Rohm Co., Ltd.

Shigekane Matsui

Isao Yamamoto

Hiroyuki Ishikawa

Tetsuro Hashimoto

Kimio Ando

A power supply apparatus comprises a driver, an oscillator, a digital control circuit and a counter. The driver is connected to a power source voltage and performs an ON/OFF operation of supplying power to a load. The oscillator outputs an oscillator signal every constant period. The digital control circuit performs an ON/OFF control of the driver based on the oscillator signal outputted from the oscillator. The counter counts the oscillator signal outputted from the oscillator. The digital control circuit sets a threshold value representing an upper limit of a count value counted by the counter and stops an output operation of the oscillator signal by the oscillator when the count value counted by the counter exceeds the set threshold value.

Power supply apparatus, power supply system and power supply method with an on/off operation of supplying power

A power supply apparatus, comprising: a driver connected to a power source voltage and configured to perform an ON/OFF operation of power supply to a load; a digital control circuit configured to perform an ON/OFF control of the driver; and an oscillator configured to output an oscillator signal for performing the ON/OFF control of the driver every constant period. The digital control circuit operates in a normal control mode in which the output operation of the oscillator signal by the oscillator and the ON/OFF operation of the driver are continuously activated, or in a low power control mode in which the output operation of the oscillator signal by the oscillator and the ON/OFF operation of the driver are intermittently activated.

Power supply apparatus, power supply system and power supply method

A detection circuit is mounted on an electronic device having a communication function, including at least a battery, a CPU, and a communication unit, and is configured to detect the remaining battery charge. An A/D converter performs sampling of a magnitude of a current Idischarged from the battery, and converts the current Ithus sampled into a digital current value. An interface circuit receives, from the CPU, control data which indicates a period in which there is an increase in the current discharged from the battery. Based upon the control data, a control unit raises the sampling frequency of the A/D converter in the period in which there is an increase in the current I.

Battery fuel gauge circuit

A pulse generating unit receives a clock at a predetermined frequency, and generates a pulse signal which transits synchronously with the positive edge of the clock. A flip-flop acquires the pulse signal every time a positive edge occurs in an inverted clock output from the inverter. A logic gate multiplexes the pulse signal and the output of the flip-flop. A selector selects either the output of the logic gate or the pulse signal.

Pulse generating circuit and pulse width modulator

A battery is charged by using in series a constant-voltage DC power supply with current limit function and a constant voltage circuit which has a differential comparator circuit and whose current limit value is variable. Following a period of charging with the current of current limit value by the constant-voltage DC power supply, a period is provided in correspondence with the state of charging of the battery, for charging with a current limit value of the constant voltage circuit which is smaller than that current limit value. The detection of the charging state of the battery is effected by a comparison between a current value of a current source of a differential comparator circuit and a differential output of that differential comparator circuit. It enables to reduce electric power consumed by the control transistor of the constant voltage circuit and to reduce the allowable loss required for the control transistor.

Growing community of inventors

Kyoto, Japan

Shigekane Matsui