| 摘要 |
PROBLEM TO BE SOLVED: To protect a semiconductor element surely against thermal breakdown by arranging a heat-sensitive element part for detecting the heating state of a semiconductor power element between the regions for forming the semiconductor power element in a semiconductor chip. SOLUTION: When the temperature of a silicon substrate, and thereby the temperature at the junction of a power MOS 13, is normal, the power MOS 13 is turned on by an applying voltage Vin. When the temperature at the junction of the power MOS 13 increases, forward voltage of a polycrystalline silicon diode 15 in a heat-sensitive element drops because it has a constant negative temperature coefficient. Consequently, the voltage between the terminals of a resistor 16c increases and when it reaches a predetermined level, a lateral MOS transistor 14 is turned on. When the resistance of a resistor 16b is set sufficiently higher than the on resistance of the lateral MOS transistor 14, voltage of 22 drops abruptly at a protective operation temperature. Consequently, the power MOS 13 is turned off forcibly and a semiconductor element is protected surely against thermal breakdown. |
