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参数资料
| 型号： | M41ST85YMH6F |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 时钟/数据恢复及定时提取 |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDSO28 |
| 封装： | 0.330 INCH, SNAPHAT, LEAD FREE, PLASTIC, SOH-28 |
| 文件页数： | 14/34页 |
| 文件大小： | 532K |
| 代理商： | M41ST85YMH6F |
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M41ST85Y, M41ST85W
Power-fail INPUT/OUTPUT
The Power-Fail Input (PFI) is compared to an in-
ternal reference voltage (1.25V). If PFI is less than
the power-fail threshold (VPFI), the Power-Fail
Output (PFO) will go low. This function is intended
for use as an undervoltage detector to signal a fail-
ing power supply. Typically PFI is connected
through an external voltage divider (see Figure
7., page 7) to either the unregulated DC input (if it
is available) or the regulated output of the VCC reg-
ulator. The voltage divider can be set up such that
the voltage at PFI falls below VPFI several millisec-
onds before the regulated VCC input to the
M41ST85Y/W or the microprocessor drops below
the minimum operating voltage.
During battery back-up, the power-fail comparator
turns off and PFO goes (or remains) low. This oc-
curs after VCC drops below VPFD(min). When pow-
er returns, PFO is forced high, irrespective of VPFI
for the write protect time (trec), which is the time
from VPFD(max) until the inputs are recognized. At
the end of this time, the power-fail comparator is
enabled and PFO follows PFI. If the comparator is
unused, PFI should be connected to VSS and PFO
left unconnected.
Century Bit
Bits D7 and D6 of Clock Register 03h contain the
CENTURY ENABLE Bit (CEB) and the CENTURY
Bit (CB). Setting CEB to a '1' will cause CB to tog-
gle, 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.
Output Driver Pin
When the FT Bit, AFE Bit and watchdog register
are not set, the IRQ/FT/OUT pin becomes an out-
put driver that reflects the contents of D7 of the
Control Register. In other words, when D7 (OUT
Bit) and D6 (FT Bit) of address location 08h are a
'0,' then the IRQ/FT/OUT pin will be driven low.
Note: The IRQ/FT/OUT pin is an open drain which
requires an external pull-up resistor.
Battery Low Warning
The M41ST85Y/W automatically performs battery
voltage monitoring upon power-up and at factory-
programmed time intervals of approximately 24
hours. The Battery Low (BL) Bit, Bit D4 of Flags
Register 0Fh, will be asserted if the battery voltage
is found to be less than approximately 2.5V. The
BL Bit will remain asserted until completion of bat-
tery replacement and subsequent battery low
monitoring tests, either during the next power-up
sequence or the next scheduled 24-hour interval.
If a battery low is generated during a power-up se-
quence, this indicates that the battery is below ap-
proximately 2.5 volts and may not be able to
maintain data integrity in the SRAM. 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 bat-
tery is near end of life. However, data is not com-
promised due to the fact that a nominal VCC is
supplied. In order to insure data integrity during
subsequent periods of battery back-up mode, the
battery should be replaced. The SNAPHAT top
may be replaced while VCC is applied to the de-
vice.
Note: This will cause the clock to lose time during
the interval the SNAPHAT battery/crystal top is
disconnected.
The M41ST85Y/W only monitors the battery when
a nominal VCC is applied to the device. Thus appli-
cations which require extensive durations in the
battery back-up mode should be powered-up peri-
odically (at least once every few months) in order
for this technique to be beneficial. Additionally, if a
battery low is indicated, data integrity should be
verified upon power-up via a checksum or other
technique.
相关PDF资料 |
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| M41ST85YMH6E | 1 TIMER(S), REAL TIME CLOCK, PDSO28 |
| M41T11MH6 | 0 TIMER(S), REAL TIME CLOCK, PDSO28 |
| M41T11M6 | 0 TIMER(S), REAL TIME CLOCK, PDSO8 |
| M41T11MH6TR | 0 TIMER(S), REAL TIME CLOCK, PDSO28 |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M41ST85YMH6TR | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0 OR 3.0V, 512 bit 64 x 8 SERIAL RTC and NVRAM SUPERVISOR |
| M41ST85YMX | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0 OR 3.0V, 512 bit 64 x 8 SERIAL RTC and NVRAM SUPERVISOR |
| M41ST85YMX6 | 功能描述:实时时钟 Serial 512 (64x8) RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
| M41ST85YMX6TR | 制造商:STMicroelectronics 功能描述:REAL TIME CLOCK SERL 64BYTE 28PIN SOX - Tape and Reel |
| M41ST85YSH | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0 OR 3.0V, 512 bit 64 x 8 SERIAL RTC and NVRAM SUPERVISOR |
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