參數(shù)資料
型號(hào)： M48T37V-10MH1E
廠商： STMICROELECTRONICS
元件分類： 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, PDSO44
封裝： 0.330 INCH, ROHS COMPLIANT, PLASTIC, SOH-44
文件頁(yè)數(shù)： 7/30頁(yè)
文件大?。?/td> 515K
代理商： M48T37V-10MH1E
M48T37Y, M48T37V
Clock operations
Doc ID 7019 Rev 9
Figure 8.
Backup mode alarm waveforms
3.5
Calibrating the clock
The M48T37Y/V is driven by a quartz controlled oscillator with a nominal frequency of
32,768 Hz. The devices are tested not to exceed ±35 ppm (parts per million) oscillator
frequency error at 25 °C, which equates to about ±1.53 minutes per month. With the
calibration bits properly set, the accuracy of each M48T37Y/V improves to better than
+1/–2 ppm at 25 °C.
The oscillation rate of any crystal changes with temperature (see Figure 10 on page 19).
Most clock chips compensate for crystal frequency and temperature shift error with
cumbersome trim capacitors. The M48T37Y/V design, however, employs periodic counter
correction. The calibration circuit adds or subtracts counts from the oscillator divider circuit
at the divide by 256 stage, as shown in Figure 11 on page 19. The number of times pulses
are blanked (subtracted, negative calibration) or split (added, positive calibration) depends
upon the value loaded into the five-bit calibration byte found in the control register. Adding
counts speeds the clock up, subtracting counts slows the clock down.
The calibration byte occupies the five lower order bits (D4-D0) in the control register 7FF8h.
These bits can be set to represent any value between 0 and 31 in binary form. Bit D5 is the
sign bit; '1' indicates positive calibration, '0' indicates negative calibration. Calibration occurs
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 (64 minutes x 60 seconds/minute x 32,768 cycles/second)
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.
AI03254B
VCC
IRQ/FT
tREC
VPFD (max)
VPFD (min)
ABE, AFE bit in Interrupt Register
AF bit in Flags Register
HIGH-Z
VSO
HIGH-Z
相關(guān)PDF資料
PDF描述
M48T37Y-70MH6 0 TIMER(S), REAL TIME CLOCK, PDSO44
M48T37Y-70MH1TR 0 TIMER(S), REAL TIME CLOCK, PDSO44
M48T37V-10MH6TR 0 TIMER(S), REAL TIME CLOCK, PDSO44
M48T513Y-70CS1 0 TIMER(S), REAL TIME CLOCK, PDSO32
M48T513Y-85CS1 0 TIMER(S), REAL TIME CLOCK, PDSO32
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
M48T37V-10MH1F 功能描述:實(shí)時(shí)時(shí)鐘 256K (32Kx8) 100ns 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(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
M48T37V-10MH1TR 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM
M48T37V-10MH6 功能描述:實(shí)時(shí)時(shí)鐘 256K (32Kx8) 100ns 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(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
M48T37V-10MH6E 功能描述:實(shí)時(shí)時(shí)鐘 256K (32Kx8) 100ns 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(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
M48T37V-10MH6F 功能描述:實(shí)時(shí)時(shí)鐘 256K (32Kx8) 100ns 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(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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