Fujitsu Corporation

Fujitsu Semiconductor Limited

Fijitsu Limited

Mitsuo Saeki

Hidekiyo Ozawa

Kouichi Matsuda

Hidetoshi Yano

Seiya Kitagawa

Toshiyuki Matsuyama

Shigeo Tanaka

Takashi Matsumoto

Kyuichi Takimoto

Yoshiaki Sano

Shigeaki Nakazawa

Nobuo Tanaka

Takahiro Shin

Yoshiro Takeda

Tsuyoshi Takimoto

Toshiaki Tsukuni

Akira Takeuchi

Koichi Matsuda

Masafumi Okumura

Nakazawa Shigeaki

A DC-DC converter includes: an inductor provided between a power input node and a power output node; a plurality of switching elements which switch an input route of a power toward the inductor and a discharge route of the power from the inductor; a first pulse generation circuit which generates a first pulse based on a feed-back signal according to an output of the output node; a second pulse generation circuit which generates a second pulse having a second frequency being equal to or higher than a first frequency set as an upper limit of a human audible frequency band; a driver which drives the switching element based on one of the first pulse and the second pulse; and a control circuit which supplies the first pulse or the second pulse to the driver based on a load state of a load coupled to the output node.

DC-DC converter, control circuit and information processing system

A battery unit includes: a battery having cell units connected in parallel, in which one or a plurality of battery cells is connected in series; an external terminal provided for the battery; a switching element provided between each internal terminal and the external terminal of the cell unit; a protection circuit monitoring whether or not a fault occurs in each of the plurality of cell units and cutting off, through the switching element, a connection between the internal terminal and the external terminal of the cell unit with the fault detected; and an informing signal output terminal notifying an external device that the connection with the external terminal with respect to at least one of the cell units is cut off.

Battery unit, battery system, electronic device, charging control method of battery, and discharging control method of battery

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

A DC-DC converter includes a switching element to generate a pulse waveform by repeatedly admitting and cutting off the input voltage, a fluctuation component restraining circuit to restrain a fluctuation component generated in superposition on the pulse waveform and having a shorter cycle than a cycle of the pulse waveform, and a control circuit to operate the fluctuation component restraining circuit when the input voltage is equal to or larger than a reference voltage.

DC-DC converter, method for controlling DC-DC converter, and electronic device

A power supply circuit includes: an input terminal; a DC voltage converter that converts a DC input voltage supplied to the input terminal into a DC output voltage; an output terminal that outputs the DC output voltage; a bypass circuit provided to the DC voltage converter between the input terminal and the output terminal; and a monitor control unit that monitors whether or not the DC input voltage satisfies a predetermined condition to be processed in the DC voltage converter, so as to connect the input terminal to the output terminal via the bypass circuit if the DC input voltage does not satisfy the predetermined condition.

DC/DC power supply circuit with a bypass circuit

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 permissible charging current and the maximum useable current.

To improve conversion efficiency at a DC-DC conversion time by providing driving units respectively for a plurality of switches and controlling the switches corresponding to a load current, an input voltage, an output voltage and an input/output voltage difference. When synchronously rectifying a plurality of first switches and a plurality of second switches by setting the first switches and the second switches alternately in an ON-state, the plurality of first switches are driven repeatedly in the ON- or OFF-state corresponding to a required output, the plurality of second switches are driven in the ON- or OFF-state in synchronization with the first switches, the driving of part of the plurality of first switches and part or all of the plurality of second switches is stopped corresponding to a load current value, an input voltage value, an output voltage value or an input/output voltage difference value.

Switching converter

In a DC-DC converter circuit having a plurality of input terminals connected to a plurality of DC power supplies, and an output terminal, the DC-DC converter circuit includes a power supply selection section for selecting a DC power supply of lowest voltage on the condition that the voltage is not less than a predetermined voltage, and a step-down type of regulator section for converting the voltage of the DC power supply selected by the power supply selection section into a predetermined voltage lower than the voltage of the DC power supply selected by the power supply selection section, and outputting the converted voltage through the output terminal.

DC-DC converter circuit, power supply selection circuit, and apparatus useful for increasing conversion efficiency

A direct-current to direct-current conversion (DC/DC) apparatus includes a control circuit having an error amplifier for voltage control, basing the conversion on a pulse width modulation control using an output of the error amplifier. The error amplifier inputs a voltage signal corresponding to an output voltage of a DC/DC result and a plurality of reference voltage signals. The DC/DC apparatus also includes a soft start capacitor to provide one of the plurality of reference voltage signals. The error amplifier amplifies a difference between the voltage signal corresponding of the output voltage of a DC/DC result and a voltage signal of a lower potential among the plurality of reference voltage signals and carries out the pulse width modulation control. Furthermore, the control circuit includes a circuit for discharging charges corresponding to the output voltage of the DC/DC result when a power supply to the control circuit is turned off.

DC to DC converter producing output voltage exhibit rise and fall characteristics independent of load thereon

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 &#x201c;1&#x201d;, so that the discharge control FET is OFF regardless of a discharge control signal supplied from a voltage monitor circuit. When a reset signal &#x201c;1&#x201d; is supplied to a reset terminal, the flip-flop outputs &#x201c;0&#x201d;. 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

A power supply control circuit connectable with an input power monitor that monitors an input power value to the power supply, an output power monitor that monitors an output power value from the power supply, and an output power controller that varies the output power value from the power supply, the power supply control circuit having an output power determiner that determines a determined output power value depending on the input power value and a power adjuster that adjusts the output power value to the determined output power value by controlling the output power controller.

Power supply control method

A direct-current to direct-current conversion (DC/DC) apparatus includes a control circuit having an error amplifier for voltage control, basing the conversion on a pulse width modulation control using an output of the error amplifier. The error amplifier inputs a voltage signal corresponding to an output voltage of a DC/DC result and a plurality of reference voltage signals. The DC/DC apparatus also includes a soft start capacitor to provide one of the plurality of reference voltage signals. The error amplifier amplifies a difference between the voltage signal corresponding to the output voltage of a DC/DC result and a voltage signal of a lower potential among the plurality of reference voltage signals and carries out the pulse width modulation control. Furthermore, the control circuit includes a circuit for discharging charges corresponding to the output voltage of the DC/DC result when a power supply to the control circuit is turned off.

DC to DC converter producing output voltage exhibiting rise and fall characteristics independent of load thereon

There are disclosed a synchronous rectifying type of DC&#x2014;DC converter, a DC&#x2014;DC converter control circuit constituting such a type of DC&#x2014;DC converter, a monitor circuit for monitoring an operation of a DC&#x2014;DC converter, and an electronic equipment having a DC&#x2014;DC converter, considering a conduction current. A DC&#x2014;DC converter has a main switch and a synchronous rectifying switch, in which said main switch and said synchronous rectifying switch are alternately turned on so that a voltage of a DC electric power is transformed and outputted. A state that said main switch and said synchronous rectifying switch are simultaneously turned on is detected.

Spike control apparatus for DC-DC converter

When starting charging of an internal battery as a result of connection of an external power source by an AC adapter, a charging control unit sets a first charging voltage at which the charging capacity of the internal battery is maximized. When starting the charging from recognition of reduced capacity of the internal battery due to its self-discharge in desk-top use where the AC adapter is in connection at all times, the charging control unit sets a second charging voltage lower than the first charging voltage to prevent the battery from degrading.

Growing community of inventors

Kawasaki, Japan

Mitsuo Saeki