| 摘要 |
PURPOSE:To prevent a resetting miss by exercising control over resetting operation by the break voltage of a Zener diode. CONSTITUTION:Power source VSS is connected via Zener diode 5 and resistance 6 to the base of transistor 9, whose collector is connected to reset terminal RST of IC1; and power source VSS is connected to reset terminal RST via resistance 8 and the emitter of transistor 9 is grounded. When power voltage VSS is below a Zener voltage, transistor 9 is off and VSS is applied to reset terminal RST as it is. As VSS increases above the Zener voltage, a Zener break is made and transistor 9 turns on to hold the voltage of reset therminal RST at a low level. Meanwhile, the voltage passed through resistance 8 exceeds the threshold voltage and until transistor 9 turns on, the reset voltage is applied to reset terminal RST. |
