SN54LS490 Datasheet, PDF (1/8 Pages) Motorola, Inc – DUAL DECADE COUNTER

SN54LS490, SN74LS490
DUAL 4-BIT DECADE COUNTERS
D Dual Versions of the SN54LS90 and
SN74LS90 Counters
D Individual Clock, Direct Clear, and Set-to-9
Inputs for Each Decade Counter
D Dual Counters Can Significantly Improve
System Densities as Package Count Can
Be Reduced by 50%
D Maximum Count Frequency of
25 MHz . . . 35 MHz Typical
D Buffered Outputs Reduce Possibility of
Collector Commutation
D Package Options Include Plastic
Small-Outline (D) Packages, Ceramic Flat
(W) Packages, Ceramic Chip Carriers (FK),
and Standard Plastic (N) and Ceramic (J)
DIPs
SDLS125A – OCTOBER 1976 – REVISED JULY 1998
SN54LS490 . . . J OR W PACKAGE
SN74LS490 . . . D OR N PACKAGE
(TOP VIEW)
1CLK 1
1CLR 2
1Q_A 3
1SET9 4
1Q_B 5
1Q_C 6
1Q_D 7
GND ⁸
16 V_CC
15 2CLK
14 2CLR
13 2Q_A
12 2SET9
11 2Q_B
10 2Q_C
9 _2QD
SN54LS490 . . . FK PACKAGE
(TOP VIEW)
description
Each of these monolithic circuits contains eight
master-slave flip-flops and additional gating to
implement two individual 4-bit decade counters in
a single package. Each decade counter has
individual clock (1CLK, 2CLK), clear (1CLR,
2CLR), and set-to-9 (1SET9, 2SET9) inputs. BCD
count sequences of any length up to
divide-by-100 can be implemented with a single
’LS490 device. Buffering on each output is
provided to significantly reduce susceptibility to
collector commutation. All inputs are diode
clamped to reduce the effects of line ringing. The
counters have parallel outputs from each counter
stage so that submultiples of the input count
frequency are available for system timing signals.
1Q_A
1SET9
NC
1Q_B
1Q_C
3 2 1 20 19
4
18
5
17
6
16
7
15
8
14
9 10 11 12 13
2CLR
2Q_A
NC
2SET9
2Q_B
NC – No internal connection
The SN54LS490 is characterized for operation over the full military temperature range of –55°C to 125°C.
The SN74LS490 is characterized for use in industrial systems operating from 0°C to 70°C.
CLEAR/SET-TO-9 FUNCTION TABLE
(each counter)
INPUTS
OUTPUTS
CLR SET9 QA QB QC QD
H
L
L
L
L
L
L
H
H
L
L
H
L
L
Count
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
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testing of all parameters.
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