JPS5728343A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To make it possible to use cells of different electromotive forces for the same IC, e.g. for clocks, by using for a power source a circuit capable of changeover between step up and down of an electromotive force, and selectively connecting a cell to the low-potential side terminal or the high-potential side terminal of the circuit. CONSTITUTION:A clock IC is composed of a low potential system circuit block 1 consisting of, for example, an oscillating circuit 4 and a frequency divider circuit 5, a hgih potential system circuit block 2 consisting of a clock circuit 6 and a liquid crystal display apparatus 7, a voltage generating circuit 3 having a low potential terminal 8 and a high potential terminal 9. The circuit 3 consists of switching FETs T1-T4 and external capacitors C1, C2. For example, when the capacitor C1, C2 of the same capacitance are connected as shown and a cell 10 is connected between VDD, VSS1, a voltage twice as large as the VSS1 at VSS2 is connected between VDD and VSS1 and the cell 10 between VDD and VSS2, a voltage half as much as VSS2 is generated at VSS1. Accordingly, changing-over the external position of the capacitor C2 and the connecting terminal of the cell 10 makes it possible to use the same IC for both, e.g. a silver cell and a lithium cell of different electromotive forces.