Denso Corporation

Shouichi Okuda

Masahiko Ito

Tomohisa Ose

Yoshinori Arashima

A constant current control circuit is disclosed. Pads are connected with a common power supply terminal. Shunt resistors are located outward of a region containing Pch type MOS transistors. A temperature increase of the shunt resistors due to a temperature increase of the MOS transistors can be suppressed by the above structure. In particular, when the MOS transistor of one circuit system is driven, the shunt resistor of another circuit system is distant from the driving MOS transistor, and thus, it is possible to further suppress the temperature increase of the distant shunt resistor. Moreover, a power supply terminal can be provided as a single common terminal, and the number of terminals can be reduced.

Constant current control circuit

A load-driving circuit supplies electric current to a load, such as a resistor of an airbag squib. The load-driving circuit includes high side and low side current control circuits, both connected in series. Each current control circuit is composed of a driving transistor, a resistor and a current mirror circuit for controlling operation of the driving transistor. The components in the load-driving circuit are positioned in an integrated circuit chip to generate different temperature gradients among the components. For example, the low side resistor is positioned close to the high side driving transistor, so that the low side resistor is heated by the high side driving transistor controlled under a constant current control. As the low side resistor is heated, the high side driving transistor is switched from the constant current control to a full-on control. In this manner, controls of both driving transistors are automatically switched thereby to avoid overheating of one of the driving transistors.

Load-driving circuit having two transistors switched for heat dissipation

An electrical and electronic system includes an air-bag ECU and a squib. The air-bag ECU has a power supply circuit, an electronic element, a noise protection line, a switching element and a voltage detector. The noise protection line is connected between an element line, which is connected to the electronic element and the squib and to the ground. The switching element is connected to the noise protection line in series. When the voltage detector detects a large noise, it turns on the switching element to protect the electronic element from such a large noise.

Electrical and electronic system

A load drive device for driving an electrical load includes high-side and low-side transistors, and a switch. When the load is driven, each of the high-side and low-side transistors operates in a first mode where each of the high-side and low-side transistors is fully tuned on or in a second mode where each of the high-side and low-side transistors is controlled so that a load current flowing through the load is constant. When the load is driven, there is a first state where the high-side transistor operates in the second mode and the low-side transistor operates in the first mode and a second state where the high-side transistor operates in the first mode and the low-side transistor operates in the second mode. The switch switches between the first and second states to distribute heat generation between the high-side and low-side transistors.

Electrical load drive device

A semiconductor device includes: a semiconductor substrate having first and second pads; an output transistor; and a current control circuit having first and second resistors, a control signal generation circuit, first and second switching circuits. The first or second resistor is disposed between the first or second pad and the output transistor. The control signal generation circuit generates a control signal to the output transistor based on a voltage of both ends of the first or second resistor. The first or second switching circuit is disposed between both ends of the first or second resistor and the control signal generation circuit. The first or second switching circuit is controlled to be in an on-state.

Growing community of inventors

Nukata-gun, Japan

Shouichi Okuda