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| 型号： | M48T212V-85MH1E |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 时钟/数据恢复及定时提取 |
| 英文描述： | REAL TIME CLOCK, PDSO44 |
| 封装： | 0.330 INCH, ROHS COMPLIANT, PLASTIC, SOH-44 |
| 文件页数： | 13/35页 |
| 文件大小： | 348K |
| 代理商： | M48T212V-85MH1E |
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Clock operation
M48T212V
Figure 8.
Back-up mode alarm waveforms
3.6
Watchdog timer
The watchdog timer can be used to detect an out-of-control microprocessor. The user
programs the watchdog timer by setting the desired amount of time-out into the Watchdog
Register, address 7h.
Bits BMB4-BMB0 store a binary multiplier and the two lower-order bits RB1-RB0 select the
resolution, where 00=1/16 second, 01=1/4 second, 10=1 second, and 11=4 seconds. The
amount of time-out is then determined to be the multiplication of the five-bit multiplier value
with the resolution. (For example: writing 00001110 in the Watchdog Register = 3*1 or 3
seconds).
Note:
Accuracy of timer is within ± the selected resolution.
If the processor does not reset the timer within the specified period, the M48T212V sets the
WDF (Watchdog Flag) and generates a watchdog interrupt or a microprocessor reset. WDF
is reset by reading the Flags Register (Address 0h).
The most significant bit of the Watchdog Register is the Watchdog Steering Bit (WDS).
When set to a '0.' the watchdog will activate the IRQ/FT pin when timed-out. When WDS is
set to a '1,' the watchdog will output a negative pulse on the RST pin for 40 to 200 ms. The
Watchdog register, AFE, ABE, and FT Bits will reset to a '0' at the end of a Watchdog time-
out when the WDS Bit is set to a '1.'
The watchdog timer can be reset by two methods:
1.
a transition (high-to-low or low-to-high) can be applied to the Watchdog Input pin (WDI)
or
2.
the microprocessor can perform a WRITE of the Watchdog Register.
The time-out period then starts over. The WDI pin should be tied to VSS if not used. The
watchdog will be reset on each transition (edge) seen by the WDI pin. In the order to
AI03622
VCC
IRQ/FT
HIGH-Z
VPFD (max)
VPFD (min)
AFE Bit/ABE Bit
AF Bit in Flags Register
HIGH-Z
tREC
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| M48T35V-10MH1TR | 1 TIMER(S), REAL TIME CLOCK, PDSO28 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M48T212V-85MH1F | 功能描述:监控电路 SRAM TK 16X8 85ns RoHS:否 制造商:STMicroelectronics 监测电压数: 监测电压: 欠电压阈值: 过电压阈值: 输出类型:Active Low, Open Drain 人工复位:Resettable 监视器:No Watchdog 电池备用开关:No Backup 上电复位延迟（典型值）:10 s 电源电压-最大:5.5 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:UDFN-6 封装:Reel |
| M48T212V-85MH1TR | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER[ CONTROLLER |
| M48T212V-85MH6 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER[ CONTROLLER |
| M48T212V-85MH6E | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER CONTROLLER Supervisor |
| M48T212V-85MH6F | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5V/3.3V TIMEKEEPER CONTROLLER Supervisor |
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