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| 型号： | DS12887A |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 3/22页 |
| 文件大小： | 0K |
| 描述： | IC RTC W/RAM 128 BYTE 24-EDIP |
| 标准包装： | 14 |
| 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： | 114B |
| 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： | 4.5 V ~ 5.5 V |
| 电压 - 电源，电池： | 2.5 V ~ 4 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 通孔 |
| 封装/外壳： | 24-DIP 模块（0.600"，15.24mm） |
| 供应商设备封装： | 24-EDIP |
| 包装： | 管件 |
DS12885/DS12887/DS12887A/DS12C887/DS12C887A
Real-Time Clocks
____________________________________________________________________
11
Detailed Description
The DS12885 family of RTCs provide 14 bytes of real-
time clock/calendar, alarm, and control/status registers
and 114 bytes (113 bytes for DS12C887 and
DS12C887A) of nonvolatile, battery-backed static RAM.
A time-of-day alarm, three maskable interrupts with a
common interrupt output, and a programmable square-
wave output are available. The devices also operate in
either 24-hour or 12-hour format with an AM/PM indica-
tor. A precision temperature-compensated circuit moni-
tors the status of VCC. If a primary power-supply failure
is detected, the devices automatically switch to a back-
up supply. The backup supply input supports a primary
battery, such as lithium coin cell. The devices are
accessed through a multiplexed address/data bus that
supports Intel and Motorola modes.
Oscillator Circuit
The DS12885 uses an external 32.768kHz crystal. The
oscillator circuit does not require any external resistors
or capacitors to operate. Table 1 specifies several crys-
tal parameters for the external crystal. Figure 1 shows a
functional schematic of the oscillator circuit. An enable
bit in the control register controls the oscillator.
Oscillator startup times are highly dependent upon
crystal characteristics, PC board leakage, and layout.
High ESR and excessive capacitive loads are the major
contributors to long startup times. A circuit using a
crystal with the recommended characteristics and
proper layout usually starts within one second.
An external 32.768kHz oscillator can also drive the
DS12885. In this configuration, the X1 pin is connected
to the external oscillator signal and the X2 pin is left
unconnected.
COUNTDOWN
CHAIN
X1
X2
CRYSTAL
CL1CL2
RTC REGISTERS
DS12885
Figure 1. Oscillator Circuit Showing Internal Bias Network
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
Nominal
Frequency
fO
32.768
kHz
Series
Resistance
ESR
50
k
Ω
Load
Capacitance
CL
6pF
Table 1. Crystal Specifications*
*
The crystal, traces, and crystal input pins should be isolated
from RF generating signals. Refer to Application Note 58:
Crystal Considerations for Dallas Real-Time Clocks
for
additional specifications.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS12887A+ | 功能描述:实时时钟 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 |
| DS1290 | 功能描述:计数器移位寄存器 RoHS:否 制造商:Texas Instruments 计数器类型: 计数顺序:Serial to Serial/Parallel 电路数量:1 封装 / 箱体:SOIC-20 Wide 逻辑系列: 逻辑类型: 输入线路数量:1 输出类型:Open Drain 传播延迟时间:650 ns 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装:Reel |
| DS12C887 | 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 |
| DS12C887+ | 功能描述:实时时钟 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 |
| DS12C887A | 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 |
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