| 摘要 |
<p>PURPOSE:To prevent erroneous load control at power voltage drop by feeding power to a drive circuit via a switch circuit turned off when a voltage drop is detected by a detection circuit detecting the power supply voltage drop of a logic circuit. CONSTITUTION:Since a gate of an FET 8 of N-channel constitution is at a high potential at a normal power supply voltage, the FET 8 is turned on and drive circuits 3-1-3-n are driven by a signal from the logic circuit 2. Since the power supply to the drive circuits 3-1-3-n is cut off in this case, they are inactivated and a gate potential of output N-channel FETs 4-1-4-n is kept to an earth potential through resistors 11-1-11-n and no power is fed to heater resistors 5-1-5-n. Thus, an instable load control at a low power supply voltage is prevented and the deterioration of the characteristic of the load and drive elements due to heat dissipation through continuous power application is prevented.</p> |
