Denso Corporation

Anden Co., Ltd.

Ippei Kawamoto

Akira Sugiura

Fukuo Ishikawa

Takeyoshi Hisada

Satoshi Nakai

A temperature protection device includes temperature detection devices detecting the temperatures of switching elements and a control device controlling the switching elements. The control device stops driving of a first switching element the temperature of which rises to an overheat detection temperature and resumes the driving of the first switching element when the temperature of the first switching element drops to a return temperature. The control device controls timing of resuming the driving of the first switching element so that an undriven time period of the first switching element is longer in a case where at least one of the switching elements other than the first switching element is in a high load state when the temperature of the first switching element reaches the overheat detection temperature than that in a case where all the switching elements other than the first switching element are in a low load state.

Temperature protection device

A clock signal generator circuit includes a CR oscillator part, which outputs a clock signal having a frequency corresponding to a time constant determined by a capacitor and a resistor, and a frequency varying part. The frequency varying part includes a counter for performing a counting operation and varies a frequency of the clock signal by varying a resistance value of the resistor in correspondence to a count value of the counter. The resistor of the CR oscillator part includes plural resistive elements, one terminal of which are connected to a common node. The frequency varying part includes tri-state buffers, input terminals of which are connected in common and output terminals of which are connected to other terminals of the resistive elements, respectively, and varies the resistance value of the resistor by switching over states of the buffers in correspondence to the count value.

Clock signal generator circuit

A load driving device includes a switching element, a detector, a determination portion, a controller, and a threshold set portion. The switching element is arranged between a voltage source and a load, or between the load and a ground. The switching element is turned on to supply electric power from the voltage source to the load. The detector detects a current flowing in the switching element. The determination portion compares a detection value of the detector and a threshold value, and determines whether an overcurrent flows in the switching element. The controller controls the switching element based on a determination result of the determination portion. The threshold set portion sets the threshold value to a higher value as voltage of the voltage source is higher. As such, responsiveness of the load driving device is improved and the switching element is protected when a short-circuiting occurs.

Load driving device

A shunt resistor, at least a part of which has a resistive element with pre-set resistivity, is configured to bridge between two electrodes and detect a current value of a current flowing between the electrodes by detecting a voltage drop in the resistive element. The shunt resistor includes two connecting parts affixed to the electrodes via a conductive adhesive, respectively, and the connecting parts electrically connected to the affixed electrodes, a bridging part bridging between the connecting parts by being extended from one of the connecting parts to the other one of the connecting parts, and two bonding wires used to detect a voltage drop in the resistive element. The bonding wires are bonded to the bridging part.

Shunt resistor

A switching element driving circuit includes a charge pump circuit and a drive voltage generating circuit. The charge pump circuit generates a boosted voltage. The drive voltage generating circuit generates a drive voltage for driving a switching element from the boosted voltage. The drive voltage generating circuit applies a current to a control terminal of the switching element through a resistor at least in an initial stage and an end stage of an output period during which a signal instructing the switching element to be turned on is outputted, and alleviates a rising and a falling of the drive voltage. A switching frequency of the charge pump circuit is set from 2 MHz to 30 MHz. As a result, generation of radio noise can be restricted in both of the drive voltage generating circuit and the charge pump circuit.

Switching element driving circuit

An overcurrent protection circuit includes a load drive section driving a load, a wire coupled with the load and the load drive section, a current detection section detecting a load current value of an electric current that flows to the load, an addition and subtraction section determining an addition and subtraction value based on the load current value and transmitting an integration result of addition and subtraction, a comparison circuit comparing the integration result with a threshold value, and a control circuit controlling the load drive section based on the comparison result. The addition and subtraction section includes an addition value determination circuit that determines an addition value in the addition and subtraction value based on the load current value and a function expression or information indicating a relationship between the load current value and the addition value.

Overcurrent protection circuit

A signal generator includes: a current control element for controlling a current flowing through an electric load; and signal forming means for outputting a control signal to the current control element. The signal forming means generates the control signal in such a manner that the current flowing through the electric load has a rising edge and a down edge of a substantially sine waveform. The rising edge of the current is disposed at a timing when the current control element is switched on. The down edge of the current is disposed at a timing when the current control element is switched off.

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Kariya, Japan

Ippei Kawamoto