Hewlett-packard Company

Hewlett-packard Corporation

Preston D Brown

Robert B Puckette

David A Williams

Masahiko Muranami

Charles S Stephens

Terry G Bradley

Dennis C York

Tuan Tran

Curtis Rose

Lester S Moore

A clock reference frequency is digitally derived from a base signal, then digitally modulated by ramping the clock reference frequency up and down about a desired frequency. The modulation occurs in periodic fashion at a prescribed modulation frequency. Such modulation spreads the electromagnetic energy of the system signals over a band that is a portion of the desired clock frequency. As a result, energy in harmonics of the respective system signals also are spread. When the energy spreading of any system signal or harmonic of such signal occurs over a bandwidth greater than the 120 kHz bandwidth of conventional communication receivers, adverse EMI emissions are reduced.

Digital method and apparatus for reducing EMI emissions in

A battery charger is connected to a power source via an input cable. The battery charger has charge switching circuitry for delivering a charge to a battery under the control of a controller. The controller has state detection logic for detecting the current state of the battery, and charging logic for charging the battery by selectively enabling and disabling the charge switching circuitry based on the condition of the battery. An output cable is connected to the battery charger. The output cable delivers power from the power source to a second battery charger for charging a second battery for the electronic device. The output cable can be placed in a stowage position or a non-stowage position. The second battery charger may be external or internal to the electronic device. If the second battery charger is internal to the electronic device, two batteries can be charged at the same time the electronic device is being operated. The battery charger has the additional capability of detecting and correctly charging different battery types, and responding to error conditions detected during the charging operation.

Portable battery charger with integrally attached output cable

A high efficiency power supply for producing two regulated output voltages (i.e. 3.3 and 5 volts) from an unregulated input voltage. The supply includes a 4-15 volt battery pack, a first (5.0 volt) output, a second (3.3 volt) output, and a ground. The positive terminal of the battery is connected directly to the second output. The 3.3 volt differential with ground is maintained by a voltage regulator that couples the negative terminal of the battery pack to ground (i.e. ground floats relative to the battery). A second voltage regulator couples the positive terminal of the battery pack to the first output, and maintains this first output at 5.0 volts relative to ground. This latter regulator is capable of boost operation, permitting a 5.0 volt output to be maintained even if the battery pack voltage is less than this value. Neither regulator includes a transformer, making the supply particularly well suited for use in miniaturized equipment, such as palmtop computers.

Dual voltage power supply

Optical transceiver (22) for calculator-to-calculator or calculator-to-module communication. The transceiver (22) includes an IR transmitter (24) and IR receiver (26) designed for use in the low power, low cost environment of calculators and portable computing devices. The transceiver may be adapted to communicate with the CPU (central processing unit (14) of a calculator (90) directly or with that of a portable computing device via its serial port (43). Devices in which the optical transceiver may be incorporated include calculators, plugless modules, and books containing plugless modules. Data such as mathematical formulas within the book may be stored in the associated module and transferred instantaneously and accurately to an adjacent calculator upon request by the calculator.

Low power optical transceiver for portable computing devices

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Eugene, OR, United States of America

Preston D Brown