Delay circuit

A delay circuit for charging/discharging a capacitor to set a delay time, comprising:

• a capacitor;
• a circuit for controlling the charging and discharging of the capacitor in accordance with an input signal;
• and a comparator for comparing a voltage at a first terminal of the capacitor with at least a first reference voltage and a second reference voltage higher than the first reference voltage and producing an output signal in accordance with the comparison result;
• wherein the circuit for controlling the charging and discharging of the capacitor comprises a voltage source to which the first terminal of the capacitor is connected to provide a charging path for charging the capacitor, and a discharging path connected to the capacitor for discharging the capacitor.

A delay circuit comprising:

• a first circuit for charging/discharging a capacitor to set a delay time in accordance with a capacitance value of the capacitor and having a voltage source to which a first terminal of the capacitor is connected to provide a charging path for charging the capacitor, a discharging path connected to the capacitor for discharging the capacitor, and a first comparing circuit for comparing a voltage at one of the terminals of the capacitor to a first reference voltage and producing an output signal in accordance with the comparison result;
• a second circuit operative when one terminal of the capacitor becomes one of short-circuited to an abnormal voltage level, open-circuited, and short-circuited to an improper wiring line to reduce the delay time;
• a first switch disposed between the first terminal of the capacitor and the voltage source for controlling the charging of the capacitor;
• a second switch disposed in the discharging path for controlling the discharging of the capacitor;
• and
• a control circuit for receiving an input signal, producing a first output signal for controlling the first switch to control charging of the capacitor through the charging path in response to the input signal, and producing a second output signal for controlling the second switch to control discharging of the capacitor through the discharging path in response to the input signal.