POWER SUPPLY CIRCUIT OF REAL TIME CLOCK FOR COMPUTER SYSTEM

摘要

PURPOSE: A power supply circuit of real time clock for computer system is provided to extend the life of a battery for supplying a power to an RTC(Real Time Clock) by selectively providing a power by an auxiliary power and the battery to the RTC. CONSTITUTION: A battery(30) supplies a power to an RTC(10). A switching circuit(40) selectively supplies a power supplied from a power supply apparatus(20) and the battery(30) to the RTC(10). The power supply apparatus(20) receives an external power and supplies a main power(V_MAIN) and an auxiliary power(V_AUX) to a computer system. The power supply apparatus(20) is composed by a switching mode power supply(SMPS). The switching circuit(40) supplies the auxiliary power(V_AUX) outputted from the power supply apparatus(20) to the RTC(10) when a switch(SW1) is turned on and the external power is received. The switching circuit(40) supplies the battery power(V_BAT) provided from the battery(30) to the RTC(10) when a switch(SW1) is turned off and the external power is not received.