Cryptosystem designers frequently assume that secrets will be manipulated in closed, reliable computing environments. Unfortunately, actual computers and microchips leak information about the operations they process. This paper examines specific methods for analyzing power consumption measurements to find secret keys from tamper resistant devices. We also discuss approaches for building cryptosystems that can operate securely in existing hardware that leaks information.

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Differential Power Analysis

A battery pack includes a plurality of electrochemical cells and a control circuit. The battery pack provides power to a tool in the form of a pulse width modulated waveform. The plurality of electrochemical cells provide a total output voltage. The control circuit is coupled to the plurality of electrochemical cells and receives a trigger signal from the tool. In response to the trigger signal, the control circuit determines whether a pulse width of the pulse width modulated waveform requires adjustment. Additionally, the control circuit can be configured to receive an indication of the total output voltage. In this case, the control circuit determines whether the pulse width of the pulse width modulated wavefrom requires adjustment based on the level of the total output voltage.

Battery pack including input and output waveform modification capability

An electric power tool comprises a main body supporting a tool and an electric motor housed in the main body for driving the tool. A plurality of first battery interfaces is configured to removably receive or attach a plurality of first battery packs and to electrically connect the plurality of attached first battery packs in series with the electric motor. A plurality of indicators is configured to communicate information concerning the respective conditions of the plurality of attached first battery packs. The plurality of indicators is arranged such that all of the indicators are simultaneously viewable by a user of the electric power tool.

Electric tool powered by a plurality of battery packs and adapter therefor

A control system and method for simultaneously regulating the operation of a plurality of different types of switching power converters. The system utilizes in regulating the power converters sampled data and nonlinear feedback control loops.

Power converter circuitry and method

A DC converter and a mode-switching method used in an electronic apparatus are included. The electronic apparatus includes a subsystem circuit. The DC power converter comprises a first voltage converting circuit electrically connected to the subsystem circuit, receiving a system voltage and a first reference voltage, and converting the system voltage to a first output voltage based on the first reference voltage; and a second voltage converting circuit electrically connected to the subsystem circuit and receiving the system voltage and a second reference voltage, and converting the system voltage to a second output voltage to the same output end of the first voltage converting circuit based on the second reference voltage; wherein the second voltage converting circuit outputs the second output voltage to the subsystem circuit when the first output voltage at the output end is smaller than a threshold.

DC power converter and mode-switching method

A control system for charging enabling efficient charging of rechargeable batteries in an electronic apparatus which charges its rechargeable batteries by using a charger circuit when driving the apparatus by using an external power source, including first detecting unit for detecting a differential value between a maximum permissible charging current allowed by the rechargeable batteries and a charging current flowing to the rechargeable batteries; second detecting unit for detecting a maximum usable current by detecting a differential value between a maximum supplyable current allowed by the external power source and the current consumption of the apparatus; third detecting unit for detecting a differential value between a maximum useable current and the charging current flowing to the rechargeable batteries; and control unit for controlling the system in accordance with the differential values detected by the first and third detecting units so that the charger circuit generates the maximum charging current within the range where the charging current flowing to the rechargeable batteries does not exceed either of the maximum permissible charging current and the maximum useable current.

Control system for charging batteries and electronic apparatus using same

To avoid burning out a capacitor in a synchronous rectification type DC-to-DC converter due to overvoltages, the synchronous rectification type DC-to-DC converter includes a storage unit storing therein power derived from a power supply, switching elements connecting and disconnecting respective signal paths from power and ground, and a control unit controlling the connecting/disconnecting operations of the switching elements to maintain a voltage output from the storage unit at a predetermined value. The DC/DC converter also includes an overvoltage detecting unit monitoring a voltage derived from the power supply to thereby output an alarm signal when the voltage derived from the power supply exceeds a preselected voltage value, a shortcircuiting unit influencing the connecting conditions of the switching elements when the alarm signal from the overvoltage detecting unit is input therein, whereby the voltage derived from the power supply is shortcircuited, and an interrupting unit interrupting one of the signal paths by the power shortcircuited by the shortcircuiting unit.

DC-to-DC converter capable of preventing overvoltage

A protection method for preventing battery cells from over-discharging and being overcharged, a control circuit, and a battery unit are provided. In the protection method, when a set signal “1” is supplied to a set terminal, a flip-flop outputs “1”. The gate of a discharge control FET then becomes “1”, so that the discharge control FET is OFF regardless of a discharge control signal supplied from a voltage monitor circuit. When a reset signal “1” is supplied to a reset terminal, the flip-flop outputs “0”. The discharge control FET is then switched on and off in accordance with the output of a discharge control circuit of the voltage monitor circuit. In this manner, battery cells connected to an electronic device do not over-discharge, even when they are left unused for a long period of time. Thus, the battery unit can be prevented from deteriorating and shortening the life thereof.

Protection method, control circuit, and battery unit

In a power supply apparatus including a plurality of batteries and a plurality of power supply portions for connecting to loads, a plurality of switches connect these batteries to these power supply portions, respectively. The apparatus further includes a control mechanism which controls the opening and closing operations of the switches. When one of the switches is turned on in one of the power supply means, the control mechanism executes the control in such a manner that the other switches are turned off. The control mechanism further controls each of the switches on the basis of the remaining capacity of each battery and the load state of each power supply portion. Accordingly, the power supply operation can be flexibly carried out.

Power supply apparatus for supplying power from a plurality of batteries to a plurality of loads, and electronic appliance using the power supply apparatus

A protection circuit is used for a battery unit which has a plurality of cell parts coupled in parallel, and first and second power supplying terminals, where each of the cell parts includes a plurality of battery cells coupled in series, and first and second terminals respectively coupled to the first and second power supplying terminals. The protection circuit includes a plurality of switching elements making an electrical connection to the first terminal of a corresponding one of the cell parts and the first power supplying terminal, and disconnecting the electrical connection in response to an active signal, and a voltage monitoring circuit outputting the active signal to the switching elements when a voltage of at least one battery cell within one cell part falls outside a predetermined range, independently with respect to each of the cell parts.

Hidekiyo Ozawa

Papers

Control system for charging batteries and electronic apparatus using same

DC-to-DC converter capable of preventing overvoltage

Protection method, control circuit, and battery unit

Power supply apparatus for supplying power from a plurality of batteries to a plurality of loads, and electronic appliance using the power supply apparatus

Protection circuit and battery unit