參數(shù)資料
型號(hào)： M48T35Y-70MH1E
廠商： STMICROELECTRONICS
元件分類(lèi)： 時(shí)鐘/數(shù)據(jù)恢復(fù)及定時(shí)提取
英文描述： 0 TIMER(S), REAL TIME CLOCK, PDSO28
封裝： 0.330 INCH, SNAPHAT, ROHS COMPLIANT, PLASTIC, SOH-28
文件頁(yè)數(shù)： 6/30頁(yè)
文件大?。?/td> 256K
代理商： M48T35Y-70MH1E
Clock operations
M48T35 M48T35Y
within a 64 minute cycle. The first 62 minutes in the cycle may, once per minute, have one
second either shortened by 128 or lengthened by 256 oscillator cycles. If a binary '1' is
loaded into the register, only the first 2 minutes in the 64 minute cycle will be modified; if a
binary 6 is loaded, the first 12 will be affected, and so on.
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 in
fact 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 M48T35/Y may
require. The first involves simply setting the clock, letting it run for a month and comparing it
to a known accurate reference (like WWV broadcasts). While that may seem crude, it allows
the designer to give the end user the ability to calibrate his clock as his environment may
require, even after the final product is packaged in a non-user serviceable enclosure. All the
designer has to do is provide a simple utility that accesses the calibration byte.
The second approach is better suited to a manufacturing environment, and involves the use
of some test equipment. When the frequency test (FT) bit, the seventh-most significant bit in
the day register is set to a '1,' and D7 of the seconds register is a '0' (oscillator running),
DQ0 will toggle at 512 Hz during a READ of the seconds register. Any deviation from 512 Hz
indicates the degree and direction of oscillator frequency shift at the test temperature. For
example, a reading of 512.01024 Hz would indicate a +20 ppm oscillator frequency error,
requiring a –10 (WR001010) 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 FT bit MUST be reset to '0' for normal clock operations to resume. The FT bit is
automatically reset on power-down.
For more information on calibration, see application note AN934, “TIMEKEEPER
Calibration.”
3.5
Century bit
Bit D5 and D4 of clock register 1FFCh contain the CENTURY ENABLE bit (CEB) and the
CENTURY bit (CB). Setting CEB to a '1' will cause CB to toggle, either from a '0' to '1' or
from '1' to '0' at the turn of the century (depending upon its initial state). If CEB is set to a '0,'
CB will not toggle.
Note:
The WRITE bit must be set in order to write to the CENTURY bit.
相關(guān)PDF資料
PDF描述
M48T36Y-70MH1TR 0 TIMER(S), REAL TIME CLOCK, PDSO44
M48T37Y-10MH6 0 TIMER(S), REAL TIME CLOCK, PDSO44
M48T37V-70MH1TR 0 TIMER(S), REAL TIME CLOCK, PDSO44
M48T37V-70MH1 0 TIMER(S), REAL TIME CLOCK, PDSO44
M48T37Y-10MH6TR 0 TIMER(S), REAL TIME CLOCK, PDSO44
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
M48T35Y-70MH1F 功能描述:實(shí)時(shí)時(shí)鐘 256K (32Kx8) 70ns RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線(xiàn)接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)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
M48T35Y-70MH1F-CUT TAPE 制造商:ST 功能描述:M48T35Y Series 256 Kb (32 K x 8) 5.5 V 70 ns Timekeeper?SRAM - SOH-28
M48T35Y-70MH1TR 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:5V, 256 Kbit (32 Kb x 8) TIMEKEEPER SRAM
M48T35Y-70MH6 制造商:STMICROELECTRONICS 制造商全稱(chēng):STMicroelectronics 功能描述:5V, 256 Kbit (32 Kb x 8) TIMEKEEPER SRAM
M48T35Y-70MH6E 功能描述:實(shí)時(shí)時(shí)鐘 256K (32Kx8) 70ns RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線(xiàn)接口:I2C 日期格式:DW:DM:M:Y 時(shí)間格式:HH:MM:SS RTC 存儲(chǔ)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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