| 摘要 |
PURPOSE:To make the device small-sized and inexpensive, by using an output detecting part for protection from overcurrent to switch the operation of a switching regulator to the constant current operation and the constant voltage operation. CONSTITUTION:A changeover switch S for the constant voltage operation and the constant current operation supplies a high-level voltage (the first position b) to transistors TRs Tr1, Tr2, and Tr3 in case of a constant current and supplies a low-level voltage (the second position c) to them in case of a constant voltage. When the switch S is switched to the position c, the output is generated from the time when the voltage of a terminal i of a switching controlling circuit 2 becomes lower than that of a terminal j, and the output voltage is controlled in the direction where it is reduced. When the switch S is switched to the position b, the output voltage is controlled in the direction, where it is reduced, to obtain the constant current operation if the output current exceeds a value set in the terminal i. |
