TIMING_THRESHOLD_AND_LOAD_DRIVER

Published:2009/7/8 2:20:00 Author:May | From:SeekIC

Power is applied to the circuit with the initiate switch open. The 25-μF capacitor charges through the A14, or equivalent, diode and 2.2-KΩ resistor to full supply voltage. When the initiate switch is closed, the low side of the capacitor is suddenly raised to + 12 V. This raises the diode side of the capacitor to approximately +24 V. The capacitor immediately begins discharging through the seriesconnected 1 and 3.3-MΩ resistors. Eventually, the C13 gate becomes forward biased, the device tums, and it applies power to the relay. The delay is virtually independent of supply voltage.



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