• 辐射时钟解决方案EMC73661108F

辐射时钟解决方案EMC73661108F

所属分类: 解决方案 | 发布日期:2020-02-22 06:02:10

辐射时钟解决方案EMC73661108F,专业针对CLK时钟干扰进行扩频,将尖峰的时钟干扰能量以频率抖动方式降低,以满足法规标准要求。

产品详情

1. DESCRIPTION FEATURES

The EMC73661108F is a versatile, 3.3V/2.5V EMI suppressor IC.EMC73661108F accepts an input clock either from a Crystal or from an external reference (AC or DC coupled to XIN/CLKIN) and locks on to it delivering a 1x modulated clock output.

EM73661108A has a Frequency Selection (FS) control that facilitates selecting one of the two frequency ranges within the operating frequency range. Refer to the frequency Selection table for details.

EMC73661108F has a SSEXTR pin to select different deviations depending upon the value of an external resistor connected between SSEXTR and GND.

Modulation Rate (MR) control selects two different Modulation Rates.

EMC73661108F operates from a 3.3V/2.5V supply and is available in an 8 pin TDFN(2X2) COL packages, over Commercial temperature range.

2. FEATURES

  • 1x, LVCMOS Peak EMI Reduction
  • Input /Output frequency
  • 10MHz - 70MHz @ 2.5V
  • 10MHz - 80MHz @ 3.3V
  • Analog Spread Selection
  • Mod Rate selection option
  • Supply Voltage: 2.5V±0.2V
    3.3V±0.3V
  • 8pin TSSOP, TDFN(2x2) COL Packages
  • Commercial temperature range
  • The First True Drop-in Solution

3. APPLICATION

  • Car stereo, GPS
  • Notebook, MID, Monitors, Top-set Box
  • Cellular Handsets and Accessories
  • NCR,DVR, Fiber Optic Transceiver
  • Industrial Control Products

4. BLOCK DIAGRAM

EMC73661108F

 

PIN DESCRIPTION
(1) XIN / CLKIN
接时钟晶振

(2) XOUT Output
接时钟晶振

(3 )FS
时钟频率选择

(4 )GND
接参考地

(5) Mod OUT
扩频输出端子,接芯片时钟输入

(6) MR
输入频率选择。

(7) SSEXTR
通过外部电阻至GND的扩展范围选择

(8) VDD
接电源2.5V / 3.3V

5. Frequency setting

F0F1Input frequency range
HH10 MHz to 30 MHz
LH66 MHz to 134 MHz
HL20 MHz to 67 MHz
LL40 MHz to 80 MHz
原始测试数据
before EM73661108A
添加EMC73661108F滤波器之后
after EM73661108A

使用步骤

1、将主板上有CLK时钟干扰的晶振取下来,然后焊好连接到芯片EMC73661108F的pin1与pin2。
2、配置芯片EMC73661108F的pin3、pin6,举例如果主板的MCU频率是24MHz(10MHz~30MHz都是同一个区间,都是一样的配置F0=H、F1=H),那么就应该将F0\F1配置为高电平,一般是接10k ohm电阻接3.3V或者2.5V。

F0, F1 frequency setting
3、配置芯片EMC73661108F的pin7进行下拉或者悬空,改变不同的电阻值可以改变不同扩频的百分比,可以将CLK时钟干扰扩频展宽,从而减小干扰。电阻越小扩频的百分比越大、反之越小,开路为不扩频。接地为扩频最大,也就是效果最好。
EMC73661108F pin7
4、配置芯片EMC73661108F的pin4接地,接3.3v或者2.5V的GND。
5、配置芯片EMC73661108F的pin8接电源,接3.3v或者2.5V的电源。
6、最后,配置芯片EMC73661108F上述的脚位,然后pin5 就有信号输出了,将pin5接主板MCU的晶振输入脚。


注意事项

1、建议对芯片EMC73661108F的VCC输入端,加一个BEAD磁珠对VCC滤波,减小晶振的干扰串入主板电源。
2、建议对芯片EMC73661108F的ModOUT输出端,加小电阻例如几欧姆的电阻匹配主板MCU的输入阻抗,减小信号反射与让MCU输入信号幅度为最大防止驱动不了。
3、建议对芯片EMC73661108F的pin4、pin8加滤波电容(电源与地之间加,最小环路最好),0.1uf、1000pf滤波。
4、建议对芯片EMC73661108F的pin8串Bead磁珠滤波(尽量靠近芯片EMC73661108F),建议1000ohm~2000ohm之间。
5、如果遇到其它依然解决不了的问题,可以联系曾工 139 2899 3907

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