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參數(shù)資料
| 型號： | MAX6917EO30 |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 時鐘/數(shù)據(jù)恢復及定時提取 |
| 英文描述： | REAL TIME CLOCK, PDSO20 |
| 封裝： | 0.150 INCH, 0.025 INCH PITCH, MO-137AD, QSOP-20 |
| 文件頁數(shù)： | 19/31頁 |
| 文件大小： | 349K |
| 代理商： | MAX6917EO30 |
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MAX6917
I2C-Compatible RTC with Microprocessor
Supervisor, Alarm, and NV RAM Controller
26
______________________________________________________________________________________
Battery Test
Battery-Test Normal Operation
In normal operation, the battery-test circuitry uses the
control register POR settings of INT/EXT TEST, which is
set to logic low as default (Table 1). In this mode, all bat-
tery-test load resistors and threshold settings are internal.
When VCC rises above VRST, the MAX6917 automatically
performs one power-on battery monitor test. Additionally,
a battery check is performed every time that a reset is
issued, either from a manual reset or a watchdog timeout.
After that, periodic battery voltage monitoring at the facto-
ry-programmed time interval of 24hr begins while VCC is
applied.
After each 24hr period (tBTCN) has elapsed, the
MAX6917 connects VBATT to an internal 0.91M
(typ)
test resistor (RSET+_Int + RSET-_Int) for 1s (tBTPW)
(Figure 17). During this 1s, if VBATT falls below the fac-
tory-programmed battery trip point VBTP, the open-
drain, battery-low output, BATT_LO, is asserted active
low and the BATT LO bit in the status register is set to
one. The BATT LO output can be register selected to
toggle at a 1Hz rate (0.5s on, 0.5s off) when active.
Once BATT LO is active, the 24hr tests stop until a
fresh battery is inserted and BATT LO is cleared by
writing any data to the battery test register at address
0x0D (Figure 18). Writing to this register performs a
battery test and provided that the fresh battery is not
low, deactivates the BATT LO output and resets BATT
LO in the status register. Normal 24hr testing resumes.
If a different load or BATT LO thresholds are desired for
testing the backup battery, then external program resis-
tors can be used in conjunction with the TRIP and TEST
inputs (see the Battery Test-Control Register and Other
Test Options section).
Battery replacement following BATT_LO activation
should be done with VCC nominal and not in battery-
backup mode so that SRAM data is not lost.
Alternatively, if SRAM data need not be saved, the bat-
tery can be replaced with the VCC supply removed. If a
battery is replaced in battery-backup mode, sufficient
time must be allowed for the voltage on the VOUT out-
put to decay to zero. This ensures that the freshness-
seal mode of operation has been reset and is active
when VCC is powered up again. If insufficient time is
allowed, then VCC must exceed VBATT during the sub-
sequent power-up to ensure that the MAX6917 has left
battery-backup mode (Figure 19).
The MAX6917 does not constantly monitor an attached
battery because such monitoring would drastically
reduce the life of the battery. As a result, the MAX6917
MAX6917
1.24V
VCC
BATT_LO
CONTROL
LOGIC
RSET+_INT
480k
RSET-_INT
430k
VOUT
INT/EXT
TEST = 0
(
±5mA)
BATT
TEST
TRIP
VBATT
BATT_LO
RSET+_EXT
RLOAD_EXT
(OPTIONAL)
RSET-_EXT
QEXT
INT/EXT
TEST
Figure 17. MAX6917 Battery Load and Test Circuit
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| MAX6917EO30+ | 功能描述:實時時鐘 Integrated Circuits (ICs) 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 |
| MAX6917EO30+T | 功能描述:實時時鐘 Integrated Circuits (ICs) 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 |
| MAX6917EO33+ | 功能描述:實時時鐘 Integrated Circuits (ICs) 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 |
| MAX6917EO33+T | 功能描述:實時時鐘 Integrated Circuits (ICs) 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 |
| MAX6917EO50 | 功能描述:實時時鐘 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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