Denso Corporation

Akio Kojima

Junichi Nagata

Masahiro Kitagawa

Mitsuhiro Saitou

Nobutomo Takagi

Kiyoshi Yamamoto

A load break detection circuit for detecting a break in a load connected to an output terminal of an output circuit includes a target voltage generator, a reference voltage generator, and a comparator. The reference voltage generator generates a reference voltage and a command value. When the output terminal is open-circuited, a flyback voltage is applied to the output terminal and the target voltage generator outputs a target voltage equal to the command value to the output terminal. The target voltage generator includes a voltage divider for dividing an output voltage appearing at the output terminal. The comparator compares the divided voltage with the reference voltage and outputs a load break detection signal based on a result of the comparison.

Load break detection circuit

A power control circuit is provided in a vehicle control ECU mounted in a vehicle. The control circuit, when making a shift to a test mode by a test mode circuit, closes a relay to supply a power voltage from a battery to a power line in the similar manner as an ignition main switch is turned on. A logic circuit section of the test mode circuit is reset by an OR logic of a set level of a test terminal and a level of the power line.

Test mode circuit and reset control method therefor

A series-regulator type of power supply circuit is provided. In the circuit, the emitter and collector of a transistor are connected to power input/output terminals. A control circuit controls a base current of the transistor based on the output voltage detected at the power output terminal and a given target voltage. A resistor circuit connects the base and the collector of the transistor. A bypass circuit connects the emitter and the base of the transistor and passes a bypass current. The accepting circuit connected to the power output terminal accepts (absorbs) current from an output current. An amount of the acceptance current is equal to or larger than an amount of the bypass current and a product of the bypass current and a resistance value of the resistance circuit is equal to or more than a difference between a voltage at the power input terminal and the target voltage.

Power supply circuit with series regulator

A drive circuit that supplies electric power to an electric load from a DC electric source includes a pair of series-connected first and second MOSFETS of the same conduction type, a pair of clamp circuits respectively connected between the drains and gates of the first and second MOSFETS, a series circuit of a first resistor and a switch, a first test terminal; a second test terminal connected to a joint of the first and second MOSFETS, a third test terminal for operating the switch, a fourth test terminal connected a joint of the first resistor and the switch; and a second resistor connected between the gate of the second MOSFET and the first test terminal. The switch and the first resistor are connected between the gate and the source of the first MOSFET to close when the drive circuit is normally operated and to open when it is given a high voltage test.

Drive circuit and method of applying high voltage test thereon

A trapezoid signal generating circuit has a charging and discharging circuit for a capacitor to generate a trapezoid signal which has less change at its rising portion and falling portion. Current output circuits supply a charging current and a discharging current in accordance with a voltage outputted from a current control circuit, respectively. The current control circuit has a charging and discharging circuit similar to the charging and discharging circuit, and produces an output voltage. This voltage increases in accordance with a linear function for a period from a time point when an input signal changes its level to a time point when the voltage reaches a reference voltage, and decreases thereafter in accordance with a linear function. The current flowing into the capacitor also increases and decreases in accordance with the linear function, so that the terminal voltage of the capacitor increases and decreases in accordance with a quadratic function.

Trapezoid signal generating circuit

A constant voltage supplying circuit including an output transistor is connected to a power source line and an output terminal. A base-emitter voltage of the output transistor is detected by a voltage detecting circuit composed of a transistor. A current-outputting circuit for supplying a current determined based on the voltage detected by the voltage detector to a reference voltage supplying circuit is used in the constant voltage supplying circuit. The reference voltage is supplied to a base of the output transistor to cancel a base-emitter voltage of the output transistor and to equalize the output voltage to a voltage generated in a reference voltage generating element included in the reference voltage supplying circuit. In this manner, the output voltage is kept constant notwithstanding variation of output current.

Circuit for supplying constant voltage

The present invention discloses an output circuit, by which it is possible to reduce power consumption while maintaining maximum voltage value to be outputted at high level. In this output circuit, a charge-and-discharge circuit uses a terminal voltage Vc of a capacitor as a trapezoidal wave voltage, and a drive circuit drives an output transistor based on the terminal voltage Vc, and a voltage Vo equal to the terminal voltage Vc is outputted to the load. A voltage detection circuit detects an emitter voltage (Vc&plus;VF) of the transistor and generates an electric current proportional to the terminal voltage Vc. This electric current is turned to a base current of the output transistor via a variable current circuit. Therefore, a base current proportional to the output voltage Vo is supplied to the output transistor.

Output circuit

A power supply apparatus is provided for energizing an electronic control unit mounted on a vehicle having a battery and a starter switch. The apparatus includes a coil connected to the power supply line, and a switch which operates for selectively enabling a current to flow through the coil and cutting off the current through the coil. A control circuit operates for selectively changing the switch between an ON state and an OFF state when the starter switch assumes an ON position. The ON and OFF states alternate in accordance with predetermined delays.

Growing community of inventors

Anjo, Japan

Akio Kojima