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参数资料
| 型号： | DS17887-3-IND |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 3/31页 |
| 文件大小： | 0K |
| 描述： | IC RTC 3V 8K NV RAM 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： | 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： | -40°C ~ 85°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 |
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Detailed Description
The DS17x85 is a successor to the DS1285 real-time
clock (RTC). The device provides 18 bytes of real-time
clock/calendar, alarm, and control/status registers and
114 bytes of nonvolatile battery-backed RAM. The
device also provides additional extended RAM in either
2k/4k/8kbytes (DS17285/DS17485/DS17885). A time-
of-day alarm, six maskable interrupts with a common
interrupt output, and a programmable square-wave
output are available. It also operates in either 24-hour
or 12-hour format with an AM/PM indicator. A precision
temperature-compensated circuit monitors the status of
VCC. If a primary power-supply failure is detected, the
device automatically switches to a backup supply. The
backup supply input supports a primary battery, such
as a lithium coin cell. The device is accessed by a mul-
tiplexed address/data bus.
Oscillator Circuit
The DS17x85 uses an external 32.768kHz crystal. The
oscillator circuit does not require any external resistors
or capacitors to operate. Table 1 specifies several
crystal parameters for the external crystal, and Figure 2
shows a functional schematic of the oscillator circuit.
The oscillator is controlled by an enable bit in the con-
trol register. Oscillator startup times are highly depen-
dent upon crystal characteristics, PC board leakage,
and layout. High ESR and excessive capacitive loads
are the major contributors to long startup times. A cir-
cuit using a crystal with the recommended characteris-
tics and proper layout usually starts within one second.
An external 32.768kHz oscillator can also drive the
DS17x85. In this configuration, the X1 pin is connected
to the external oscillator signal and the X2 pin is left
unconnected.
Clock Accuracy
The accuracy of the clock is dependent upon the accu-
racy of the crystal and the accuracy of the match
between the capacitive load of the oscillator circuit and
the capacitive load for which the crystal was trimmed.
Additional error will be added by crystal frequency drift
caused by temperature shifts. External circuit noise
coupled into the oscillator circuit may result in the clock
running fast. Figure 3 shows a typical PC board layout
for isolation of the crystal and oscillator from noise.
Refer to
Application Note 58: Crystal Considerations
with Dallas Real-Time Clocks for detailed information.
Clock Accuracy (DS17287,
DS17487, and DS17887)
The encapsulated DIP (EDIP) modules are trimmed at
the factory to ±1 minute per month accuracy at 25°C.
DS17285/DS17287/DS17485/DS17487/DS17885/DS17887
Real-Time Clocks
____________________________________________________________________
11
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
Nominal
fO
32.768
kHz
Series
Resistance
ESR
50
k
Ω
Load
Capacitance
CL
6 or
12.5
pF
Table 1. Crystal Specifications* (DS17x85
Only)
*
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 addi-
tional specifications.
COUNTDOWN
CHAIN
X1
X2
CRYSTAL
CL1CL2
RTC REGISTERS
DS17285/87
DS17485/87
DS17885/87
Figure 2. Oscillator Circuit Showing Internal Bias Network
LOCAL GROUND PLANE (TOP LAYER)
CRYSTAL
GND
X2
X1
NOTE: AVOID ROUTING SIGNAL LINES
IN THE CROSSHATCHED AREA
(UPPER LEFT QUADRANT) OF
THE PACKAGE UNLESS THERE IS
A GROUND PLANE BETWEEN THE
SIGNAL LINE AND THE DEVICE PACKAGE.
Figure 3. Layout Example
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| DS17887-3IND+ | 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 |
| DS17887-5 | 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 |
| DS17887-5 IND | 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 |
| DS17887-5+ | 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 |
| DS17887-5IND | 功能描述:IC RTC 5V 8K NV RAM 24-EDIP RoHS:否 类别:集成电路 (IC) >> 时钟/计时 - 实时时钟 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- 类型:时钟/日历 特点:警报器，闰年，SRAM 存储容量:- 时间格式:HH:MM:SS（12/24 小时） 数据格式:YY-MM-DD-dd 接口:SPI 电源电压:2 V ~ 5.5 V 电压 - 电源，电池:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-WDFN 裸露焊盘 供应商设备封装:8-TDFN EP 包装:管件 |
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