| 摘要 |
PURPOSE:To supply selectively a current from an auxiliary power supply by providing two reference voltage setting circuits, a voltage input terminal comparing reference voltages and a current source circuit supplying a current with an output of two voltage comparators. CONSTITUTION:A voltage as a result dividing an auxiliary power voltage 1 at resistors 4, 5, 6 is obtained from comparator reference voltage terminal sections 2, 3. Transistors (TRs) 8 and 9, 10 and 11 constitute a voltage comparator and TRs 14, 15 and 13, 16 are driven in response to the output. When a voltage at a line voltage detecting voltage terminal 7 is lower than the voltage at the terminal 3, the TR10 is turned off, no TR13 is activated then no current from the auxiliary power supply is applied. when the voltage at the terminal 7 is at a mid-level between the terminals 3 and 2, the TR10 is turned on and the TR8 is turned off, then the TR13 is activated and a current is applied from the terminal 7. When the voltage at the terminal 7 is higher than the voltage at the terminal 2, the TR10 is turned on and the TR8 is turned on, and then the TR12 is driven, the current supply from the TRs 13, 14, 15 is stopped. |
