SN54LV221A, SN74LV221A

DUAL MONOSTABLE MULTIVIBRATORS

WITH SCHMITT TRIGGER INPUTS

SCLS450G − DECEMBER 1999 − REVISED APRIL 2005

10

POST OFFICE BOX 655303

APPLICATION INFORMATION

caution in use

power-down considerations

stored in the capacitor. When a system containing this device is powered down, the capacitor can discharge

t = (5 V)

× (15 pF)/30 mA = 2.5 ns. Usually, this is not a problem because power supplies are heavily filtered

damage. To avoid this possibility, use external clamping diodes.

output pulse duration

VCC

RT

CT

To Rext/Cext

Terminal

To Cext

Terminal

Figure 2. Timing-Component Connections

The pulse duration is given by:

+ K

R

T

C

T

or

where:

K

= multiplier factor

Equation 1 and Figure 3 or 4 can be used to determine values for pulse duration, external resistance, and

external capacitance.

(1)