Circuito electrónico

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Decade and Binary Counters
General Description
Each of these monolithic counters contains four masterslave
flip-flops and additional gating to provide a divide-bytwo
counter and a three-stage binary counter for which the
count cycle length is divide-by-five for the 'LS90 and divideby-
eight for the 'LS93.
All of these counters have a gated zero reset and theLS90
also has gated set-to-nine inputs for use in BCD nine's complement
To use their maximum count length (decade or four bit binary),
the B input is connected to the QA output. The input
count pulses are applied to input A and the outputs are as
described in the appropriate truth table. A symmetrical divide-
by-ten count can be obtained from the 'LS90 counters
by connectingthe QD output to the A input and applying the
input count to the B input which gives a divide-by-ten square
wave at output QA.
Y Typical power dissipation 45 mW
Y Count frequency 42 MHz
Connection Diagrams (Dual-In-Line Packages)
Order Number DM74LS90M or DM74LS90N
See NS Package Number M14A or N14A
Order Number DM74LS93M or DM74LS93N
See NS PackageNumber M14A or N14A
C1995 National Semiconductor Corporation RRD-B30M105/Printed in U. S. A.
Absolute Maximum Ratings (Note)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage 7V
Input Voltage (Reset) 7V
Input Voltage (A or B) 5.5V
Operating Free Air Temperature RangeDM74LS 0ßC to a70ßC
Storage Temperature Range b65ßC to a150ßC
Note: The ``Absolute Maximum Ratings'' are those values
beyond which the safety of the device cannot be guaranteed.
The device should not be operated at these limits. The
parametric values defined in the ``Electrical Characteristics''
table are not guaranteed at the absolute maximum ratings.
The ``Recommended Operating Conditions''table will define
the conditions for actual device operation.
Recommended Operating Conditions
Symbol Parameter
Min Nom Max
VCC Supply Voltage 4.75 5 5.25 V
VIH High Level Input Voltage 2 V
VIL Low Level Input Voltage 0.8 V
IOH High Level Output Current b0.4 mA
IOL Low Level Output Current 8 mA
fCLK Clock Frequency (Note 1) A to QA 0 32
B to QB 0 16
fCLK ClockFrequency (Note 2) A to QA 0 20
B to QB 0 10
tW Pulse Width (Note 1) A 15
B 30 ns
Reset 15
tW Pulse Width (Note 2) A 25
B 50 ns
Reset 25
tREL Reset Release Time (Note 1) 25 ns
tREL Reset Release Time (Note 2) 35 ns
TA Free Air Operating Temperature 0 70 ßC
Note 1: CL e 15 pF, RL e 2 kX, TA e 25ßC and VCC e 5V.
Note 2: CL e 50 pF, RL e 2 kX, TA e 25ßC and VCC e 5V.
'LS90 ElectricalCharacteristics
over recommended operating free air temperature range (unless otherwise noted)
Symbol Parameter Conditions Min
Max Units
(Note 1)
VI Input Clamp Voltage VCC e Min, IIe b18 mA b1.5 V
VOH High Level Output VCC e Min, IOH e Max
2.7 3.4 V
Voltage VIL e Max, VIH e Min
VOL Low Level Output VCC e Min, IOL e Max
Voltage VIL e Max, VIH e Min 0.35 0.5
(Note 4)
IOL e 4 mA,VCC e Min 0.25 0.4
II Input Current @ Max VCC e Max, VI e 7V Reset 0.1
Input Voltage
VCC e Max A 0.2 mA
VI e 5.5V
B 0.4
'LS90 Electrical Characteristics
over recommended operating free air temperature range (unless otherwise noted) (Continued)
Symbol Parameter Conditions Min
Max Units
(Note 1)
IIH High Level Input VCC e Max, VI e 2.7V Reset 20
A 40mA
B 80
IIL LowLevel Input VCC e Max, VI e 0.4V Reset b0.4
A b2.4 mA
B b3.2
IOS Short Circuit VCC e Max (Note 2)
b20 b100 mA
Output Current
ICC Supply Current VCC e Max (Note 3) 9 15 mA
Note 1: All typicals are at VCC e 5V, TA e 25ßC.
Note 2: Not more than one output should be shorted at a time, and the duration should not exceed one second.
Note 3: ICC is measured with all outputs open, both...
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