收藏本站
71M6513/71M6513H
A Maxim Integrated Products Brand
3 -Phase      Energy Meter IC
DATA SHEET
AUGUST 2011
Temperature Compensation and Mains Frequency Stabilization for the RTC
The accuracy of the RTC depends on the stability of the external crystal. Crystals vary in terms of initial accuracy as well as in
terms of behavior over temperature. The flexibility provided by the MPU allows for compensation of the RTC using the sub-
strate temperature. To achieve this, the crystal has to be characterized over temperature and the three coefficients Y_CAL ,
Y_CALC , and Y_CAL_C2 have to be calculated. Provided the IC substrate temperatures tracks the crystal temperature, the
coefficients can be used in the MPU firmware to trigger occasional corrections of the RTC seconds count, using the
RTC_DEC_SEC or RTC_INC_SEC registers in I/O RAM.
It is not recommended to measure crystal frequency directly due to the error introduced by the measurement probes. A
practical method to measure the crystal frequency (when installed on the PCB with the 71M6513) is to have a DIO pin toggle
every second, based on the RTC interrupt, with all other interrupts disabled. When this signal is measured with a precision
timer, the crystal frequency can be obtained from the measured time period t (in μs):
f = 32768
10 6 μs
t
Example: Let us assume a crystal characterized by the measurements shown in Table 61. The values show that even at
nominal temperature (the temperature at which the chip was calibrated for energy), the deviation from the ideal crystal
frequency is 11.6 PPM, resulting in about one second inaccuracy per day, i.e. more than some standards allow.
Deviation from
Nominal
Temperature [°C]
+50
+25
0
-25
-50
Measured
Frequency [Hz]
32767.98
32768.28
32768.38
32768.08
32767.58
Deviation from
Nominal
Frequency [PPM]
-0.61
8.545
11.597
2.441
-12.817
Table 61: Frequency over Temperature
As Figure 29 shows, even a constant compensation would not bring much improvement, since the temperature characteristics
of the crystal are a mix of constant, linear, and quadratic effects (in commercially available crystals, the constant and quadratic
effects are dominant).
32768.5
32768.4
32768.3
32768.2
32768.1
32768
32767.9
32767.8
32767.7
32767.6
32767.5
-50
-25
0
25
50
Figure 29: Crystal Frequency over Temperature
The temperature characteristics of the crystal are obtained from the curve in Figure 29 by curve-fitting the PPM deviations. A
fairly close curve fit is achieved with the coefficients a = 10.89, b = 0.122, and c = –0.00714 (see Figure 30).
Page: 80 of 104
? 2005-2011 Teridian Semiconductor Corporation
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
71M6515H-IGT/F IC ENERGY METER AFE 3PH 64-LQFP
71M6521BE-IGTR/F IC ENERGY METER 8K FLASH 64-LQFP
71M6533G-IGTR/F IC ENERGY METER 3PH 100LQFP
71M6543F-IGT/F IC ENERGY METERING
71M6545-IGT/F IC ENERGY METERING
720-10007-00300 CBL D-SUB 9PIN FMAL-25PIN FML 3M
720-10010-00025 CBL DSUB 9PIN FML-25PIN MAL .25M
720-10020-00300 CBL DSUB 9PIN FML-9PIN MALE 3M
相关代理商/技术参数
71M6513H-IGTR/F 功能描述:计量片上系统 - SoC 3-Phase Energy Meter I/C RoHS:否 制造商:Maxim Integrated 核心:80515 MPU 处理器系列:71M6511 类型:Metering SoC 最大时钟频率:70 Hz 程序存储器大小:64 KB 数据 RAM 大小:7 KB 接口类型:UART 可编程输入/输出端数量:12 片上 ADC: 安装风格:SMD/SMT 封装 / 箱体:LQFP-64 封装:Reel
71M6513H-IGTR/F1 功能描述:计量片上系统 - SoC RoHS:否 制造商:Maxim Integrated 核心:80515 MPU 处理器系列:71M6511 类型:Metering SoC 最大时钟频率:70 Hz 程序存储器大小:64 KB 数据 RAM 大小:7 KB 接口类型:UART 可编程输入/输出端数量:12 片上 ADC: 安装风格:SMD/SMT 封装 / 箱体:LQFP-64 封装:Reel
71M6513-IEL 制造商:未知厂家 制造商全称:未知厂家 功能描述:71M6513
71M6513-IEL/F 功能描述:计量片上系统 - SoC 3-Phase Energy Meter I/C RoHS:否 制造商:Maxim Integrated 核心:80515 MPU 处理器系列:71M6511 类型:Metering SoC 最大时钟频率:70 Hz 程序存储器大小:64 KB 数据 RAM 大小:7 KB 接口类型:UART 可编程输入/输出端数量:12 片上 ADC: 安装风格:SMD/SMT 封装 / 箱体:LQFP-64 封装:Reel
71M6513-IELR/F 制造商:Maxim Integrated Products 功能描述:Metering Systems on a Chip - SoC 3-Phase Energy Meter I/C
71M6513-IGT/F 功能描述:计量片上系统 - SoC 3-Phase Energy Meter I/C RoHS:否 制造商:Maxim Integrated 核心:80515 MPU 处理器系列:71M6511 类型:Metering SoC 最大时钟频率:70 Hz 程序存储器大小:64 KB 数据 RAM 大小:7 KB 接口类型:UART 可编程输入/输出端数量:12 片上 ADC: 安装风格:SMD/SMT 封装 / 箱体:LQFP-64 封装:Reel
71M6513-IGT/F1 功能描述:计量片上系统 - SoC RoHS:否 制造商:Maxim Integrated 核心:80515 MPU 处理器系列:71M6511 类型:Metering SoC 最大时钟频率:70 Hz 程序存储器大小:64 KB 数据 RAM 大小:7 KB 接口类型:UART 可编程输入/输出端数量:12 片上 ADC: 安装风格:SMD/SMT 封装 / 箱体:LQFP-64 封装:Reel
71M6513-IGTR/F 功能描述:计量片上系统 - SoC 3-Phase Energy Meter I/C RoHS:否 制造商:Maxim Integrated 核心:80515 MPU 处理器系列:71M6511 类型:Metering SoC 最大时钟频率:70 Hz 程序存储器大小:64 KB 数据 RAM 大小:7 KB 接口类型:UART 可编程输入/输出端数量:12 片上 ADC: 安装风格:SMD/SMT 封装 / 箱体:LQFP-64 封装:Reel