Rohm Co., Ltd.

Koichi Inoue

Hiroyuki Fujita

Masahito Kondo

Satoshi Furuno

Hirokazu Oki

Koichi Yamasaki

Yuzo Ide

Takao Osuka

Hiroyuki Okada

Kenji Otani

Takahiro Ota

Nobuhiro Nishikawa

Yoshihisa Hiramatsu

Kenji Ohtani

Masanari Shougomori

Keisuke Naganuma

Takeshi Morishita

A voltage detection circuit of the invention is composed of the minimum needed number of circuit elements and that permits the temperature characteristic of the reference level for voltage detection to be set arbitrarily. The voltage detection circuit has a first transistor and a second transistor that have the emitters thereof connected together to form a differential pair, a voltage division circuit that divides the input voltage into a first division voltage and a second division voltage, that is connected directly to the base of the first transistor to apply the first division voltage thereto, and that is connected directly to the base of the second transistor to apply the second division voltage thereto, and a resistor that has one end thereof connected to the base of the second transistor and that has the other end thereof connected to the emitter of the second transistor. Whether the input voltage is equal to a predetermined level or not is checked based on the output from the differential pair.

Voltage detection circuit

A power supply apparatus has a regulator and a regulator protection circuit. On detecting an abnormality, an abnormality detection circuit in the regulator protection circuit turns the regulator off. Based on the output of the abnormality detection circuit, an abnormality detection incidence checking circuit in the regulator protection circuit checks whether or not an abnormality has been detected a predetermined number of times within a predetermined length of time. When the abnormality detection incidence checking circuit recognizes that an abnormality has been detected the predetermined number of times within the predetermined length of time, an abnormality detection level setting circuit in the regulator protection circuit decreases the detection level of the abnormality detection circuit. This helps reduce the incidence of malfunctioning of the load to which the regulator feeds its output due to repeated detection of an abnormality and recovery therefrom.

Regulator protection circuit and power supply apparatus incorporating it

In a conventional semiconductor integrated circuit device, a means for preventing a backflow current has a high on-state resistance, which makes it impossible to reduce the voltage loss in normal operation. A semiconductor integrated circuit device of the invention has a first MOS transistor, a second MOS transistor provided between the first MOS transistor and a power supply terminal, and a means that, in normal operation, keeps the gate of the second MOS transistor at a predetermined potential (preferably the ground potential) and that, when a backflow current is likely, turns the second MOS transistor off. This helps prevent a backflow current while reducing the voltage loss in normal operation.

Semiconductor integrated circuit device

A semiconductor integrated circuit device has a MOS transistor Mincluding a parasitic diode Dxfor preventing a reverse current due to a parasitic diode Dxof a MOS transistor M. The semiconductor integrated circuit device further has a voltage setting circuitfor turning the MOS transistor Moff in a reversely biased state, and an anti-reverse-current elementfor preventing a reverse current from flowing through the voltage setting circuitin a reversely biased state. In normal operation, a direct-current voltage within the withstand voltage range of the MOS transistor Mis fed to the gate thereof according to the voltage applied to the conductive terminalof the MOS transistor M

Semiconductor integrated circuit device configured to prevent the generation of a reverse current in a MOS transistor

An H-bridge driver has a drive signal generating circuit for generating a square-wave signal as a drive signal. The H-bridge driver also has a waveform shaping circuit for blunting the waveform of the drive signal at the rising and trailing edges thereof. The waveform shaping circuit has a first circuit for generating, in a rising period of the square-wave signal fed thereto, a first current having a positive peak at the center of the rising period, a second circuit for generating, in a trailing period of the square-wave signal fed thereto, a second current having a negative peak at the center of the trailing period, and a capacitor to which the first and second currents are fed. The waveform shaping circuit outputs the voltage across the capacitor as its output voltage.

H-bridge driver

A semiconductor device has a transistor that controls, according to the resistance of the load externally connected to the output terminal thereof, the current fed to the base of an output-stage transistor for driving the load to turn it on. In this circuit configuration, even if a base current of the output-stage transistor is so determined as to permit the semiconductor device to drive the heaviest permissible load, only a reduced amount of extra current is fed to the base of the output-stage transistor when it is turned on with a light load connected to the semiconductor device.

