Ricoh Company, Ltd.

Koichi Morino

Takaaki Negoro

Shinichi Kubota

Masatoshi Ito

Yuki Kashima

Shimpei Sakai

Kouichi Ikeda

A voltage clamp circuit includes a power supply, a first element connected with the power supply to output a constant current, a third element configured to allow a current to pass through when a voltage of a predetermined value or more is applied; and a second element configured to output a voltage according to a voltage generated by the first and third elements.

Voltage clamp circuit and integrated circuit incorporating same

A testing method for testing a semiconductor device includes heating the semiconductor device until the temperature of the semiconductor device reaches a predetermined temperature; conducting other functional tests other than testing of the overheat protection function in a second step after the temperature of the semiconductor device has reached the predetermined temperature; allowing the semiconductor device to generate heat by itself such that the overheat protection function of the semiconductor device is activated, detecting a first diode forward voltage of a desired diode contained in the semiconductor device when the overheat protection function of the semiconductor device is activated and computing a first computational temperature of the semiconductor device based on the detected first diode forward voltage of the desired diode contained in the semiconductor device; and determining whether the computed first computational temperature of the semiconductor device resides in the overheat protection function activating temperature range.

Device and method for testing semiconductor device

A voltage regulator includes a driver transistor, a feedback voltage generator, a reference voltage generator, a first differential amplifier, and a differential gain controller. The driver transistor is connected between input and output terminals to conduct a current therethrough according to a control signal applied to a gate terminal thereof. The feedback voltage generator is connected to the output terminal to generate a feedback voltage. The reference voltage generator generates a reference voltage. The first differential amplifier has an output thereof connected to the gate terminal of the driver transistor, and a pair of differential inputs thereof connected to the feedback voltage generator and the reference voltage generator, respectively, to generate the control signal at the output thereof. The differential gain controller is connected to the output of the first differential amplifier to control the differential gain according to a difference between the input and output voltages.

Constant voltage regulator

A voltage detector includes a first input terminal, a second input terminal, a first voltage detection circuit, a second voltage detection circuit, and a logic holder circuit. The first input terminal receives a first input voltage. The second input terminal receives a second input voltage. The first voltage detection circuit outputs a first detection signal that switches a logic state thereof when the first input voltage falls below a first detection voltage. The second voltage detection circuit outputs a second detection signal that switches a logic state thereof when the second input voltage falls below a second detection voltage. The logic holder circuit retains the logic state of the first detection signal when the second detection signal indicates that the second input voltage is below the second detection voltage.

Voltage detector

A semiconductor circuit includes a voltage regulator and a buffer transistor. The voltage regulator converts an input voltage input to an input terminal thereof into an output voltage output to an output terminal thereof. The buffer transistor is an n-channel depletion-mode metal-oxide semiconductor field effect transistor, disposed between the power supply terminal and the voltage regulator with a gate terminal thereof connected to the power supply terminal, a drain terminal thereof connected to the power supply terminal, and a source terminal thereof connected to the input terminal of the voltage regulator.

Semiconductor circuit and constant voltage regulator employing same

A constant voltage circuit configured to convert an input voltage into an output voltage having a predetermined level is disclosed. The constant voltage circuit includes a differential amplifier circuit configured to produce an output signal having a voltage level in response to a reference voltage and the output voltage; and an output circuit configured to receive the output signal and produce a current in response to the voltage level of the output signal. The output voltage is proportional to the current. The output circuit includes plural output transistors and a transistor selecting unit configured to select one or more output transistors to be operated among the plural output transistors to produce the current depending on the level of the output voltage.

Constant voltage circuit including supply unit having plural current sources

A disclosed overcurrent protection and output short-circuit protection circuit has a proportional output current generation unit and a first current voltage conversion unit provided in series between a first power supply terminal and an output terminal. Furthermore, the overcurrent protection and output short-circuit protection circuit has a control unit that operates based on a difference between a voltage generated at the first current voltage conversion unit and that generated at a second current voltage conversion unit provided between the first power supply terminal and a second power supply terminal. A current flowing to the second current voltage conversion unit is changed by one or more switching elements in a stepwise manner based on the output voltages of the output transistor when supplying the current, thereby changing the voltages generated at both ends of the second current voltage conversion unit.

Overcurrent limitation and output short-circuit protection circuit, voltage regulator using overcurrent limitation and output short-circuit protection circuit, and electronic equipment

A semiconductor device and an electronic apparatus incorporating the semiconductor device are disclosed. The semiconductor device includes a power circuit that further includes a power transistor for providing current to a load (load current), a temperature detector for detecting the temperature of the power transistor, and a current detector for detecting the load current. If the detected temperature of the power transistor reaches a first predetermined temperature, and if the detected load current exceeds a first predetermined load current, a signal is output through an external terminal of the semiconductor device.

Semiconductor device and an electronic apparatus incorporating the semiconductor device

A voltage detecting circuit for comparing a voltage to be detected with a reference voltage and outputting an output signal having a level depending on the comparison is disclosed. The voltage detecting circuit includes an inverting amplifier circuit configured to receive an intermediate signal having a level depending on the comparison and output the output signal. The inverting amplifier circuit includes an active element having a control terminal. A threshold voltage of the control terminal is as low as or lower than the reference voltage. The voltage to be detected is applied to the control terminal of the active element.

Voltage detecting circuit

A voltage regulator having a MOS transistor driver includes a p-channel MOS transistor at a voltage input terminal Vin and a p-channel MOS transistor at a voltage output terminal Vout. A drain of the input side p-channel MOS transistor is connected to the voltage input terminal Vin. A threshold voltage or a voltage lower than the threshold voltage is applied to a gate of the input side p-channel MOS transistor. A drain of the output side p-channel MOS transistor is connected to the voltage output terminal Vout. A current flowing through the input side p-channel MOS transistor drives a voltage regulator circuit and the output side p-channel MOS transistor.

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Kanagawa, Japan

Koichi Morino