Rohm Co., Ltd.

Romm Co., Ltd.

Toru Takuma

Shuntaro Takahashi

Naoki Takahashi

Makoto Sada

Toru Takahashi

Koji Katsura

Hajime Okuda

Kei Nagao

Yasunori Muramatsu

Yoshinori Fukuda

Adrian Joita

Katsuaki Yamada

Kenji Muraoka

A semiconductor device includes a semiconductor layer, an insulation gate-type first transistor which is formed in the semiconductor layer, an insulation gate-type second transistor which is formed in the semiconductor layer, and a control wiring which is formed on the semiconductor layer such as to be electrically connected to the first transistor and the second transistor, and transmits control signals that control the first transistor and the second transistor to be in ON states in a normal operation and that control the first transistor to be in an OFF state and the second transistor to be in an ON state in an active clamp operation.

Semiconductor device including insulation gate-type transistors

A semiconductor device includes: a first output transistor and a second output transistor configured to be connected between a first terminal and second terminal; an active clamp circuit configured to be connected to a first control terminal of the first output transistor to limit a terminal-to-terminal voltage appearing between the first and second terminals to a clamp voltage or less; a first variable resistive element provided between a node configured to be fed with a control signal and the first control terminal; a second variable resistive element provided between the node and a second control terminal of the second output transistor; and a turn-off circuit configured to be connected to a connection node between the second variable resistive element and the second control terminal so as to be able to turn the second output transistor off.

Semiconductor device, electronic appliance, and vehicle

A semiconductor device includes: a split-gate transistor connected between a drain electrode (output electrode OUT) and a ground electrode and having a plurality of individually controllable channel regions; an active clamp circuit configured to limit the output voltage VOUT appearing at the output electrode to a clamp voltage or below; and a gate control circuit configured to raise the ON resistance of the split-gate transistor gently (or stepwise) after the split-gate transistor is switched from the ON state to the OFF state before the active clamp circuit limits the output voltage VOUT.

Semiconductor device

An example switch device includes a switching element to connect/disconnect a current path from a power supply terminal to a ground terminal via a load, and an overcurrent protection circuit to limit output current flowing in the switching element to be an overcurrent limit value or less. When an output short circuit of the load is detected, the overcurrent protection circuit decreases the overcurrent limit value to be lower as a power supply voltage is higher. The overcurrent protection circuit includes a reference current generation portion that includes: a differential amplifier portion, an upper side current generation portion arranged to generate a predetermined an upper side current, a lower side current generation portion arranged to generate a lower side current, and a difference current generation portion arranged to output a difference current based on the lower side current and the upper side current, as the reference current.

Switch device

Disclosed is a gate control circuit that generates a gate control signal of an output transistor connected between an application end of a power supply voltage and an application end of an output voltage. The gate control circuit includes a first current source connected between the application end of the power supply voltage and the application end of the output voltage, a second current source connected between an application end of a booster voltage and an application end of a reference voltage, the booster voltage being raised to a voltage value higher than the power supply voltage in a steady state, an output stage that uses at least one of the first and second current sources to generate a gate charge current for charging a gate of the output transistor, and a controller that uses at least one of the first and second current sources according to the output voltage.

Gate control circuit, semiconductor device, electronic apparatus, and vehicle

In order both to accommodate instantaneous current as well as overcurrent protection in accordance with the load, an overcurrent protection circuit has: a threshold value generation unit that, in accordance with a threshold value control signal, switches between setting an overcurrent detection threshold value to a first set value (∝ Iref) and a second set value (∝ Iset) lower than the first set value; an overcurrent detection unit that compares a sense signal in accordance with the current being monitored and the overcurrent detection value and generates an overcurrent protection signal; a reference value generation unit that generates a reference value (∝ Iset) in accordance with the seconds set value; a comparison unit that compares the sense signal and the reference value, and generates a comparison signal; and a threshold value control unit that monitors the comparison signal, and generates a threshold value control signal.

Overcurrent protection circuit

An overcurrent protection circuit includes a hiccup controller which is configured to hiccup-drive a switching element such that an on-period and an off-period alternate. The hiccup controller controls at least one of the on- and off-period according to a temperature sense signal. The temperature sense signal can be generated by detecting at least one of temperature of the switching element and a difference in temperature between the switching element and another element. When at least one of temperature of the switching element and the difference in temperature between the switching element and the other element is higher than a predetermined threshold value, the hiccup controller can reduce the on-period ton and increase the off-period.

Disclosed herein is an overcurrent protection circuit configured to, upon detection of an output current that flows through a switch element reaching a first overcurrent limit value, reduce an overcurrent limit value for the output current from the first overcurrent limit value to a second overcurrent limit value smaller than the first overcurrent limit value.

Provided is an overcurrent protection circuit including an overcurrent detection unit configured to compare an output current flowing through a switch element and a predetermined overcurrent detection value to generate an overcurrent detection signal, an output activation detection unit configured to compare an output voltage and a predetermined threshold voltage to generate an output activation detection signal, a logic unit configured to combine the overcurrent detection signal and the output activation detection signal to generate a logic operation signal, and a diagnostic output unit configured to provide diagnostic output, the logic unit shifting the logic operation signal to a logic level of abnormal state when the overcurrent detection signal is shifted to a logic level of overcurrent detection state and holding the logic operation signal at that logic level, unless the output activation detection signal is shifted to a logic level of output activation state.

Overcurrent protection circuit, switch device, electronic apparatus, and vehicle

A switch device includes a switching element that connects/disconnects a current path from a power supply terminal to a ground terminal via a load, and an overcurrent protection circuit that limits output current flowing in the switching element to be an overcurrent limit value or less. When an output short circuit of the load is detected, the overcurrent protection circuit decreases the overcurrent limit value to be lower as a power supply voltage is higher. In addition, the switch device preferably includes a switching element that connects/disconnects a current path from a power supply terminal to a ground terminal via a load, an intermittent control unit that intermittently drives the switching element when an abnormality is detected, and an output voltage monitoring portion that disables the intermittent control unit until an output voltage applied to the load reaches its target value.

An overcurrent protection circuit includes a current control part configured to control conductance of a transistor so as to limit an output current flowing when the transistor is turned on to a predetermined upper limit or less, and a duty control part configured to forcibly turning on/off the transistor at a predetermined duty ratio when a temperature protection circuit detects a temperature abnormality in a state where the current control part limits the output current.

In order both to accommodate instantaneous current as well as overcurrent protection in accordance with the load, an overcurrent protection circuit has: a threshold value generation unit that, in accordance with a threshold value control signal, switches between setting an overcurrent detection threshold value to a first set value (&#x221d; Iref) and a second set value (&#x221d; Iset) lower than the first set value; an overcurrent detection unit that compares a sense signal in accordance with the current being monitored and the overcurrent detection value and generates an overcurrent protection signal; a reference value generation unit that generates a reference value (&#x221d; Iset) in accordance with the seconds set value; a comparison unit that compares the sense signal and the reference value, and generates a comparison signal; and a threshold value control unit that monitors the comparison signal, and generates a threshold value control signal.

Disclosed herein is a switch device including a switch element coupled between a power supply terminal and an output terminal, and an output abnormality detection circuit that. When an output current flowing during a turn-on period of the switch element is smaller than a threshold value, the output abnormality detection circuit detects an occurrence of an output abnormal condition, and increases a turn-on resistance of the switch element to determine which of a load-open condition and a short-to-power-supply-voltage condition is occurring at the output terminal on a basis of an output voltage at the output terminal.

Growing community of inventors

Kyoto, Japan

Toru Takuma