cells of the rechargeable power supply carried with the radiotelephone while also providing operative power to permit operation of transmitter and receiver circuitry portions of the radiotelephone.

As mentioned hereinabove, greater amounts of power are required to operate transmitter circuitry portions of the radiotelephone than to operate receiver circuitry portions thereof. Hence, when a radiotelephone (or other radio transceiver) having a rechargeable power supply is positioned to recharge the battery cells of the rechargeable power supply and the radiotelephone is simultaneously operated, greater amounts of power are required during times in which the radiotelephone is operative to transmit modulated signals than during times in which the radiotelephone is operative only to receive modulated signals. (As also noted hereinabove, a radiotelephone is oftentimes operated in the "standby" mode in which only the receiver circuitry portions of the radiotelephone are operable while awaiting reception of modulated signals indicative of an incoming telephone call. Only during times in which two-way communication is to be, or is, effectuated between the radiotelephone and a remote location must the transmitter circuitry portion of the radiotelephone be operable.) Accordingly, because greater amounts of power are required during times in which the transmitter circuitry portions of the radiotelephone are

operated than during times in which only the receiver circuitry portions of the radiotelephone are operated, greater amounts of heat energy are produced during times in which the transmitter circuitry portions of the radiotelephone are operated. Battery charging apparatus operative to permit both recharging of the battery cells of the rechargeable power supply and also to power the circuitry of the electronic device must generate power at power levels permitting both such recharging and such operation. Battery charging apparatus operative to generate a charging signal of only a single power level must generate the signal to be of a power level permitting simultaneous recharging of the battery cells of the rechargeable battery power supply and also to operate the electronic circuitry of the electronic device. When the electronic device is not being operated, such battery charging apparatus generates a charging signal of the same power level as the power level of the charging signal generated when the circuitry of the electronic device is being operated. The power which would otherwise be utilized to power the circuitry of the electronic device is not utilized for any useful purpose and is, instead, converted into heat energy.

In the particular instance in which the electronic device comprises a radiotelephone, battery charging apparatus operative to permit both recharging of the battery cells of a rechargeable power supply carried with the radiotelephone and also to power the transceiver circuitry thereof may be constructed. But when such battery charging apparatus is operative to generate a charging signal of only a single power level, the power level must be great enough to permit, simultaneously, recharging of the battery cells of the rechargeable power supply and also operation of both the receiver circuitry portion and the transmitter circuitry portion of the radiotelephone.

While the receiver circuitry portion of the radiotelephone is oftentimes powered to be in the "standby" mode of operation, the transmitter circuitry portion is only powered during times in which two-way communication is to be effectuated with a remote site. As

the transmitter circuitry portion of the radiotelephone is operative only during times in which two-way communication is, or is to be, effectuated, in many instances, when the radiotelephone together with the rechargeable power supply is positioned to receive the charging signal generated by the battery charging apparatus operative to generate the charging signal of only a single power level, the radiotelephone is even more susceptible to overheating as excessive amounts of power are converted into heat energy.

Battery charging apparatus operative to generate a charging signal of a power level which is variable responsive to power requirements of the electronic device which carries the rechargeable battery source would be advantageous.

In the particular instance of the radio transceiver such as the radiotelephone, battery charging apparatus operative to prevent overheating of the transceiver when the transmitter circuitry portion thereof is operative would be particularly advantageous.

Turning first then to the block diagram of FIG. 1, an electronic device, referred to generally by reference numeral 10, of a preferred embodiment of the present invention is positioned in releasable connection with variable-level power source 16. Variable-level power source 16 is connected to electronic device 10 by way of lines 22 and 28, respectively, at connecting elements 34 and 40, here shown to be plug connectors represented by plug terminals enclosed by rectangles, indicated in dash. Variable-level power supply 16 may, in turn, be connected to a conventional household power supply (by way of connection with plug connector 36) or other suitable power supply.

