JAJSVA4B November 2004 – August 2024 CD74HC4538-Q1
PRODUCTION DATA
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During a rapid power-down condition (as would occur with a power-supply short circuit with a poorly filtered power supply), the energy stored in CX could discharge into pin 2 or pin 14. To avoid possible device damage in this mode when CX is \u0001 0.5 µF, a protection diode with a 1-A rating or higher (1N5395 or equivalent) and a separate ground return for CX should be provided. Rapid-Power-Down Protection Circuit
An alternate protection method is shown in Alternative Rapid-Power-Down Protection Circuit, where a 51-Ω current-limiting resistor is inserted in series with CX . Note that a small pulse-duration decrease occurs, however, and RX must be increased appropriately to obtain the originally desired pulse duration.