Abstract: The present invention relates to an improvement in an EL driver including a second power supply voltage producer for producing second supply voltage for use in driving an EL lamp using a battery serving as a first power source, a third supply voltage producer for producing third supply voltage that is higher than the first supply voltage and lower than the second supply voltage, and a driving signal supplier for supplying an AC driving signal to an EL driving means when driven by the third supply voltage. The level of the AC driving signal is increased in two steps. The EL driver semiconductor device characteristic of the high-voltage efficiency and high threshold voltage can therefore be driven by low voltage.

Abstract: A voltage detecting circuit, for example for detecting the approaching exhaustion of the battery of a timepiece, hand-held calculator or other small electronic device uses a MOS transistor, the operating point of which in detecting the predetermined voltage is selected as the point at which the ratio of the current to the conductive constant of the MOS transistor is above 0.1. The temperature compensation thereby achieved is good enough that the measured value almost coincides with the design value without the need of using a variable resistor.