Variable-level power source 16 is operative to generate a charging signal on line 22 which is of either of at least two separate power levels. (In a further embodiment of the present invention, power source 16 is operable to generate a charging signal on line 22 which is of any of many levels between a maximum and minimum charging level.)

Line 46 of electronic device 10 is coupled to receive the charging signal generated by variable-level power source 16 on line 22. Line 46, in turn, is coupled to electronic circuitry 52 of electronic device 10 to

provide operative power thereto when power source 16 is connected to connecting element 34 by way of line 22 to provide operative power thereto.

Line 46 is further coupled to charge regulator 58 which 5 regulates the value of the charging signal applied thereto on line 46 and generates a regulated, charging signal on line 64 which is coupled to rechargeable battery power supply 70. Power supply 70 is comprised of one or more rechargeable battery cells. Through such connection, the charging signal generated by power source 16 on line

10 22 is applied to rechargeable battery power supply 70 to recharge the rechargeable battery cells thereof.

The battery cells of rechargeable battery power supply 70 convert the energy of the charging signal generated by power source 16 and regulated by charge regulator 58 into chemical energy which

U5 is stored in the battery cells of the rechargeable battery power supply. Battery power supply 70 is coupled to electronic circuitry 52 by way of line 76. When power source 16 is not connected to electronic device 10 to apply a charging signal thereto, the stored energy of battery power supply 70 is utilized to power circuitry 52 to permit

20 operation of electronic device 10 thereby. Powering of circuitry 52 with the stored energy of battery power supply 70, however, and as noted hereinabove, discharges the stored energy of the battery power supply. Once the stored energy of battery power supply 70 is depleted beneath a certain level, the battery cells of the battery power supply

25 must be recharged by applying a charging current to the battery power supply to recharge the battery cells thereof.

Control circuitry 82 further forms a portion of electronic device 10. Control circuitry 82 is coupled to electronic circuitry 52 by way of line 88 and to charge regulator 58 by way of line 94. Control circuitry

30 82 is further coupled to connecting element 40 by way of line 100, thereby to permit connection of control circuitry 82 to line 28 which, in turn, is connected to variable-level power source 16. And, control circuitry 82 is also preferably coupled to rechargeable battery power supply 70 by way of line 106.

Electronic device 10 further includes input element 112 which is coupled to electronic circuitry 52 by way of line 118. Similarly, display element 124, comprised of, for example, light emitting diodes, is also coupled to electronic circuitry 52, here by way of line 128. A user of electronic device 10 operates device 10 by appropriate actuation of input element 112 (such as, for example, actuating an off/on actuation switches which may comprise portions of input element 112). Portions of electronic circuitry 52 operative responsive to such inputs connect circuit elements thereof to receive operative power on either line 46 which is generated by power source 16 when connected to device 10 by way of connecting element 34 or, otherwise, to battery power supply 70. When electronic circuitry 52 is operative, a signal indicative of such operation is supplied to control circuitry 82 by way of line 88. Responsive to the signal supplied thereto on line 88, control circuitry 82 generates a signal of a first signal value on line 100 which, in turn, is supplied to line 28 by way of connecting element 40 to be applied to variable-level power source 16 when connected to connecting element 40 by way of line 28. When, conversely, electronic circuitry 52 is not to be operated, a signal of a second signal value (or no signal) is generated on line 88 and applied to control circuitry 82. In such instances, control circuitry 82 generates a signal of a second signal level value (or no signal) on line 100 which similarly may be applied to variable-level power source 16. When variable-level power source 16 is connected to connecting element 40, power source 16 thereby receives a signal on line 28 indicating whether electronic circuitry 52 is being operated.

When electronic circuitry 52 is being operated and power source 16 is connected to electronic device 10, the charging signal generated by power source 16 on line 22 must be of a power level great enough to power circuitry 52. When, conversely, electronic circuitry 52 is not to be operable, power source 16 need not generate a charging signal of a power level to cause operation of circuitry 52.

