5-341
FAST AND LS TTL DATA
PRESETTABLE BCD/DECADE
UP/DOWN COUNTERS
PRESETTABLE 4-BIT BINARY
UP/DOWN COUNTERS
The SN54/74LS190 is a synchronous UP/DOWN BCD Decade (8421)
Counter and the SN54/74LS191 is a synchronous UP/DOWN Modulo-16
Binary Counter. State changes of the counters are synchronous with the
LOW-to-HIGH transition of the Clock Pulse input.
An asynchronous Parallel Load (PL) input overrides counting and loads the
data present on the P
n
inputs into the flip-flops, which makes it possible to use
the circuits as programmable counters. A Count Enable (CE) input serves as
the carry/borrow input in multi-stage counters. An Up/Down Count Control
(U
/D) input determines whether a circuit counts up or down. A Terminal Count
(TC) output and a Ripple Clock (RC
) output provide overflow/underflow
indication and make possible a variety of methods for generating
carry/borrow signals in multistage counter applications.
• Low Power . . . 90 mW Typical Dissipation
• High Speed . . . 25 MHz Typical Count Frequency
• Synchronous Counting
• Asynchronous Parallel Load
• Individual Preset Inputs
• Count Enable and Up/Down Control Inputs
• Cascadable
• Input Clamp Diodes Limit High Speed Termination Effects
NOTE:
The Flatpak version
has the same pinouts
(Connection Diagram) as
the Dual In-Line Package.
CONNECTION DIAGRAM DIP (TOP VIEW)
PIN NAMES LOADING (Note a)
HIGH LOW
CE
CP
U
/D
PL
P
n
Q
n
RC
TC
Count Enable (Active LOW) Input
Clock Pulse (Active HIGH going edge) Input
Up/Down Count Control Input
Parallel Load Control (Active LOW) Input
Parallel Data Inputs
Flip-Flop Outputs (Note b)
Ripple Clock Output (Note b)
Terminal Count Output (Note b)
1.5 U.L.
0.5 U.L.
0.5 U.L.
0.5 U.L.
0.5 U.L.
10 U.L.
10 U.L.
10 U.L.
0.7 U.L.
0.25 U.L.
0.25 U.L.
0.25 U.L.
0.25 U.L.
5 (2.5) U.L.
5 (2.5) U.L.
5 (2.5) U.L.
NOTES:
a. 1 TTL Unit Load (U.L.) = 40 µA HIGH/1.6 mA LOW.
b. The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74)
b. Temperature Ranges.
SN54/74LS190
SN54/74LS191
PRESETTABLE BCD/DECADE
UP/DOWN COUNTERS
PRESETTABLE 4-BIT BINARY
UP/DOWN COUNTERS
LOW POWER SCHOTTKY
J SUFFIX
CERAMIC
CASE 620-09
N SUFFIX
PLASTIC
CASE 648-08
16
1
16
1
ORDERING INFORMATION
SN54LSXXXJ Ceramic
SN74LSXXXN Plastic
SN74LSXXXD SOIC
16
1
D SUFFIX
SOIC
CASE 751B-03
LOGIC SYMBOL
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