欢迎访问ic37.com |
会员登录 免费注册
发布采购

78M6610LMU 参数 Datasheet PDF下载

78M6610LMU图片预览
型号: 78M6610LMU
PDF下载: 下载PDF文件 查看货源
内容描述: 电能计量处理器的负荷监测单位 [Energy Measurement Processor for Load Monitoring Units]
分类和应用: 监控
文件页数/大小: 63 页 / 1710 K
品牌: MAXIM [ MAXIM INTEGRATED PRODUCTS ]
 浏览型号78M6610LMU的Datasheet PDF文件第9页浏览型号78M6610LMU的Datasheet PDF文件第10页浏览型号78M6610LMU的Datasheet PDF文件第11页浏览型号78M6610LMU的Datasheet PDF文件第12页浏览型号78M6610LMU的Datasheet PDF文件第14页浏览型号78M6610LMU的Datasheet PDF文件第15页浏览型号78M6610LMU的Datasheet PDF文件第16页浏览型号78M6610LMU的Datasheet PDF文件第17页  
78M6610+LMU Data Sheet  
Clock Management  
The device can be clocked by either a trimmed internal RC oscillator or by oscillator circuitry that relies on  
an external crystal. The internal RC oscillator provides an accurate clock source for UART baud rate  
generation. Only time based calculations such as line frequency and watt-hour (energy) are affected by  
clock accuracy.  
The chip hardware automatically handles the clock sources logic and distributes the clock to the rest of  
the device. Upon reset or power-on, the device will utilize the internal RC oscillator circuit for the first 1024  
clock cycles, allowing the external crystal adequate time to start-up. The device will then automatically  
select the external clock, if available. It will also automatically switch back to the internal oscillator in the  
event of a failure with the external oscillator. This condition is also monitored by the processor and  
available to the user in the STATUS register.  
The 78M6610+LMU external clock circuitry requires a 20.000MHz crystal. The circuitry includes two 18pF  
ceramic capacitors. The figure below shows the typical connection of the external crystal. This oscillator is  
self biasing and therefore an external resistor should NOT be connected across the crystal.  
18pF  
XIN  
20.000MHz  
XOUT  
18pF  
78M6610+LMU  
Figure 6. Crystal Connections  
An external 20MHz system clock signal can also be utilized instead of the crystal. In this case, the  
external clock should be connected to the XOUT pin while the XIN pin should be connected to GNDD.  
Alternatively, if no external crystal or clock is utilized, the XOUT pin should be connected to GNDD and  
the XIN pin left unconnected.  
13  
Rev 0