As the charging signal generated by power source 22 is further utilized to recharge the battery cells of battery power supply 70, the

charging signal generated by power source 16 must be of a power level to recharge adequately the battery cells of the battery power supply. Charge regulator 58, operative to regulate the level of the charging signal generated by power source 16 on line 22 generates a 5 regulated charging signal on line 64 which is applied to the battery cells of battery power supply 70.

Control circuitry 82 is further operative to generate a control signal on line 94 to control the level of the regulated charging signal applied to the battery cells of the battery power supply. The value of 0 the control signal generated on line 94 by control circuitry 82 may, at least in part, be determined by measured voltage levels taken across battery power supply 70 and supplied to control circuitry 82 by way of line 106. (Voltage levels taken across power supply 70 may be measured in any conventional manner.) C In a first preferred embodiment of the present invention, when power source 16 is connected to electronic device 10 by way of connecting elements 34 and 40, power source 16 generates a signal of a low power level on line 22 during times in which electronic circuitry 52 is operative. And, power source 16 generates a signal on 0 line 22 of a high power level when electronic circuitry 52 is not, or is not to be, operative. When electronic circuitry 52 is not, or is not to be, operative, the signal generated on line 22 by power source 16 is of a sufficiently high power level to recharge the battery cells of battery power supply 70. 5 In another preferred embodiment, power source 16 is operative in a similar manner, but the signal generated on line 22 is further dependent upon the amount of charge stored in battery power supply 70. (And the amount of charge stored in power supply 70 is proportional to the voltage levels taken thereacross.) That is to say, 0 when the value of the signal generated by control circuitry 82 on line 100 is of a value dependent, at least in part, upon the value of the signal applied to control circuitry 82 on line 106, variable-level power source 16 generates a signal on line 22 at a level between the aforementioned two power levels wherein the particular power level

of the signal is dependent upon the amount of charge already stored in the battery cells of battery power supply 70.

In either embodiment, however, the power level of the signal generated by variable-level power source 16 on line 22 is selected to be of a value to minimize excessive heat generation during operation of electronic device or recharging of the battery cells of battery power supply 70.

Turning next to the block diagram of FIG. 2, a radio transceiver, here a radiotelephone, referred to generally by reference numeral 210, of a preferred embodiment of the present invention is shown. Radiotelephone 210 corresponds to electronic device 10 of FIG. 1. Variable-level power source 216 is releasably connectable to radiotelephone 210 by way of lines 222 and 228 which are connected to connecting elements 234 and 240, here shown to be plug connectors, represented by plug terminals positioned within the rectangles shown in dash. Variable-level power source 216 may, in turn, be connected to a conventional, household power supply (by way of connection with plug connector 236) or the power supply of a motor vehicle. Power source 216 is operative to generate a charging signal on line 222 of a selected power level.

Line 246 of radiotelephone 210 interconnects connecting element 234 and transceiver circuitry of radiotelephone 210, here shown to be comprised of receiver circuitry portion 250 and transmitter circuitry portion 252. When power source 216 is connected to connecting element 234 of radiotelephone 210, the signal generated by power source 216 is permitted to be applied to receiver and transmitter circuitry portions 250 and 252 to provide circuitry portions 250 and 252 with operative power to operate the respective circuitry portions. Charge regulator 258 also forms a portion of radiotelephone 210 and is coupled to line 246 to receive the signal generated by power source 216 when power source 216 is connected to connecting element 234 by way of line 222. Charge regulator 258 is operative to regulate the value of the signal applied thereto on line 246 and to generate a regulated, charging signal on line 264 which is applied to

rechargeable battery power supply 270 to permit recharging of the battery cells thereof.

Rechargeable battery power supply is coupled to receiver and transmitter circuitry portions 250 and 252 by way of line 276. When variable-level power source 216 is not connected to radiotelephone 210, energy stored within the battery cells of rechargeable battery power supply 270 is utilized to provide the operative power to operate receiver and transmitter circuitry portions 250 and 252.

