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参数资料
| 型号： | DS17885E-3+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 11/31页 |
| 文件大小： | 0K |
| 描述： | IC RTC 3V 8K NV RAM 28-TSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 234 |
| 类型： | 时钟/日历 |
| 特点： | 警报器，夏令时，闰年，NVSRAM，方波输出 |
| 存储容量： | 8KB |
| 时间格式： | HH:MM:SS（12/24 小时） |
| 数据格式： | YY-MM-DD-dd |
| 接口： | 并联 |
| 电源电压： | 2.7 V ~ 3.7 V |
| 电压 - 电源，电池： | 2.5 V ~ 3.7 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-TSSOP（0.465"，11.8mm 宽） |
| 供应商设备封装： | 28-TSOP |
| 包装： | 托盘 |
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Periodic Interrupt Selection
The periodic interrupt causes the IRQ pin to go to an
active state from once every 500ms to once every
122s. This function is separate from the alarm inter-
rupt, which can be output from once per second to
once per day. The periodic interrupt rate is selected
using the same Register A bits that select the square-
wave frequency (see Table 4). Changing the Register A
bits affects both the square-wave frequency and the
periodic interrupt output. However, each function has a
separate enable bit in Register B. The SQWE and E32k
bits control the square-wave output. Similarly, the peri-
odic interrupt is enabled by the PIE bit in Register B.
The periodic interrupt can be used with software coun-
ters to measure inputs, create output intervals, or await
the next needed software function.
Update Cycle
The DS17x85 executes an update cycle once per sec-
ond regardless of the SET bit in Register B. When the
SET bit in Register B is set to 1, the user copy of the
double-buffered time, calendar, and alarm bytes is
frozen and does not update as the time increments.
However, the time countdown chain continues to
update the internal copy of the buffer. This feature
allows time to maintain accuracy independent of read-
ing or writing the time, calendar, and alarm buffers, and
also guarantees that time and calendar information is
consistent. The update cycle also compares each
alarm byte with the corresponding time byte and issues
an alarm if a match or if a don’t care code is present in
all alarm locations.
There are three methods that can handle access of the
RTC that avoid any possibility of accessing inconsistent
time and calendar data. The first method uses the
update-ended interrupt. If enabled, an interrupt occurs
after every update cycle that indicates that over 999ms
are available to read valid time and date information. If
this interrupt is used, the IRQF bit in Register C should
be cleared before leaving the interrupt routine.
A second method uses the update-in-progress (UIP) bit
in Register A to determine if the update cycle is in
progress. The UIP bit pulses once per second. After
the UIP bit goes high, the update transfer occurs 244s
later. If a low is read on the UIP bit, the user has at least
244s before the time/calendar data is changed.
Therefore, the user should avoid interrupt service rou-
tines that would cause the time needed to read valid
time/calendar data to exceed 244s.
The third method uses a periodic interrupt to determine
if an update cycle is in progress. The UIP bit in Register
A is set high between the setting of the PF bit in
Register C (see Figure 4). Periodic interrupts that occur
at a rate of greater than tBUC allow valid time and date
information to be reached at each occurrence of the
periodic interrupt. The reads should be complete within
1 (tPI/2 + tBUC) to ensure that data is not read during
the update cycle.
DS17285/DS17287/DS17485/DS17487/DS17885/DS17887
Real-Time Clocks
____________________________________________________________________
19
UIP
UF
PF
tBUC = DELAY TIME BEFORE UPDATE CYCLE = 244
μs.
1 SECOND
t PI
tPI/2
tBUC
Figure 4. UIP and Periodic Interrupt Timing
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS17885E-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 |
| DS17885E3+W | 制造商:Maxim Integrated Products 功能描述:3 VOLT RTC 8K RAM TSOP WAIVER PBFRE - Rail/Tube |
| DS17885E3-W | 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 |
| DS17885E5 | 制造商:MAXIM 制造商全称:Maxim Integrated Products 功能描述:Real-Time Clocks |
| DS17885E-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 |
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