Pc card and peripheral device

Abstract

Provided is a PC card and peripheral device having a non-volatile memory device that can perform erasing and re-writing at a relatively high operational voltage, and an internal circuit that is driven at a relatively low voltage, and is accomplished by a typical PC card that comprises: (a) an EEPROM serving as a non-volatile memory device; (b) a built-in battery having a low voltage output that supports the reading of the EEPROM but does not support erasing and re-writing; (c) a power line for conveying from a host computer system the high voltage required for erasing and re-writing the EEPROM; (d) an MPU that can be driven by a voltage supplied by the built-in battery; (e) an interface circuit that can be driven at a voltage supplied by the built-in battery; and (f) a switching circuit for selecting either the built-in battery or the power line as the power supply for the EEPROM. When the host computer system or the PC card access the EEPROM to read data, the switching circuit selects the built-in battery as the power source for the EEPROM. Then, an operational voltage that is adequate only for reading is supplied to the EEPROM. When the computer system accesses the EEPROM to write data, the switching circuit selects as the power source for the EEPROM the power line that conveys a high voltage. Therefore, the writing of data in the EEPROM can be performed.