SN54ALS193A, SN74ALS193A SYNCHRONOUS 4-BIT UP/DOWN BINARY COUNTERS WITH DUAL CLOCK AND CLEAR

SDAS211C - DECEMBER 1982 - REVISED JULY 1996

Please be aware that an important notice concerningavailability, standard warranty, and use in critical applications ofTexas Instruments semiconductor products and disclaimers theretoappears at the end of this data sheet.

features

• Look-Ahead Circuitry Enhances Cascaded Counters
• Fully Synchronous in Count Modes
• Parallel Asynchronous Load for Modulo-N Count Lengths
• Asynchronous Clear
• Package Options Include Plastic Small-Outline (D) Packages, Ceramic Chip Carriers (FK), and Standard Plastic (N) and Ceramic (J) 300-mil DIPs

description

The 'ALS193A are synchronous, reversible, 4-bit up/down binarycounters. Synchronous counting operation is provided by having allflip-flops clocked simultaneously so that the outputs changecoincident with each other when instructed by the steering logic.This mode of operation eliminates the output counting spikes normallyassociated with asynchronous (ripple-clock) counters.

The outputs of the four flip-flops are triggered on alow-to-high-level transition of either count/clock (UP or DOWN)input. The direction of the count is determined by which count inputis pulsed while the other count input is high.

All four counters are fully programmable; that is, each output maybe preset to either level by placing a low on the load () input and entering the desireddata at the data inputs. The output changes to agree with the datainputs independently of the count pulses. This feature allows thecounters to be used as modulo-N dividers by simply modifying thecount length with the preset inputs.

A high level applied to the clear (CLR) input forces all outputsto the low level. The clear function is independent of the count andi nputs. TheUP, DOWN, and inputs arebuffered to lower the drive requirement, which significantly reducesthe loading on, or current required by, clock drivers, etc., for longparallel words.

These counters are designed to be cascaded without the need forexternal circuitry. The borrow () output produces a low-level pulse while the count iszero (all Q outputs low) and the DOWN input is low. Similarily, thecarry (CO\) output produces a low-level pulse while the count is 9 or15 (all Q outputs high) and the UP input is low. The counters canthen be easily cascaded by feeding and to thecount-down and count-up inputs, respectively, of the succeedingcounter.

The SN54ALS193A is characterized for operation over the fullmilitary temperature range of -55°C to 125°C. TheSN74ALS193A is characterized for operation from 0°C to70°C.

View more information about generic part numbers:SN54ALS193A, SN74ALS193A

Go to the Engineering Design Center to locate information on other TI Semiconductor devices.

(c) Copyright 1998 Texas Instruments Incorporated. All rights reserved.
Trademarks, Important Notice!