參數資料
型號: M41T83RM6F
廠商: STMICROELECTRONICS
元件分類: 時鐘/數據恢復及定時提取
英文描述: 1 TIMER(S), REAL TIME CLOCK, PDSO8
封裝: 0.150 INCH, ROHS COMPLIANT, PLASTIC, SOP-8
文件頁數: 33/61頁
文件大?。?/td> 983K
代理商: M41T83RM6F
M41T82-M41T83
Clock operation
Doc ID 12578 Rev 12
3.10
Battery low warning
The M41T8x automatically checks the battery each time VCC powers up and each time the
clock rolls over at midnight.
VBAT is compared to VBL (approximately 2.5 V), then the battery low (BL) bit, D4 of flags
register 0Fh, is set if the battery voltage is found to be less than VBL. Similarly, if VBAT is
greater than VBL, the BL bit is cleared during battery check.
The BL bit retains its state until the next battery check occurs. This means the BL bit will not
clear immediately upon battery replacement, but only after the next battery check occurs at
the next power-up or midnight rollover.
If a battery low is generated during a power-up sequence, this indicates that the battery is
below approximately 2.5 volts and may not be able to maintain data integrity. Clock data
should be considered suspect and verified as correct. A fresh battery should be installed.
If a battery low indication is generated during the 24-hour interval check, this indicates that
the battery is near end of life. However, data is not compromised due to the fact that a
nominal VCC is supplied. In order to ensure data integrity during subsequent periods of
battery backup mode, the battery should be replaced.
Midnight rollover check
As shown in Figure 22, during the midnight rollover check, the M41T8x applies a load to the
battery, then compares VBAT to VBL and updates the BL bit accordingly. Because a load is
present, an open condition on the VBAT pin will result in the BL bit being set. After the check
is performed, the RTC removes the load.
Power-up battery check
During the power-up check, no load is applied to the battery under the assumption the
battery has already been stressed to its working level by having powered the RTC in backup
mode. If no battery is present, VBAT will be floating and the battery check result will be
indeterminate.
Figure 22.
Battery check
V
BAT
V
BL=2.5V
Only at
rollover
BL
FF
Q
S
R
At power-up
and at rollover
RL
AM03009v1
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參數描述
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M41T83RMY6F 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: 安裝風格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube
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M41T83RQ6F 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Serial RTC with battery switchover
M41T83RQA6E 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Serial I2C bus RTC with battery switchover