| 摘要 |
PURPOSE:To enable the use of either a 1.5V oxidized silver cell and a 3.0V lithium cell, by a method wherein a power source circuit in LSI is switched to either of a step-up circuit and a step-down circuit through the changing of connection of a cell and capacitor. CONSTITUTION:In case a lithium cell Li is used, the lithium cell Li is connected to the intermediate of VDD-VEE, and capacitors C1 and C2 are connected to the intermediates of VDD-VEE and DDC-Vc, respectively. MOS transistors Tr1-Tr4 switch the capacitors C1 and C2 to series and parallel, and the voltage of the lithium cell Li, which is reduced to 1/2, is obtained at a VSS terminal. In case an oxidized silver cell Ag2O is used, the cell and the capacitor C1 and C2 are connected as shown in Fig, and the voltage, which is stepped up to 2 times the cell voltage of the oxidized silver cell, is produced from the VEE terminal. In case the lithium cell is used, a transistor Tr5 forces the capacitor C1 to be charged, and this prevents a whole system from no working at a time when a power source is turned ON. |
