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参数资料
| 型号： | DS17885N-3 |
| 厂商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分类： | XO, clock |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDIP24 |
| 封装： | DIP-24 |
| 文件页数： | 9/38页 |
| 文件大小： | 410K |
| 代理商： | DS17885N-3 |
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DS17885/DS17887
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can be used to determine if and how many RTC writes have occurred since the last time this register was
read.
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 4B is used to
turn the auxiliary battery on and off for the above functions in the absence of VCC. When set to a 1, VBAUX
battery power is enabled; when cleared to 0, VBAUX battery power is disabled to these functions.
In the DS17885/DS17887, this auxiliary battery can 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 that powers on the system at a predetermined
date and time through activation of the PWR output pin. In addition, the kickstart feature allows 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 can 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, 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 is not 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
4B (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 by the kickstart-interrupt-enable bit in extended control
register 4B (KSE, bank 1, 04BH).
A wake-up sequence occurs as follows: When wake-up is enabled through WIE = 1 while the system is
powered down (no VCC voltage), the clock/calendar monitors the current date for a match condition with
the date alarm register (bank 1, register 049H). 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 occurs at the date and time specified by the date, hours, minutes, and
seconds alarm register values. This additional alarm occurs regardless of the programming of the AIE bit
(bank 0, register B, 0BH). When the match condition occurs, the PWR pin is automatically driven low.
This output can be used to turn on the main system power supply that 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) is set, indicating that a wake-up condition has occurred.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS17885N-5 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:3V/5V Real-Time Clock |
| DS17885S-3 | 功能描述:实时时钟 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 |
| DS17885S-3+ | 功能描述:实时时钟 3V/5V RTC 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 |
| DS17885S-5 | 功能描述:实时时钟 3V/5V RTC 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 |
| 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 |
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