September 1986
Revised March 2000
DM74LS193
Synchronous 4-Bit Binary Counter with Dual Clock
of the count and load inputs. The clear, count, and load
inputs are buffered to lower the drive requirements of clock
drivers, etc., required for long words.
General Description
The DM74LS193 circuit is a synchronous up/down 4-bit
binary counter. Synchronous operation is provided by hav-
These counters were designed to be cascaded without the
ing all flip-flops clocked simultaneously, so that the outputs
need for external circuitry. Both borrow and carry outputs
change together when so instructed by the steering logic.
are available to cascade both the up and down counting
This mode of operation eliminates the output counting
functions. The borrow output produces a pulse equal in
spikes normally associated with asynchronous (ripple-
width to the count down input when the counter underflows.
clock) counters.
Similarly, the carry output produces a pulse equal in width
The outputs of the four master-slave flip-flops are triggered
to the count down input when an overflow condition exists.
by a LOW-to-HIGH level transition of either count (clock)
The counters can then be easily cascaded by feeding the
input. The direction of counting is determined by which
borrow and carry outputs to the count down and count up
count input is pulsed while the other count input is held
inputs respectively of the succeeding counter.
HIGH.
The counter is fully programmable; that is, each output may
Features
be preset to either level by entering the desired data at the
■ Fully independent clear input
inputs while the load input is LOW. The output will change
independently of the count pulses. This feature allows the
counters to be used as modulo-N dividers by simply modi-
fying the count length with the preset inputs.
■ Synchronous operation
■ Cascading circuitry provided internally
■ Individual preset each flip-flop
A clear input has been provided which, when taken to a
high level, forces all outputs to the low level; independent
Ordering Code:
Order Number Package Number
Package Description
DM74LS193M
M16A
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow Body
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide
DM74LS193N
N16E
Connection Diagram
© 2000 Fairchild Semiconductor Corporation
DS006406
www.fairchildsemi.com