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54LS169FMQB View Datasheet(PDF) - National ->Texas Instruments

Part NameDescriptionManufacturer
54LS169FMQB Synchronous 4-Bit Up/Down Binary Counter National-Semiconductor
National ->Texas Instruments National-Semiconductor
54LS169FMQB Datasheet PDF : 8 Pages
1 2 3 4 5 6 7 8
June 1989
54LS169 DM54LS169A DM74LS169A
Synchronous 4-Bit Up Down Binary Counter
General Description
This synchronous presettable counter features an internal
carry look-ahead for cascading in high-speed counting ap-
plications Synchronous operation is provided by having all
flip-flops clocked simultaneously so that the outputs all
change at the same time when so instructed by the count-
enable inputs and internal gating This mode of operation
helps eliminate the output counting spikes that are normally
associated with asynchronous (ripple clock) counters A
buffered clock input triggers the four master-slave flip-flops
on the rising edge of the clock waveform
This counter is fully programmable that is the outputs may
each be preset either high or low The load input circuitry
allows loading with the carry-enable output of cascaded
counters As loading is synchronous setting up a low level
at the load input disables the counter and causes the out-
puts to agree with the data inputs after the next clock pulse
The carry look-ahead circuitry permits cascading counters
for n-bit synchronous applications without additional gating
Both count-enable inputs (P and T) must be low to count
The direction of the count is determined by the level of the
up down input When the input is high the counter counts
up when low it counts down Input T is fed forward to en-
able the carry outputs The carry output thus enabled will
produce a low-level output pulse with a duration approxi-
mately equal to the high portion of the QA output when
counting up and approximately equal to the low portion of
the QA output when counting down This low-level overflow
carry pulse can be used to enable successively cascaded
stages Transitions at the enable P or T inputs are allowed
regardless of the level of the clock input All inputs are diode
clamped to minimize transmission-line effects thereby sim-
plifying system design
This counter features a fully independent clock circuit
Changes at control inputs (enable P enable T load up
down) which modify the operating mode 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 setup and hold
Y Fully synchronous operation for counting and
Y Internal look-ahead for fast counting
Y Carry output for n-bit cascading
Y Fully independent clock circuit
Y Alternate Military Aerospace device (54LS169) is
available Contact a National Semiconductor Sales
Office Distributor for specifications
Connection Diagram
Dual-In-Line Package
TL F 6401 – 1
Order Number 54LS169DMQB 54LS169FMQB 54LS169LMQB
DM54LS169AJ DM54LS169AW DM74LS169AM or DM74LS169AN
See NS Package Number E20A J16A M16A N16E or W16A
C1995 National Semiconductor Corporation TL F 6401
RRD-B30M105 Printed in U S A
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