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参数资料
| 型号： | M41T94MQ6E |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 时钟/数据恢复及定时提取 |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDSO16 |
| 封装： | ROHS COMPLIANT, PLASTIC, SOIC-16 |
| 文件页数： | 17/41页 |
| 文件大小： | 352K |
| 代理商： | M41T94MQ6E |
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Clock operations
M41T94
Therefore, each calibration step has the effect of adding 512 or subtracting 256 oscillator
cycles for every 125,829,120 actual oscillator cycles, that is +4.068 or –2.034 ppm of
adjustment per calibration step in the calibration register. Assuming that the oscillator is
running at exactly 32,768 Hz, each of the 31 increments in the calibration byte would
represent +10.7 or –5.35 seconds per month which corresponds to a total range of +5.5 or
–2.75 minutes per month.
Two methods are available for ascertaining how much calibration a given M41T94 may
require.
The first involves setting the clock, letting it run for a month and comparing it to a known
accurate reference and recording deviation over a fixed period of time. Calibration values,
including the number of seconds lost or gained in a given period, can be found in application
note AN934: TIMEKEEPER calibration. This allows the designer to give the end user the
ability to calibrate the clock as the environment requires, even if the final product is
packaged in a non-user serviceable enclosure. The designer could provide a simple utility
that accesses the calibration byte.
The second approach is better suited to a manufacturing environment, and involves the use
of the IRQ/FT/OUT pin. The pin will toggle at 512 Hz, when the stop bit (ST, D7 of 1h) is '0,'
the frequency test bit (FT, D6 of 8h) is '1,' the alarm flag enable bit (AFE, D7 of Ah) is '0,' and
the watchdog steering bit (WDS, D7 of 9h) is '1' or the watchdog register (9h = 0) is reset.
Any deviation from 512 Hz indicates the degree and direction of oscillator frequency shift at
the test temperature. For example, a reading of 512.010124 Hz would indicate a +20 ppm
oscillator frequency error, requiring a –10 (XX001010) to be loaded into the calibration byte
for correction.
Note:
Setting or changing the calibration byte does not affect the frequency test output frequency.
The IRQ/FT/OUT pin is an open drain output which requires a pull-up resistor for proper
operation. A 500 to 10 k
Ω resistor is recommended in order to control the rise time. The FT
bit is cleared on power-down.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M41T94MQ6F | 功能描述:实时时钟 Serial 512 (64x8) RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| M41T94MQ6TR | 功能描述:实时时钟 Advanced Analog RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| M41T94SH | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:512 Bit 64 bit x8 SERIAL RTC SPI SRAM |
| M41TC8025 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:Highly accurate, temperature-compensated serial real-time clock (RTC) with embedded crystal |
| M41TC8025AMC6F | 制造商:STMicroelectronics 功能描述:Real Time Clock Serial 14-Pin SOIC T/R 制造商:STMicroelectronics 功能描述:HIGH-END SENSOR AND ANALOG - Tape and Reel 制造商:STMicroelectronics 功能描述:HIGH-END SENSOR and ANALOG |
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