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DM74ALS163BN

Part # DM74ALS163BN
Description IC COUNTER BIN SYNC 4BIT 16-DIP
Category IC
Availability In Stock
Qty 61
Qty Price
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Manufacturer Available Qty
National Semiconductor Corp
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Technical Document


DISCLAIMER: The information provided herein is solely for informational purposes. Customers must be aware of the suitability of this product for their application, and consider that variable factors such as Manufacturer, Product Category, Date Codes, Pictures and Descriptions may differ from available inventory.

© 2000 Fairchild Semiconductor Corporation DS006206 www.fairchildsemi.com
April 1984
Revised February 2000
DM74ALS161B • DM74ALS162B • DM74ALS163B Synchronous Four-Bit Counter
DM74ALS161B • DM74ALS162B • DM74ALS163B
Synchronous Four-Bit Counter
General Description
These synchronous presettable counters feature an inter-
nal carry look ahead for application in high speed counting
designs. The DM74ALS162B is a four-bit decade counter,
while the DM74ALS161B and DM74ALS163B are four-bit
binary counters. The DM74ALS161B clears asynchro-
nously, while the DM74ALS162B and DM74ALS163B clear
synchronously. The carry output is decoded to prevent
spikes during normal counting mode of operation. Synchro-
nous operation is provided by having all flip-flops clocked
simultaneously so that outputs change coincident with
each other when so instructed by count enable inputs and
internal gating. This mode of operation eliminates the out-
put counting spikes which are normally associated with
asynchronous (ripple clock) counters. A buffered clock
input triggers the four flip-flops on the rising (positive-
going) edge of the clock input waveform.
These counters are fully programmable, that is, the outputs
may be preset to either level. As presetting is synchronous,
setting up a low level at the load input disables the counter
and causes the outputs to agree with set up data after the
next clock pulse regardless of the levels of enable input.
LOW-to-HIGH transitions at the load input are perfectly
acceptable regardless of the logic levels on the clock or
enable inputs.
The DM74ALS161B clear function is asynchronous. A low
level at the clear input sets all four of the flip-flop outputs
LOW regardless of the levels of clock, load or enable
inputs. These two counters are provided with a clear on
power-up feature. The DM74ALS162B and DM74ALS163B
clear function is synchronous; and a low level at the clear
input sets all four of the flip-flop outputs LOW after the next
clock pulse, regardless of the levels of enable inputs. This
synchronous clear allows the count length to be modified
easily, as decoding the maximum count desired can be
accomplished with one external NAND gate. The gate out-
put is connected to the clear input to synchronously clear
the counter to all low outputs. LOW-to-HIGH transitions at
the clear input of the DM74ALS162B and DM74ALS163B
are also permissible regardless of the levels of logic on the
clock, enable or load inputs.
The carry look ahead circuitry provides for cascading
counters for n bit synchronous application without addi-
tional gating. Instrumental in accomplishing this function
are two count enable inputs (P and T) and a ripple carry
output. Both count enable inputs must be HIGH to count.
The T input is fed forward to enable the ripple carry output.
The ripple carry output thus enabled will produce a high
level output pulse with a duration approximately equal to
the high level portion of QA output. This high level overflow
ripple carry pulse can be used to enable successive cas-
caded stages. HIGH-to-LOW level transitions at the enable
P or T inputs of the DM74ALS161B through
DM74ALS163B may occur regardless of the logic level on
the clock.
The DM74ALS161B through DM74ALS163B feature a fully
independent clock circuit. changes made to control inputs
(enable P or T, or load) that will modify the operating mode
will have no effect until clocking occurs. The function of the
counter (whether enabled, disabled, loading or counting)
will be dictated solely by the conditions meeting the stable
set-up and hold times.
Features
Switching specifications at 50 pF
Switching specifications guaranteed over full tempera-
ture and V
CC
range
Advanced oxide-isolated, ion-implanted Schottky TTL
process
Functionally and pin-for-pin compatible with Schottky
and low power Schottky TTL counterpart
Improved AC performance over Schottky and low power
Schottky counterparts
Synchronously programmable
Internal look ahead for fast counting
Carry output for n-bit cascading
Synchronous counting
Load control line
ESD inputs
Ordering Code:
Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Order Number Package Number Package Description
DM74ALS161BM M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74ALS161BN N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
DM74ALS162BM M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74ALS162BN N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
DM74ALS163BM M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
DM74ALS163BN N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
www.fairchildsemi.com 2
DM74ALS161B • DM74ALS162B • DM74ALS163B
Connection Diagram Mode Select Table
H = HIGH Voltage Level
L = LOW Voltage Level
X = Immaterial
Logic Diagrams
DM74ALS161B
Clear Load Enable T Enable P
Action on the Rising
Clock Edge (
)
L X X X Reset (Clear)
H L X X Load (P
n
Q
n
)
H H H H Count (Increment)
H H L X No Change (Hold)
H H X L No Change (Hold)
3 www.fairchildsemi.com
DM74ALS161B • DM74ALS162B • DM74ALS163B
Logic Diagrams (Continued)
DM74ALS162B
DM74ALS163B
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