HCF4538B_01 Datasheet, PDF (2/10 Pages) STMicroelectronics – DUAL MONOSTABLE MULTIVIBRATOR

HCF4538B
from either edge of an input pulse. An unused +TR
input should be tied to V_SS. An unused -TR input
should be tied to V_DD . A RESET (on low level) is
provided for immediate termination of the output
pulse or to prevent output pulses when power is
turned on. An unused RESET input should be tied
to V_DD . However, if an entire section of the
HCF4538B is not used, its inputs must be tied to
either V_DD or V_SS (see table 1). In normal
operation the circuit triggers (extends the output
IINPUT EQUIVALENT CIRCUIT
FUNCTIONAL DIAGRAM
pulse one period) on the application of each new
trigger pulse. For operation in the non-retiggerable
mode, Q is connected to -TR when leading edge
triggering (+TR) is used or Q is connected to +TR
when trailing edge triggering (-TR) is used. The
time period (T) for this multivibrator can be
calculated by : T = R_X C_X. The min. value of
external resistance, R_X, is 4KΩ. The max. and
min. values of external capacitance, C_X, are 100
µF and 5nF, respectively.
PIN DESCRIPTION
PIN No
SYMBOL NAME AND FUNCTION
4, 12
+TR
Trigger Inputs (Low to
High, Edge-Triggered)
5, 11
-TR
Trigger Inputs (High to
Low, Edge-Triggered)
3, 13
RESET
Direct Reset Inputs
(Active Low)
1, 15
C_X1, C_X2
External Capacitor Con-
nections
2, 14
R_XC_X1
R_XC_X2
External Resistor/Capaci-
tor Connections
6, 10
Q1, Q2 Pulse Outputs
7, 9
Q1, Q2
Complementary Pulse
Outputs
8
V_SS
Negative Supply Voltage
16
V_DD
Positive Supply Voltage
Terminals 1, 8, 15 are electrically connected internally
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