| 摘要 |
PROBLEM TO BE SOLVED: To obtain a switching power supply circuit having a multi-output power supply voltage system and capable of shutting down the whole power supply when high power supply voltage drops and approaches low power supply voltage. SOLUTION: The multi-output type switching power supply circuit is constituted of a high output power supply 5 V system and a low output power supply voltage 3.3 V system and the 5 V system is constituted of a three-terminal regulator 144 having a shunt regulator function. When the output of the 5 V system becomes an overload state, its output voltage is dropped and may be reduced lower than the output voltage of the 3.3 V system, the power supply is shut down interlocking with an overcurrent protection circuit 151 in the 3.3 V system. Consequently a unit to which power supply voltage is to be applied can be prevented from being damaged due to the latch-up phenomenon of a two-power supply type semiconductor.
|
