Power Down Mode

During a rapid power-down conditiona, as would

occur with a power supply short circuit or with a

could discharge into Pin 2 or 14. To Avoid possible

≤0.5micro-

farad, a aprotection diode with a 1 Ampere or higher

rating (1N5395 or equivalent) and a separate

in Fig. 1

An alternate protection method is shown in Fig. 2,

where a 51

Ω current limit resistor is inserted in

series with CX. Note that a small pulse width de-

crease will occour however, and RX must be appro-

priately increased to obtain the originally desired

pulse width.

Figure 1: rapid Power Down Protection Circuit

Figure 2: Alternate rapid Power Down Protection

Circuit

HCC/HCF4538B

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