SN74LS297
- Digital Design Avoids Analog Compensation Errors
- Easily Cascadable for Higher Order Loops
- Useful Frequency from DC to:
- 50 MHz Typical (K Clock)
- 35 MHz Typical (I/D Clock)
The SN54LS297 and SN74LS297 devices are designed to provide a simple, cost-effective solution to high-accuracy, digital, phase-locked-loop applications. These devices contain all the necessary circuits, with the exception of the divide-by-N counter, to build first order phase-locked loops as described in Figure 1.
Both exclusive-OR (XORPD) and edge-controlled (ECPD) phase detectors are provided for maximum flexibility.
Proper partitioning of the loop function, with many of the building blocks external to the package, makes it easy for the designer to incorporate ripple cancellation or to cascade to higher order phase-locked loops.
The length of the up/down K counter is digitally programmable according to the K counter function table. With A, B, C, and D all low, the K counter is disabled. With A high and B, C, and D low, the K counter is only three stages long, which widens the bandwidth or capture range and shortens the lock time of the loop. When A, B, C, and D are all programmed high, the K counter becomes seventeen stages long, which narrows the bandwidth or capture range and lengthens the lock time. Real-time control of loop bandwidth by manipulating the A through D inputs can maximize the overall performance of the digital phase-locked loop.
The 'LS297 can perform the classic first-order phase-locked loop function without using analog components. The accuracy of the digital phase-locked loop (DPLL) is not affected by VCC and temperature variations, but depends solely on accuracies of the K clock, I/D clock, and loop propagation delays. The I/D clock frequency and the divide-by-N modulos will determine the center frequency of the DPLL. The center frequency is defined by the relationship fc = I/D Clock /2N(Hz).
技术文档
类型 | 标题 | 下载最新的英语版本 | 日期 | |||
---|---|---|---|---|---|---|
* | 数据表 | Digital Phase-Locked-Loop Filters 数据表 | 1988年 3月 1日 | |||
选择指南 | Logic Guide (Rev. AB) | 2017年 6月 12日 | ||||
应用手册 | Understanding and Interpreting Standard-Logic Data Sheets (Rev. C) | 2015年 12月 2日 | ||||
选择指南 | 逻辑器件指南 2014 (Rev. AA) | 最新英语版本 (Rev.AB) | 2014年 11月 17日 | |||
用户指南 | LOGIC Pocket Data Book (Rev. B) | 2007年 1月 16日 | ||||
应用手册 | Semiconductor Packing Material Electrostatic Discharge (ESD) Protection | 2004年 7月 8日 | ||||
应用手册 | TI IBIS File Creation, Validation, and Distribution Processes | 2002年 8月 29日 | ||||
应用手册 | 使用逻辑器件进行设计 (Rev. C) | 1997年 6月 1日 | ||||
应用手册 | Designing with the SN54/74LS123 (Rev. A) | 1997年 3月 1日 | ||||
应用手册 | Digital PLL Design Using the SN54/74LS297 (Rev. B) | 1997年 3月 1日 | ||||
应用手册 | Input and Output Characteristics of Digital Integrated Circuits | 1996年 10月 1日 | ||||
应用手册 | Live Insertion | 1996年 10月 1日 |
设计和开发
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14-24-LOGIC-EVM — 采用 14 引脚至 24 引脚 D、DB、DGV、DW、DYY、NS 和 PW 封装的逻辑产品通用评估模块
14-24-LOGIC-EVM 评估模块 (EVM) 旨在支持采用 14 引脚至 24 引脚 D、DW、DB、NS、PW、DYY 或 DGV 封装的任何逻辑器件。
封装 | 引脚 | 下载 |
---|---|---|
PDIP (N) | 16 | 查看选项 |
订购和质量
- RoHS
- REACH
- 器件标识
- 引脚镀层/焊球材料
- MSL 等级/回流焊峰值温度
- MTBF/时基故障估算
- 材料成分
- 鉴定摘要
- 持续可靠性监测
- 制造厂地点
- 封装厂地点