SYNCHRONOUS 4-BIT UP/DOWN BINARY COUNTER
WITH DUAL CLOCK AND CLEAR
SDFS031A – D3693, JANUARY 1991 – REVISED OCTOBER 1993
• High-Speed fmax of 100 MHz Typical
• Parallel Asynchronous Load for Modulo-N
• Look-Ahead Circuitry Enhances Speed of
• Fully Synchronous in Count Modes
• Package Options Include Plastic
Small-Outline Packages and Standard
Plastic 300-mil DIPs
D OR N PACKAGE
The SN74F193A is a synchronous, 4-bit binary up/down counter. Synchronous counting operation is provided
by having all flip-flops clocked simultaneously so that the outputs change coincident with each other when so
instructed by the steering logic. This mode of operation eliminates the output counting spikes normally
associated with asynchronous (ripple-clock) counters.
The outputs of the four flip-flops are triggered on a low-to-high-level transition of either count /clock (UP or
DOWN) input. The direction of the count is determined by which count input is pulsed while the other count input
All four counters are fully programmable; that is, each output may be preset to either level by placing a low on
the LOAD input and entering the desired data at the data (D) inputs. The output will change to agree with the
data inputs independently of the count pulses. This feature allows the counters to be used as modulo-N dividers
by simply modifying the count length with the preset inputs.
A high level applied to the clear (CLR) input forces all outputs to the low level. The clear function is independent
of the count and load inputs.
These counters were designed to be cascaded without the need for external circuitry. The borrow (BO) output
produces a low-level pulse while the count is zero (all Q outputs low) and the DOWN input is low. Similarily, the
carry (CO) output produces a low-level pulse while the count is 15 (all Q outputs high) and the UP input is low.
The counters can then be easily cascaded by feeding the borrow and carry outputs to the count-down and
count-up inputs, respectively, of the succeeding counter.
The SN74F193A is characterized for operation from 0°C to 70°C.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
•POST OFFICE BOX 655303 DALLAS, TEXAS 75265
Copyright © 1993, Texas Instruments Incorporated