DM74LS390 Dual 4-Bit Decade Counter
August 1986
Revised March 2000
DM74LS390
Dual 4-Bit Decade Counter
General Description
Each of these monolithic circuits contains eight master-
slave flip-flops and additional gating to implement two indi-
vidual four-bit counters in a single package. The
DM74LS390 incorporates dual divide-by-two and divide-
by-five counters, which can be used to implement cycle
lengths equal to any whole and/or cumulative multiples of 2
and/or 5 up to divide-by-100. When connected as a bi-qui-
nary counter, the separate divide-by-two circuit can be
used to provide symmetry (a square wave) at the final out-
put stage. The DM74LS390 has parallel outputs from each
counter stage so that any submultiple of the input count fre-
quency is available for system-timing signals.
Features
s
Dual version of the popular DM74LS90
s
DM74LS390...individual clocks for A and B flip-flops
provide dual
梅
2 and
梅
5 counters
s
Direct clear for each 4-bit counter
s
Dual 4-bit version can significantly improve system den-
sities by reducing counter package count by 50%
s
Typical maximum count frequency...35 MHz
s
Buffered outputs reduce possibility of collector commu-
tation
Ordering Code:
Order Number
DM74LS390M
DM74LS390N
Package Number
M16A
N16E
Package Description
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter 鈥淴鈥?to the ordering code.
Connection Diagram
漏 2000 Fairchild Semiconductor Corporation
DS006433
www.fairchildsemi.com
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