| 摘要 |
In a load-driving apparatus with a FET (2) between a battery and a load (3), an overcurrent detection circuit has a function generation circuit (11) with a voltage divider circuit (12) and a comparator (13). The voltage divider circuit (12) has a pair of resistors (R1, R2) connected to a drain of the FET (2), and a Zener diode (ZD) connected to a connection point (P) in parallel to the second resistor (R2). The comparator (13) compares a reference voltage at the connection point with a variable voltage of the FET (2), and outputs an overcurrent detection signal when the variable voltage becomes lower than the reference voltage. When no overcurrent exists and the battery voltage is not decreasing, the connection point is kept at a breakdown voltage of the Zener diode (ZD), and the difference with respect to the source voltage of the FET (2) becomes particularly large. The comparator (13) therefore does not erroneously output an overcurrent detection signal even when noise enters the system. |