Control circuitry 282 is coupled to the receiver and transmitter circuitry portions 250 and 252 by way of line 288, to charge regulator 258 by way of line 294, to connecting element 240 by way of line 300, and to rechargeable battery power supply 270 by way of line 306.

Signals provided to control circuitry 282 on line 288 are indicative of times in which circuitry portions 250 and 252 are operative. (As mentioned previously, during operation of radiotelephone 210, receiver circuitry portion 250 is oftentimes powered in the "standby" mode while the transmitter circuitry portion of the radiotelephone is typically operative only during times in which two-way communication is to be effectuated by the radiotelephone.)

When only receiver circuitry portion 250 or neither receiver nor transmitter circuitry portions 250 or 252 are operable, control circuitry 282 generates a signal on line 300 for application to variable- level power source 216 by way of connecting element 240 and line 228 of a first signal level. Conversely, when signals applied to control circuitry 282 on line 288 indicate that transmitter circuitry portion 252 is, or is to be, operable, control circuitry 282 generates the signal on line 300 to be of a second signal level. Responsive thereto, power source 216 generates a signal on line 222 of a power level dependent upon the signal level of the signal generated on line 300 by control circuitry 282.

In a preferred embodiment of operation of radiotelephone 210, when transmitter circuitry portion 252 is not, or is not to be, operable, the signal of the first signal level generated on line 300 by control circuitry 282 causes power source 216 to generate a signal on line 222

of a power level to permit recharging of the battery cells of battery power supply 270.

When transmitter circuitry portion 252 is operative, control circuitry 282 generates the signal on line 300 of the second signal 5 level value to cause power source 216 to generate a signal on line 222 which is of a second power level which permits operation of the transmitter circuitry portion 252 (and also receiver circuitry portion 250) but not to recharge the battery cells of rechargeable battery power supply 270. In such manner, recharging of the battery cells of 10 rechargeable battery power supply 270 occurs only when transmitter circuitry portion 252 is not operative. Thereby, overheating of radiotelephone 210 responsive to simultaneous recharging and transmission is avoided.

The control signal generated by control circuitry 282 on line 294 '15 is operative to control operation of charge regulator 258. When the signal generated by power source 216 is to be utilized to apply a charging current to recharge the battery cells of battery power supply 270, the charge control signal generated by control circuitry 282 on line 294 is of a level to cause the regulated charging signal generated 20 on line 264 to be of a value to effectuate such recharging. The precise value of the regulated charging signal is maintained by way of a feedback control loop.

When, conversely, the battery cells of battery power supply 270 are not to be recharged (e.g., during times in which transmitter 25 circuitry portion 252 is to be operable), the charging control signal generated by control circuitry 282 on line 294 is of a level to cause no regulated charging signal to be generated by charge regulator 258 on line 264.

Accordingly, in the preferred embodiment, when transmitter 30 circuitry portion 252 of radiotelephone 210 is to be operative to transmit modulated signals, control circuitry 282 generates a signal on line 294 to prevent application of a regulated charging signal to the battery cells of the battery power supply 270 and also to generate a signal of the first signal level on line 300 to cause power source 216 to

generate a signal on line 222 of a reduced level required to power only receiver and transmitter circuitry portions 250 and 252.

Conversely, when transmitter circuitry portion 252 is not to be operative, the charge control signal generated on line 294 is of a level to permit a regulated charging signal to be applied to the battery cells of battery power supply 270, and the signal of the second signal level is generated on line 300 to cause power source 216 to generate a signal on line 222 of a power level to permit recharging of the battery cells of battery power supply 270. (Circuitry internal to receiver and transmitter circuitry portions 250 and 252 prevent application of power on line 246 to power the respective circuitry portions 250 and 252.)

Radiotelephone 210 is further shown to include input element 312 which is coupled to receiver and transmitter circuitry portions 250 and 252 by way of line 318. Similarly, display element 324 is also coupled to portions 250 and 252, here by way of line 328.

