Operating Rules (Continued)

8. Output pulse width variation versus VCC and tempera-

tures: Figure 6 depicts the relationship between pulse

width variation versus VCC, and Figure 7 depicts pulse

width variation versus temperatures.

FIGURE 6.

FIGURE 7.

9. Under any operating condition CX and RX must be kept

as close to the one-shot device pins as possible to min-

imize stray capacitance, to reduce noise pick-up, and

to reduce I-R and Ldi/dt voltage developed along their

connecting paths. If the lead length from CX to pins (6)

and (7) or pins (14) and (15) is greater than 3 cm, for

example, the output pulse width might be quite different

from values predicted from the appropriate equations.

A non-inductive and low capacitive path is necessary to

ensure complete discharge of CX in each cycle of its

operation so that the output pulse width will be accu-

rate.

10. The CEXT pins of this device are internally connected to

the internal ground. For optimum system performance

they should be hard wired to the system’s return

ground plane.

11. VCC and ground wiring should conform to good high-

frequency standards and practices so that switching

transients on the VCC and ground return leads do not

cause interaction between one-shots. A 0.01

µF to 0.10

µF bypass capacitor (disk ceramic or monolithic type)

from VCC to ground is necessary on each device. Fur-

thermore, the bypass capacitor should be located as

close to the VCC-pin as space permits.

Note: For further detailed device characteristics and output per-

formance please refer to the Fairchild Semiconductor one-shot

application note AN-372.

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