SN74ALS869
- Fully Programmable With Synchronous Counting and Loading
- SN74ALS867A and ´AS867 Have Asynchronous Clear; SN74ALS869 and ´AS869 Have Synchronous Clear
- 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
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 (,) 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.
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.
The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without additional gating. Two count-enable (and ) inputs and a ripple-carry () output are instrumental in accomplishing this function. Both and 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. is fed forward to enable . 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 and 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, either goes or remains high. For the SN74ALS867A and SN74ALS869, any time is taken high, 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.
The SN54AS867 and SN54AS869 are characterized for operation over the full military temperature range of -55°C to 125°C. The SN74ALS867A, SN74ALS869, SN74AS867, and SN74AS869 are characterized for operation from 0°C to 70°C.
관심 가지실만한 유사 제품
비교 대상 장치와 유사한 기능
기술 자료
유형 | 직함 | 날짜 | ||
---|---|---|---|---|
* | Data sheet | Synchronous 8-Bit Up/Down Counters datasheet (Rev. C) | 1995/01/01 | |
Selection guide | Logic Guide (Rev. AB) | 2017/06/12 | ||
Application note | Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) | 2015/12/02 | ||
User guide | LOGIC Pocket Data Book (Rev. B) | 2007/01/16 | ||
Application note | Semiconductor Packing Material Electrostatic Discharge (ESD) Protection | 2004/07/08 | ||
Application note | TI IBIS File Creation, Validation, and Distribution Processes | 2002/08/29 | ||
Application note | Bus-Interface Devices With Output-Damping Resistors Or Reduced-Drive Outputs (Rev. A) | 1997/08/01 | ||
Application note | Designing With Logic (Rev. C) | 1997/06/01 | ||
Application note | Input and Output Characteristics of Digital Integrated Circuits | 1996/10/01 | ||
Application note | Live Insertion | 1996/10/01 | ||
Application note | Advanced Schottky (ALS and AS) Logic Families | 1995/08/01 |
설계 및 개발
추가 조건 또는 필수 리소스는 사용 가능한 경우 아래 제목을 클릭하여 세부 정보 페이지를 확인하세요.
14-24-LOGIC-EVM — 14핀~24핀 D, DB, DGV, DW, DYY, NS 및 PW 패키지용 로직 제품 일반 평가 모듈
14-24-LOGIC-EVM 평가 모듈(EVM)은 14핀~24핀 D, DW, DB, NS, PW, DYY 또는 DGV 패키지에 있는 모든 로직 장치를 지원하도록 설계되었습니다.
패키지 | 핀 | CAD 기호, 풋프린트 및 3D 모델 |
---|---|---|
SOIC (DW) | 24 | Ultra Librarian |
주문 및 품질
- RoHS
- REACH
- 디바이스 마킹
- 납 마감/볼 재질
- MSL 등급/피크 리플로우
- MTBF/FIT 예측
- 물질 성분
- 인증 요약
- 지속적인 신뢰성 모니터링
- 팹 위치
- 조립 위치