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參數(shù)資料
| 型號： | DS17885S-5 |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Timer or RTC |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDSO24 |
| 封裝： | SOIC-24 |
| 文件頁數(shù)： | 9/38頁 |
| 文件大?。?/td> | 407K |
| 代理商： | DS17885S-5 |
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DS17885/DS17887
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AUXILIARY BATTERY
The VBAUX input is provided to supply power from an auxiliary battery for the DS17885/DS17887
kickstart, wake-up, and SQW output features in the absence of VCC. This power source must be available
in order to use these auxiliary features when no VCC is applied to the device.
The Auxiliary Battery Enable (ABE; bank 1, register 04BH) bit in extended control register B is used to
turn on and off the auxiliary battery for the above functions in the absence of VCC. When set to a 1,
VBAUX battery power is enabled, and when cleared to 0, VBAUX battery power is disabled to these
functions.
In the DS17885/DS17887, this auxiliary battery may be used as the primary backup power source for
maintaining the clock/calendar, user RAM, and extended external RAM functions. This occurs if the
VBAT pin is at a lower voltage than VBAUX. If the DS17885 is to be backed-up using a single battery with
the auxiliary features enabled, then VBAUX should be used and VBAT should be grounded. If VBAUX is not
to be used, it should be grounded and ABE should be cleared to 0.
WAKE-UP/KICKSTART
The DS17885/DS17887 incorporates a wake-up feature which can power the system on at a
predetermined date and time through activation of the PWR output pin. In addition, the kickstart feature
can allow the system to be powered up in response to a low going transition on the KS pin, without
operating voltage applied to the VCC pin. As a result, system power may be applied upon such events as a
key closure, or modem ring detect signal. In order to use either the wake-up or the kickstart features, the
DS17885/DS17887 must have an auxiliary battery connected to the VBAUX pin and the oscillator must be
running and the countdown chain must not be in reset (Register A DV2, DV1, DV0 = 01X). If DV2,
DV1, and DV0 are not in this required state, the PWR pin will not be driven low in response to a kickstart
or wake-up condition, while in battery-backed mode.
The wake-up feature is controlled through the Wake-up Interrupt Enable bit in extended control register B
(WIE, bank 1, 04BH). Setting WIE to 1 enables the wake-up feature, clearing WIE to 0 disables it.
Similarly, the kickstart feature is controlled through the Kickstart Interrupt Enable bit in extended control
register B (KSE, bank 1, 04BH).
A wake-up sequence will occur as follows: When wake-up is enabled via WIE = 1 while the system is
powered down (no VCC voltage), the clock/calendar will monitor the current date for a match condition
with the date alarm register (bank 1, register 049H). In conjunction with the date alarm register, the
hours, minutes, and seconds alarm bytes in the clock/calendar register map (bank 0, registers 05H, 03H,
and 01H) are also monitored. As a result, a wake-up will occur at the date and time specified by the date,
hours, minutes, and seconds alarm register values. This additional alarm will occur regardless of the
programming of the AIE bit (bank 0, register B, 0BH). When the match condition occurs, the PWR pin
will automatically be driven low. This output can be used to turn on the main system power supply
which provides VCC voltage to the DS17885/DS17887 as well as the other major components in the
system. Also at this time, the Wake-Up flag (WF, bank 1, register 04AH) will be set, indicating that a
wake-up condition has occurred.
A kickstart sequence will occur when kickstarting is enabled via KSE = 1. While the system is powered
down, the KS input pin will be monitored for a low going transition of minimum pulse width tKSPW.
When such a transition is detected, the PWR line will be pulled low, as it is for a wake-up condition.
相關(guān)PDF資料 |
PDF描述 |
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| DS17885E-5 | 1 TIMER(S), REAL TIME CLOCK, PDSO28 |
| DS1821+ | DIGITAL TEMP SENSOR-SERIAL, 8BIT(s), 1Cel, RECTANGULAR, SURFACE MOUNT |
| DS1821S+ | DIGITAL TEMP SENSOR-SERIAL, 8BIT(s), 1Cel, RECTANGULAR, SURFACE MOUNT |
| DS1821S | DIGITAL TEMP SENSOR-SERIAL, 8BIT(s), 1Cel, RECTANGULAR, SURFACE MOUNT |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS17885S-5/T&R+ | 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK MULTIPLEXED 8KBYTE 24SOIC - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC RTC 5V 8K NV RAM 24-SOIC |
| DS17885S-5/T&R | 功能描述:實(shí)時(shí)時(shí)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(shí)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(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS17885S-5/T&R+ | 功能描述:實(shí)時(shí)時(shí)鐘 3V/5V 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(shí)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(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS17885S-5+ | 功能描述:實(shí)時(shí)時(shí)鐘 3V/5V 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(shí)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(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS17885SN-3 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock |
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