NTE74LS221 Multivibrator Datasheet

NTE74LS221 Datasheet PDF, Equivalent


Part Number

NTE74LS221

Description

Dual Monostable Multivibrator

Manufacture

NTE

Total Page 4 Pages
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NTE74LS221
NTE74LS221
Integrated Circuit
TTL Dual Monostable Multivibrator
Description:
The NTE74LS221 is a monolithic dual multivibrator in a 16Lead plastic DIP type package with per-
formance characteristics virtually identical to those of the NTE74121. Each multivibrator features a
negativetransitiontriggered input and a positivetransitiontriggered input either of which can be
used as an inhibit input.
Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of
the input pulse. Schmitttrigger input circuitry (TTL hysteresis) for B input allows jitterfree triggering
from inputs with transition rates as slow as 1 volt/second, providing the circuit with excellent noise
immunity of typically 1.2 volts. A high immunity to VCC noise of typically 1.5V is also provided by intern-
al latching circuitry.
Once fired, the outputs are independent o further transitions of the A an B inputs and are a function of the
timing components, or the output pulses can be terminated by the overriding clear. Input pulses may be of
any duration relative to the output pulse. Output pulse length may be varied from 35ns to the maximum pulse
length of 70 seconds by choosing appropriate timing components. With Rext = 2kand Cext = 0, and output
pulse of typically 30ns is achieved which may be used as a DC triggered reset signal. Output rise and fall
times are TTL compatible and independent of pulse length.
Pulse width stability is achieved through internal compensation and is virtually independent of VCC
and temperature. In most applications, pulse stability will only be limited by the accuracy of external
timing components.
Jitterfree operation is maintained over the full temperature and VCC ranges for more than six decades
of timing capacitance (10pF to 10F) and more than one decade of timing resistance (2kto
100k).Throughout these ranges, pulse width is defined by the relationship: tw(out) = CextRext In2 [ 0.7
CextRext. In circuits where the pulse cutoff is not critical, timing capacitance up to 1000F and timing resist-
ance as low as 1.4kmay be used. Also, the range of jitterfree output pulse widths is extended if VCC
is held to 5V and freeair temperature is +25C. Duty cycles as high as 90% are achieved when using
maximum recommended RT. Higher duty cycles are available if a certain amount of pulsewidth jitter is
allowed.
Features:
D Overriding Clear Terminates Output Pulse

NTE74LS221
Recommended Operating Conditions:
Parameter
Supply Voltage
HighLevel Output Current
LowLevel Output Current
Rate of Rise or Fall of Input Pulse
Input Pulse Width
Clear InactiveState Setup Time
External Timing Resistance
External Timing Capacitance
Output Duty Cycle
Operating Temperature Range
Symbol Min Typ Max Unit
Schmitt, B
Logic Input, A
VCC 4.75 5.0 5.25 V
IOH − − −400 A
IOL − − 8 mA
dv/dt 1 − − V/s
1 − − V/s
A or B
Clear
RT = 2k
RT = MAX Rext
tw(in)
tw(clear)
tsu
Rext
Cext
TA
50
40
15
1.4
0
0
− − ns
− − ns
− − ns
100 k
1000 F
50 %
90 %
+70 C
Electrical Characteristics: (Note 1, Note 2)
Parameter
Symbol
Test Conditions
Threshold Voltage at A Input VT+ VCC = MIN
VT
Threshold Voltage at B Input VT+ VCC = MIN
VT
Input Clamp Voltage
VIK VCC = MIN, II = 18mA
High Level Output Voltage
VOH VCC = MIN, IOH = 400A
Low Level Output Voltage
VOL VCC = MIN
Input Current
High Level Input Current
Low Level Input Current
II VCC = MAX, VI = 7V
IIH VCC = MAX, VI = 2.7V
IIL VCC = MAX, VI = 0.4V
ShortCircuit Output Current IOS VCC = MAX, Note 3
Supply Current
ICC VCC = MAX
IOL = 4mA
IOL = 8mA
Input A
Input B
Clear
Quiescent
Triggered
Min Typ Max Unit
1.0 2.0 V
0.8 1.0
V
1.0 2.0 V
0.8 0.9
V
− − −1.5 V
2.7 3.4
V
0.25 0.4 V
0.35 0.5 V
− − 0.1 mA
− − 20 A
− − −0.4 mA
− − −0.8 mA
− − −0.8 mA
20 − −100 mA
4.7 11 mA
19 27 mA
Note 1. .For conditions shown as MIN or MAX, use the appropriate value specified under “Recommended
Operation Conditions”.
Note 2. All typical values are at VCC = 5V, TA = +25C.
Note 3. Not more than one output should be shorted at a time and duration of shortcircuit should
not exceed one second.


Features NTE74LS221 Integrated Circuit TTL − Du al Monostable Multivibrator Description : The NTE74LS221 is a monolithic dual m ultivibrator in a 16−Lead plastic DIP type package with performance characte ristics virtually identical to those of the NTE74121. Each multivibrator featu res a negative−transition−triggered input and a positive−transition−tr iggered input either of which can be us ed as an inhibit input. Pulse triggerin g occurs at a particular voltage level and is not directly related to the tran sition time of the input pulse. Schmitt −trigger input circuitry (TTL hystere sis) for B input allows jitter−free t riggering from inputs with transition r ates as slow as 1 volt/second, providin g the circuit with excellent noise immu nity of typically 1.2 volts. A high imm unity to VCC noise of typically 1.5V is also provided by internal latching cir cuitry. Once fired, the outputs are ind ependent o further transitions of the A an B inputs and are a function of the timing components, or the output pulses .
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