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参数资料
| 型号： | 1337DVGI |
| 厂商： | INTEGRATED DEVICE TECHNOLOGY INC |
| 元件分类： | 时钟/数据恢复及定时提取 |
| 英文描述： | REAL TIME CLOCK, PDSO8 |
| 封装： | 3 MM, ROHS COMPLIANT, MSOP-8 |
| 文件页数： | 19/24页 |
| 文件大小： | 362K |
| 代理商： | 1337DVGI |
IDT1337
REA LTIME CLOCK WITH SERIAL INTERFACE
RTC
IDT REAL-TIME CLOCK WITH I2C SERIAL INTERFACE
4
IDT1337
REV J 111009
Note: IDT1337CSRI integrates a standard 32.768 kHz
crystal in the package and contributes an additional
frequency error of 10ppm at nominal VCC (+3.3 V) and
TA=+25°C.
ESR (Effective Series Resistance)
Choose the crystal with lower ESR. A low ESR helps the
crystal to start up and stabilize to the correct output
frequency faster compared to high ESR crystals.
Frequency Tolerance
The frequency tolerance for 32 KHz crystals should be
specified at nominal temperature (+25°C) on the crystal
manufacturer datasheet. The crystals used with IDT1337
typically have a frequency tolerance of +/-20ppm at +25°C.
Specifications for a typical 32 kHz crystal used with our
device are shown in the table below.
PCB Design Consideration
Signal traces between IDT device pins and the crystal
must be kept as short as possible. This minimizes
parasitic capacitance and sensitivity to crosstalk and
EMI. Note that the trace capacitances play a role in the
effective crystal load capacitance calculation.
Data lines and frequently switching signal lines should be
routed as far away from the crystal connections as
possible. Crosstalk from these signals may disturb the
oscillator signal.
Reduce the parasitic capacitance between X1 and X2
signals by routing them as far apart as possible.
The oscillation loop current flows between the crystal and
the load capacitors. This signal path (crystal to CL1 to
CL2 to crystal) should be kept as short as possible and
ideally be symmetric. The ground connections for both
capacitors should be as close together as possible.
Never route the ground connection between the
capacitors all around the crystal, because this long
ground trace is sensitive to crosstalk and EMI.
To reduce the radiation / coupling from oscillator circuit,
an isolated ground island on the GND layer could be
made. This ground island can be connected at one point
to the GND layer. This helps to keep noise generated by
the oscillator circuit locally on this separated island. The
ground connections for the load capacitors and the
oscillator should be connected to this island.
PCB Layout
PCB Assembly, Soldering and Cleaning
Board-assembly production process and assembly quality
can affect the performance of the 32 KHz oscillator.
Depending on the flux material used, the soldering process
can leave critical residues on the PCB surface. High
humidity and fast temperature cycles that cause humidity
condensation on the printed circuit board can create
process residuals. These process residuals cause the
insulation of the sensitive oscillator signal lines towards
each other and neighboring signals on the PCB to decrease.
High humidity can lead to moisture condensation on the
surface of the PCB and, together with process residuals,
reduce the surface resistivity of the board. Flux residuals on
the board can cause leakage current paths, especially in
humid environments. Thorough PCB cleaning is therefore
highly recommended in order to achieve maximum
performance by removing flux residuals from the board after
assembly. In general, reduction of losses in the oscillator
circuit leads to better safety margin and reliability.
Parameter
Symbol
Min
Typ
Max Units
Nominal Freq.
fO
32.768
kHz
Series Resistance
ESR
50
k
Load Capacitance
CL
7pF
1337
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| 1374610-3 | INTERCONNECTION DEVICE |
相关代理商/技术参数 |
参数描述 |
|---|---|
| 1337DVGI8 | 制造商:Integrated Device Technology Inc 功能描述:REAL TIME CLOCK SERL 8TSSOP - Tape and Reel |
| 1337G0 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Peripheral IC |
| 1337G1 | 功能描述:重负荷电源连接器 PCB45 HORIZ (TOP) RA LP CONT. RoHS:否 制造商:Hirose Connector 系列:PS2 产品类型:Connectors 位置/触点数量: 端接类型:Crimp 触点材料: 触点电镀:Gold 电压额定值: 电流额定值:300 A 附件类型: |
| 1337G2 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Peripheral IC |
| 1337GCSRI | 功能描述:实时时钟 实时时钟 with Embedded Crystal 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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