參數(shù)資料
型號： M41T83SQA6E
廠商： STMICROELECTRONICS
元件分類： 時鐘/數(shù)據(jù)恢復(fù)及定時提取
英文描述： 1 TIMER(S), REAL TIME CLOCK, QCC16
封裝： 4 X 4 MM, ROHS COMPLIANT, QFN-16
文件頁數(shù)： 22/61頁
文件大?。?/td> 983K
代理商： M41T83SQA6E
M41T82-M41T83
Clock operation
Doc ID 12578 Rev 12
3.4.2
Analog calibration (programmable load capacitance)
A second method of calibration employs the use of programmable internal load capacitors to
adjust (or trim) the oscillator frequency. As discussed in Section 3.4.1, the 512 Hz frequency
test output can be used to determine the amount of frequency error in the oscillator.
Changes in the analog calibration value will affect the frequency test output, thus the user
can immediately see the effects of these changes (see Section 3.14 on page 41 for more
information on enabling the FT output).
By design, the oscillator is intended to be 0 ppm ± crystal accuracy at room temperature
(25 °C, see Figure 17 on page 30). For a 12.5 pF crystal, the default loading on each side of
the crystal will be 25 pF. For incrementing or decrementing the calibration value,
capacitance will be added or removed in increments of 0.25 pF to each side of the crystal.
Internally, CLOAD of the oscillator is changed via two digitally controlled capacitors, CXI and
CXO, connected from the XI and XO pins to ground (see Figure 16 on page 25). The
effective on-chip series load capacitance, CLOAD, ranges from 3.5 pF to 17.4 pF, with a
nominal value of 12.5 pF (AC0 – AC6 = 0).
The effective series load capacitance (CLOAD) is the combination of CXI and CXO:
Seven analog calibration bits, AC0 to AC6, are provided in order to adjust the on-chip load
capacitance value for frequency compensation of the RTC. Each bit has a different weight
for capacitance adjustment. An analog calibration sign (ACS) bit determines if capacitance
is added (ACS bit = 0, negative calibration) or removed (ACS bit = 1, positive calibration).
The majority of the calibration adjustment is positive (i.e. to increase the oscillator frequency
by removing capacitance) due to the typical characteristic of quartz crystals to slow down
due to changes in temperature, but negative calibration is also available.
Since the analog calibration register adjustment is essentially pulling the frequency of the
oscillator, the resulting frequency changes will not be linear with incremental capacitance
changes. The equations which govern this mechanism indicate that smaller capacitor values
of analog calibration adjustment will provide larger increments. Thus, the larger values of
analog calibration adjustment will produce smaller incremental frequency changes. These
values typically vary from 6-10 ppm/bit at the low end to <1 ppm/bit at the highest
capacitance settings. The range provided by the analog calibration register adjustment with
a typical surface mount crystal is approximately ±30 ppm around the AC6-AC0 = 0 default
setting because of this property (see Table 7 on page 30).
Pre-programmed calibration value
Users of the M41T83 in the embedded crystal package have the option of using the factory
programmed analog calibration value (refer to Section 3.17: OTP bit operation (M41T83 in
C
LOAD
11 C
XI
1C
XO
+
()
=
相關(guān)PDF資料
PDF描述
M41T83SQA6F 1 TIMER(S), REAL TIME CLOCK, QCC16
M41T83RQA6F 1 TIMER(S), REAL TIME CLOCK, QCC16
M41T83SMY6F 1 TIMER(S), REAL TIME CLOCK, PDSO18
M41T93ZMY6F 1 TIMER(S), REAL TIME CLOCK, PDSO18
M41T93ZQA6F 1 TIMER(S), REAL TIME CLOCK, PQCC16
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
M41T83SQA6F 功能描述:實時時鐘 Serial I2C bus RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
M41T83ZM6E 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Serial RTC with battery switchover
M41T83ZM6F 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Serial RTC with battery switchover
M41T83ZMY6E 功能描述:實時時鐘 Serial I2C bus RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
M41T83ZMY6F 功能描述:實時時鐘 Serial I2C bus RTC RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
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