LMH1982
目录
概述.............................................................................................................................. 1
产品特点.............................................................................................................................................. 1
应用......................................................................................................................................... 1
典型的系统框图............................................................................................................... 1
功能框图...................................................................................................................... 2
订购信息............................................................................................................................. 2
连接图............................................................................................................................. 3
绝对最大额定值.................................................................................................................... 6
工作额定值................................................................................................................................ 6
电气特性........................................................................................................................ 6
典型性能特征....................................................................................................... 8
应用信息.......................................................................................................................... 9
1.0功能概述............................................................................................................. 9
2.0一般编程信息.............................................. ..................................... 9
2.1推荐启动编程序列........................................... ................................. 9
2.2启用同步锁相模式............................................................................................................... 9
2.3输出干扰而调整模式启用........................................... .............................. 9
操作3.0模式............................................................................................................. 10
3.1自由运行模式......................................................................................................................... 10
3.2同步锁相模式........................................................................................................................... 10
3.2.1同步锁相模式状态图........................................... .................................................. .... 10
3.2.2损失范围（ LOR ） ..................................................................................................... 10
LOR期间3.2.2.1自由运行..................................................................................................... 10
LOR期间3.2.2.2缓缴...................................................................................................... 10
3.3识别视频定时格式和标准........................................... .............................. 11
4.0输入参考................................................................................................................... 13
4.1编程VCXO的PLL分频器............................................ ............................................. 13
4.2内部参考帧解码器............................................. ................................................. 13
5.0输出时钟和TOF ....................................................................................................... 13
5.1编程输出时钟频率............................................ .................................... 13
5.2编程输出时序格式............................................ .......................................... 14
5.2.1输出时钟参考......................................................................................................... 14
5.2.2输出帧速率............................................................................................................... 14
5.2.3基准帧速率.......................................................................................................... 14
5.2.4输入输出帧率比......................................... .................................................. .... 14
5.2.5输出帧线偏移....................................................................................................... 14
5.3编程的输出排列顺序............................................ ................................. 15
5.3.1输出时钟对齐无TOF .......................................... ............................................. 15
5.4输出行为一旦亏损参考........................................... ......................................... 15
6.0参考和PLL锁定状态............................................ ............................................. 16
6.1参考检测.................................................................................................................. 16
6.1.1编程参考（ LOR ）阈值的损失...................................... ......................... 16
6.2 PLL锁定检测................................................................................................................... 16
6.2.1编程PLL锁定阈值.......................................... ........................................... 16
6.2.2 PLL锁定状态不稳定..................................................................................................... 17
7.0 VCXO的PLL环路响应............................................. .................................................. ..... 17
7.1环路响应设计.............................................方程.................................................. 17
7.1.1环路响应优化技巧........................................... ................................................ 17
7.2锁定时间的思考.......................................................................................................... 18
7.3 VCXO注意事项................................................................................................................ 18
7.4自由运行输出抖动................................................................................................................ 18
8.0 I
2
C接口协议....................................................................................................... 18
8.1写序........................................................................................................................ 18
8.2读序列........................................................................................................................ 18
8.3 I
2
C使能控制引脚.............................................................................................................. 19
9.0 I
2
C接口控制寄存器定义............................................. ...................... 19
9.1与同步锁相基准输入控制寄存器........................................... ................................. 20
9.2同步锁相状态并锁定控制寄存器........................................... ......................................... 20
9.3输入控制寄存器................................................................................................................ 20
9.4 1 PLL分频寄存器............................................................................................................... 21
9.5 4 PLL电荷泵电流控制寄存器.......................................... .................................... 21
9.6输出时钟和TOF控制寄存器........................................... ............................................ 21
9.7 TOF配置寄存器....................................................................................................... 21
9.8 1 PLL电荷泵电流控制寄存器.......................................... ..................................... 22
www.national.com
4
QQ：2880707522 复制