Turning next to the partial block, partial schematic diagram of FIG. 3, a charge regulator, here designated by reference numeral 358, is shown. Charge regulator 358 is analogous to charge regulator 258 of radiotelephone 210 of FIG. 2 and to charge regulator 58 of electronic device 10 of FIG. 1. A charging signal similar to the signal generated by power sources 216 and 16 of the preceding figures, is applied to charge regulator 358 on line 446. A charge control signal is applied to charge regulator 358 on line 494 in a manner analogous to the manner in which the charge control signal is generated on lines 94 and 294 of charge regulators 58 and 258 of FIGs. 1 and 2, respectively. And, a regulated charging signal is generated on line 464 in a manner analogous to the manners in which regulated charging signals are generated on lines 64 and 264 of FIGs. 1 and 2, respectively.

The signal generated on line 446 is applied to a source electrode of field effect transistor 504. The drain electrode of transistor 504 is coupled to line 464 across resistor 510 and diode 516.

Comparator 524, configured to form a differential amplifier, includes a positive input coupled to the left-hand side of resistor 510

by way of resistor 530. A negative input of comparator 524 is coupled to a right-hand side of resistor 510 by way of resistor 536. Shunt resistors 542 and 548 are further coupled to the positive and negative inputs, respectively, of comparator 524. 5 Comparator 524 generates a differential output signal on line

554 representative of differences between the signal applied at the positive and negative inputs thereof. As the signals applied to the positive and negative inputs of comparator 524 are indicative of the voltage levels at the left- and right-hand side portions of resistor 510,

10 the signal generated on line 554 is representative of the voltage drop across resistor 510 (and, as voltage is related to the current at the drain electrode, the signal generated on line 554 is related to the current at line 464).

Line 554 is coupled to a positive input of comparator 560.

7.5 Comparator 560 is also configured to form a differential amplifier. A charge control signal generated on line 494 is applied to a negative input of comparator 560. The differential output of amplifier 560 generated on line 566 is applied to a gate electrode of transistor 504 by way of resistor 572. Shunt capacitor 578 is further connected between

20 the gate electrode of transistor 504 and ground. The loop formed between the drain electrode of transistor 504 and the gate electrode thereof forms a feedback loop which permits control of the current (and, hence, the power level) of the signal generated on line 464 as the value of the signal applied to the gate electrode of transistor 504

25 causes transistor 504 to operate in a conventional manner (analogous to operation of a valve) to control the current level of the drain electrode and line 464. And, the value of the charge control signal applied on line 494 controls the value of the signal applied to the gate electrode. Appropriate variation of the value of the signal generated

30 on line 494 results in a signal generated on line 464 to be of any desired value.

Turning next to the schematic view of FIG. 4, a radiotelephone, referred to generally by reference numeral 610 is shown. Radiotelephone 610 corresponds to radiotelephone 210 shown

35 in the block diagram of FIG. 2. Elements of radiotelephone 210

shown in block form in FIG. 2 are disposed within the housing of radiotelephone 610 of FIG. 4 but for rechargeable battery power supply 270 which here is shown to comprise battery pack 614..

Radiotelephone 610 is connected to variable- level power source 616 by way of lines 622 and 628 which connect power source 616 to connecting elements of radiotelephone 610 through plug connector 630. (Connecting elements of radiotelephone 610 are hidden from view in the figure, but correspond to connecting elements 234 and 240 of FIG. 2.) Plug connector 636 is also shown in the figure permitting connection of power source 616 to a conventional household power supply. (While plug connector 636 comprises a plug connector permitting connection to a conventional household power supply, other plug connectors permitting connection to other types of power supplies are, of course, similarly possible.) Because power source 616 is positioned remote from radiotelephone 610, but connected thereto by way of lines 622 and 628, radiotelephone 610 may be conveniently operated by a user in spite of the connection between radiotelephone 610 and power source 616. When radiotelephone 610 is operative to be in the "standby" mode, a control signal generated by radiotelephone 610 on line 628 causes power source 616 to generate a signal of a relatively high power level on line 622 to permit recharging of the battery cells of battery pack 614 comprising a rechargeable power supply. When, however, radiotelephone 610 is operative to transmit modulated signals, radiotelephone 610 generates a control signal on line 628 to cause power source 616 to generate a signal on line 622 of a relatively low power level; the battery cells of battery pack 614 are not recharged and the signal generated on line 622 is of a power level to permit powering of the transmitter and receiver circuitry portions of the radiotelephone. In such manner, overheating of radiotelephone 610 is prevented as the transmitter circuitry portions of radiotelephone 610 and recharging of the battery cells of battery pack 614 do not occur simultaneously.

