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參數(shù)資料
| 型號： | M48T212V-85MH1E |
| 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： | REAL TIME CLOCK, PDSO44 |
| 封裝： | 0.330 INCH, ROHS COMPLIANT, PLASTIC, SOH-44 |
| 文件頁數(shù)： | 15/35頁 |
| 文件大小： | 348K |
| 代理商： | M48T212V-85MH1E |
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Obsolete
Product(s)
- Obsolete
Product(s)
Clock operation
M48T212V
Figure 9.
(RSTIN1 & RSTIN2) timing waveforms
Table 9.
Reset AC characteristics
3.10
Calibrating the clock
The M48T212V 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 (see Figure 10 on page 24).
When the Calibration circuit is properly employed, accuracy improves to better than +1/–2
ppm at 25°C.
The oscillation rate of crystals changes with temperature. The M48T212V design 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 25. The
number of times pulses which are blanked (subtracted, negative calibration) or split (added,
positive calibration) depends upon the value loaded into the five Calibration bits found in the
Control Register. Adding counts speeds the clock up, subtracting counts slows the clock
down.
The Calibration bits occupy the five lower-order bits (D4-D0) in the Control Register 8h.
These bits can be set to represent any value between 0 and 31 in binary form. Bit D5 is a
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.
Symbol
Parameter(1)
1.
Valid for ambient operating temperature: TA = 0 to 70°C or –40 to 85°C; VCC = 4.5 to 5.5V or 3.0 to 3.6V
(except where noted).
Min
Max
Unit
tR1
(2)
2.
Pulse width less than 50ns will result in no RESET (for noise immunity).
RSTIN1 low to RSTIN1 high
200
ns
tR2
(3)
3.
Pulse width less than 20ms will result in no RESET (for noise immunity).
RSTIN2 low to RSTIN2 high
100
ms
tR1HRH
(4)
4.
RSTIN1 high to RST high
40
200
ms
tR2HRH
RSTIN2 high to RST high
40
200
ms
AI02642
RSTIN1
RST
RSTIN2
tR1
tR1HRH
tR2
tR2HRH
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| M48T212V-85MH1F | 功能描述:監(jiān)控電路 SRAM TK 16X8 85ns RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復(fù)位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復(fù)位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel |
| M48T212V-85MH1TR | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER[ CONTROLLER |
| M48T212V-85MH6 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER[ CONTROLLER |
| M48T212V-85MH6E | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER CONTROLLER Supervisor |
| M48T212V-85MH6F | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER CONTROLLER Supervisor |
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