Philips Semiconductors
Product specification
Quadruple 2-input NAND Schmitt trigger
HEF4093B
gates
Fig.9 Typical switching levels as a function of supply voltage V
DD
; T
amb
= 25
°C.
APPLICATION INFORMATION
Some examples of applications for the HEF4093B are:
•
Wave and pulse shapers
•
Astable multivibrators
•
Monostable multivibrators.
Fig.10 The HEF4093B used as a astable multivibrator.
Fig.11 Schmitt trigger driven via a high impedance
(R
>
1 kΩ).
If a Schmitt trigger is driven via a high impedance (R > 1 kΩ) then it is necessary to incorporate a capacitor C of such
value that:
C V
DD
–
V
SS
------
>
--------------------------
, otherwise oscillation can occur on the edges of a pulse.
-
-
V
H
C
p
C
p
is the external parasitic capacitance between inputs and output; the value depends on the circuit board layout.
Note
The two inputs may be connected together, but this will result in a larger through-current at the moment of switching.
January 1995
6
PHILIPS [ NXP SEMICONDUCTORS ]