Low power consumption output driver circuit and supply voltage detection circuit

A power supply device produces a predetermined voltage from a supply voltage through a voltage follower composed of a plurality of transistors. The voltage follower has a function of preventing backflow current. The voltage follower has one end connected to the supply voltage and another end connected to a capacitor. A constant voltage generating circuit produces a constant voltage from the voltage across the capacitor. A switch circuit is connected between the supply voltage and the control electrode of one of the transistors constituting the voltage follower other than the first-stage transistor thereof. A voltage drop detecting circuit detects a drop below a predetermined level in the voltage across the capacitor, and turns on the switch circuit on detecting such a drop.

Power supply device

A stabilized DC power supply device that maintains an output voltage thereof at a constant level despite a fluctuation arising in a power supply voltage fed thereto comprises a control circuit that compares the output voltage with a reference voltage so as to output a control signal by which the output voltage is maintained at a predetermined level, and a ripple cancellation circuit that amplifies an undulating component included in the power supply voltage at a predetermined gain and that feeds out a resulting signal as an undulation compensation signal for correcting the output voltage, wherein the undulation compensation signal for correcting the output voltage is superimposed on the reference voltage so as to prevent an undulation arising in the power supply voltage from appearing in the output voltage.

Stabilized DC power supply device

A switching regulator, by turning a switching device on and off, converts the level of a direct-current voltage fed in via an input terminal, and then feeds out the thus level-converted voltage via an output terminal. A waveform shaping circuit blunts the waveform of the signal with which the switching device is turned on and off.

Switching regulator with reduced high-frequency noise

A hysteresis circuit has a comparator which compares a threshold voltage and an input voltage. The threshold voltage is supplied from a voltage dividing circuit having resistors. A constant current circuit is connected to a voltage divided point of the voltage dividing circuit through a switch. The ON and OFF of the switch is controlled by an output of the comparator. When the switch is turned ON, a constant current flows to the voltage divided point, so that the value of the threshold voltage supplied from the voltage dividing circuit to the comparator is changed.

Hysteresis circuit

A control device having a forced operation function has an output circuit that operates in response to an output control signal generated within the control device and a terminal for feeding a signal from the output circuit to outside the control device. The control device further has a signal detection circuit that outputs a forced operation signal when a predetermined signal is fed from the outside to that terminal. The output control signal generated within the control device and the forced operation signal produced by the signal detection circuit are fed through an OR circuit to the output circuit. This circuit configuration makes it possible to reduce the number of terminals to be provided in a control device having a forced operation function and thereby reduce its costs.

Control device with forced operation function and semiconductor integrated circuit device

A power supply monitoring integrated circuit device for individually detecting the voltages of a plurality of lithium-ion cells connected in series has a plurality of comparators for comparing the voltages obtained by dividing the voltages of the individual cells with a predetermined voltage. The power supply monitoring integrated circuit device also has terminals for feeding electric power from the individual cells through resistors to the inputs of the individual comparators and terminals for supplying electric power from the individual cells to the individual comparators, and, in accordance with the results of comparison by the individual comparators, controls charging or discharging of the cells.

Power supply monitoring integrated circuit device for individually monitoring voltages of cells

A power supply controlling integrated circuit device have detection input terminals for receiving the voltages of a plurality of cells and a plurality of comparing means for comparing the voltages of the individual cells with a predetermined reference voltage. To control discharging or charging of the cells in accordance with the outputs of the comparing means, a mode terminal is provided for receiving a signal for designating the number of cells. Also provided are a first circuit that can forcibly bring part of the comparing means into a predetermined output state in accordance with the signal received at the mode terminal and a second circuit for excluding from monitoring the outputs of those comparing means which have been brought into the predetermined output state. This enables the power supply monitoring integrated circuit device to control different numbers of cells without requiring any separately-mounted component or the like.

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Kyoto, Japan

Koichi Inoue