| 摘要 |
An input voltage is applied by an NMOS transistor ( 34 ) driven by an oscillation circuit ( 60 ) to a primary winding ( 32 a) of a transformer ( 32 ) intermittently. A voltage induced in a secondary winding ( 32 b) is rectified and smoothed by an output circuit ( 91 ) to be an output voltage. In a normal mode where no standby signal is supplied, the oscillation circuit ( 60 ) controls the NMOS transistor ( 34 ) so that the output voltage is stabilized at a predetermined first value. When a standby signal is supplied, a detection circuit ( 100 ) detects the standby signal and transmits the detection to a starting circuit ( 40 ). The starting circuit ( 40 ) starts the oscillation circuit ( 60 ) when a voltage of a capacitor ( 33 ) reaches an upper limit, and stops the oscillation circuit ( 60 ) when this voltage lowers below a lower limit. This upper limit is lower than an upper limit at which the starting circuit ( 40 ) starts the oscillation circuit ( 60 ) in the normal mode.
|