Turning next to the flow diagram of FIG. 5, an algorithm, referred to generally by reference numeral 700 which is executable by

control circuitry of radiotelephone 210 of FIG. 2 is shown. When executed, algorithm 700 causes control circuitry 282 to generate control signals on lines 294 and 300 to control application of charging currents to rechargeable battery power supply 270 (or, with respect to radiotelephone 610 of FIG. 4, battery pack 614) and also the power level of the signal generated by power source 216 (or, with respect to radiotelephone 610, power source 616).

First, and as indicated by decision block 706, a determination is made as to whether the variable-level power source is connected to the radiotelephone. If the power source is not connected to the radiotelephone, the no branch is taken, and the receiver and transmitter circuitry portions 250 and 252 of radiotelephone 210 are powered with the stored energy of battery power supply 270. If, however, the power source is connected to the radiotelephone, the yes branch is taken to decision block 718 and a determination is made as to whether transmitter circuitry portion 252 is operable to transmit modulated signals. If the radiotelephone is in the "standby" mode or transmitter circuitry portion 252 is otherwise not to be operable, the no branch is taken, a control signal of the first signal level is generated on line 300, as indicated by block 724, and the charge control signal generated on line 294 is generated to be of a value, and as indicated by block 730, to-permit charge regulator 258 to generate a regulated charging signal on line 264 to recharge the battery cells of battery power supply 270. If, however, transmitter circuitry portion 252 is to be operable, the yes branch is taken from decision block 718, the control signal generated on line 300 is of a second signal level value, as indicated by block 736, and the charge control signal generated on line 294 is of a signal level, as indicated by block 742 to cause charge regulator 258 not to generate a regulated charging signal on line 264. Algorithm 700 is repeated during operation of radiotelephone 210.

FIG. 6 is a logical flow diagram listing the method steps of the method, referred to generally by reference numeral 800, of a preferred embodiment of the present invention. Method 800 permits powering of transceiver circuitry of a radiotelephone which is

operable to receive operative power of either of at least two power levels generated by a variable-level power source when the variable- level power source is connected to the radiotelephone.

First, and as indicated by block 806, the variable-level power source is releasably connected to the radiotelephone to provide operative power to the radiotelephone.

Next, and as indicated by block 812, a rechargeable power supply is coupled to receive a charging signal responsive to times in which the variable-level power source is coupled to provide operative power of a first power level to the electronic device.

Next, and as indicated by block 818, the transceiver circuitry is provided with either the operative power generated by the variable- level power source or power generated by energy stored by the rechargeable power supply. Finally, and as indicated by block 824, a power-source control signal is generated for application to the variable-level power source wherein the power source control signal is of either of at least a first signal level to cause the operative power of the variable-level power source to be a first of the at least two power levels or of a second signal level to cause the operative power of the variable-level power source to be of a second of the at least two power levels.

Because the electronic device of the preferred embodiment of the present invention, and the method therefor, causes the power level of an externally-generated signal to be of a level dependent upon the power needs of such electronic device, generation of excessive amounts of heat caused as a result of applying large amounts of power to the electronic device is avoided.

While the present invention has been described in connection with the preferred embodiments shown in the various figures, it is to be understood that other similar embodiments may be used and modifications and additions may be made to the described embodiments for performing the same function of the present invention without deviating therefrom. Therefore, the present invention should not be limited to any single embodiment, but rather construed in breadth and scope in accordance with the recitation of the appended claims.