SN74AS869FN

更新时间： 2024-11-19 13:13:47

品牌	Logo	应用领域
德州仪器 - TI		计数器
页数	文件大小	规格书
17页	288K
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数据手册

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SN74AS869FN 数据手册

SN54AS867, SN54AS869

SN74ALS867A, SN74ALS869, SN74AS867, SN74AS869

SYNCHRONOUS 8-BIT UP/DOWN COUNTERS

SDAS115C – DECEMBER 1982 – REVISED JANUARY 1995

SN54AS867, SN54AS869 . . . JT PACKAGE

• Fully Programmable With Synchronous

SN74ALS867A, SN74ALS869, SN74AS867,

SN74AS869 . . . DW OR NT PACKAGE

(TOP VIEW)

Counting and Loading

• SN74ALS867A and ′AS867 Have

Asynchronous Clear; SN74ALS869 and

′AS869 Have Synchronous Clear

ENP

• Fully Independent Clock Circuit

Simplifies Use

• Ripple-Carry Output for n-Bit Cascading

• Package Options Include Plastic

Small-Outline (DW) Packages, Ceramic

Chip Carriers (FK), and Standard Plastic

(NT) and Ceramic (JT) 300-mil DIPs

ENT

GND

CLK

description

RCO

These synchronous, presettable, 8-bit up/down

counters feature internal-carry look-ahead

circuitry for cascading in high-speed counting

applications. Synchronous operation is provided

by having all flip-flops clocked simultaneously so

that the outputs change coincidentally with each

other when so instructed by the count-enable

(ENP, ENT) inputs and internal gating. This mode

of operation eliminates the output counting spikes

normally associated with asynchronous (ripple-

clock) counters. A buffered clock (CLK) input

triggers the eight flip-flops on the rising (positive-

going) edge of the clock waveform.

SN54AS867, SN54AS869 . . . FK PACKAGE

(TOP VIEW)

1 28 27 26

These counters are fully programmable; they may

be preset to any number between 0 and 255. The

load-input circuitry allows parallel loading of the

cascaded counters. Because loading is

synchronous, selecting the load mode disables

the counter and causes the outputs to agree with

the data inputs after the next clock pulse.

12 13 14 15 16 17 18

NC – No internal connection

The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without

additional gating. Two count-enable (ENP and ENT) inputs and a ripple-carry (RCO) output are instrumental

in accomplishing this function. Both ENP and ENT must be low to count. The direction of the count is determined

by the levels of the select (S0, S1) inputs as shown in the function table. ENT is fed forward to enable RCO. RCO

thus enabled produces a low-level pulse while the count is zero (all outputs low) counting down or 255 counting

up (all outputs high). This low-level overflow-carry pulse can be used to enable successive cascaded stages.

Transitions at ENP and ENT are allowed regardless of the level of CLK. All inputs are diode clamped to minimize

transmission-line effects, thereby simplifying system design.

These counters feature a fully independent clock circuit. With the exception of the asynchronous clear on the

SN74ALS867A and ′AS867, changes at S0 and S1 that modify the operating mode have no effect on the Q

outputs until clocking occurs. For the ′AS867 and ′AS869, any time ENP and/or ENT is taken high, RCO either

goes or remains high. For the SN74ALS867A and SN74ALS869, any time ENT is taken high, RCO either goes

or remains high. The function of the counter (whether enabled, disabled, loading, or counting) is dictated solely

by the conditions meeting the stable setup and hold times.

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

12 3 4 5 6 7...17

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与SN74AS869FN相关器件

型号	品牌	获取价格	描述	数据表
SN74AS869FN3	TI	获取价格	IC,COUNTER,UP/DOWN,8-BIT BINARY,AS-TTL,LDCC,28PIN,PLASTIC
SN74AS869JT	TI	获取价格	暂无描述
SN74AS869JTP4	TI	获取价格	IC,COUNTER,UP/DOWN,8-BIT BINARY,AS-TTL,DIP,24PIN,CERAMIC
SN74AS869NT	TI	获取价格	SYNCHRONOUS 8-BIT UP/DOWN COUNTERS
SN74AS869NT	ROCHESTER	获取价格	AS SERIES, SYN POSITIVE EDGE TRIGGERED 8-BIT BIDIRECTIONAL BINARY COUNTER, PDIP24, ROHS CO
SN74AS869NT-10	TI	获取价格	AS SERIES, SYN POSITIVE EDGE TRIGGERED 8-BIT BIDIRECTIONAL BINARY COUNTER, PDIP24
SN74AS869NT3	TI	获取价格	SYNCHRONOUS 8-BIT UP/DOWN COUNTERS
SN74AS869NTE4	TI	获取价格	SYNCHRONOUS 8-BIT UP/DOWN COUNTERS
SN74AS869NTP3	TI	获取价格	IC,COUNTER,UP/DOWN,8-BIT BINARY,AS-TTL,DIP,24PIN,PLASTIC
SN74AS86A	TI	获取价格	QUADRUPLE 2-INPUT EXCLUSIVE-OR GATES

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