| 摘要 |
PROBLEM TO BE SOLVED: To improve operating characteristics by preventing a setting value for operating an overcurrent protection function from changing due to the change in an input voltage Vin, and flattening an overcurrent protection setting value over the entire region of Vin. SOLUTION: A voltage generated at a resistor 25 connected between the source and ground of an FET 24 is divided by a resistor 35, an FET 40, and the synthesis resistance of resistors 41 and 42. The negative bias voltage of a reference power supply 38 through a resistor 37 and Vin through a resistor 36 in advance is given to the gate of the FET 40. When Vin is low, the gate voltage of the FET 40 is reduced and the internal resistance is reduced. Conversely, when Vin is high, the gate voltage of the FET 40 is increased and the internal resistance is increased, thus reducing a signal current Vcur inputted to a control circuit 31 when Vin is low, increasing the overcurrent protection setting value, increasing Vcur when Vin is high, and reducing the overcurrent protection setting value. |
