卫星导航是空间信息基础设施,北斗卫星导航系统空间段由5颗静止轨道卫星和30颗非静止轨道卫星组成，中国计划2012年左右，“北斗”系统将覆盖亚太地区，2020年左右覆盖全球。中国正在实施北斗卫星导航系统建设，已成功发射16颗北斗导航卫星。根据系统建设总体规划，2012年左右，系统将首先具备覆盖亚太地区的定位、导航和授时以及短报文通信服务能力。2020年左右，建成覆盖全球的北斗卫星导航系统.为什么现在的卫星导航这么受欢迎,实际上,卫星是可以精确的知道所需要的位置,只需要使用采用过DSB221SDN温补晶振的接收器,就可以很快的定位出想要知道,或者是指定目标性的地点方位.中国北斗卫星导航系统是继美国GPS、俄罗斯格洛纳斯、欧洲伽利略之后的全球第四大卫星导航系统,世界级别的产品选电子配件也是容不得有半点闪失的.晶振称之为线上的心脏,最主要的是因为石英晶振就是整个电路板的中心点,只要稍稍有一点点的误差,那就会使得整个板子"瘫痪".这可不是开啥国际玩笑,并且这也一点也不好笑.温补晶振一直都是以高精度高质量为重任。
    随着时间的变化,科学的进步,不少的产品都采用到了数字化补偿技术.渐渐的TCXO晶振就慢慢的被推向了全世界.数字化的补偿的温补晶振又叫DTCXO,还有种单片机进行补偿的温补晶振称之为MCXO.数字化补偿技术可以实现晶振自动温度补偿,让石英晶体振荡器的频率稳定度非常高.同样也可以适应更宽的工作温度范围.温补晶振被广泛应用到北斗定位系统,GPS卫星导航仪等其它领域.GPS定位导航系统是温补晶振1XXB26000MAA用得比较多。
    现在国行版的2520温补晶振已经稍入街头,对,大多数都是因为在国内需要这颗料的时候而又突然单的给断货了.之前的是DSB221SDA晶振,是日本产的,可能也是因为不想让国内的定位系统及科技迅速发展起来,搞了个紧张的缺货状态.为了能够及时的供货国内也有好几家晶振厂家也开始投入到温补晶振的生产线中.国内产的量是可以跟上了,但是质量却还是比不上国外的先进技.精度跟不上节奏.尽管现在很多晶振厂家都有在调整.但是对于要求不是那么高的定位系统的话.用上去是已经足够了.比如,现在很流行的摩拜单车.小黄,小蓝,小铭同学啊等.逐步个都出来了.但并不是所有的摩拜单车都是用的1XXB26000MAA晶振,因为单车量要多,要的单价也是要便宜,像DSB221SDN晶振的来货成本也是很高的,摩拜公司是承受不来,只是采用几毛钱的热敏晶振.同样也拥有定位功能,但是效果却是没有那么好.1XXB26000MAA晶振能精确到1米,热敏晶振却只能精确到50米的范围.所以经常性的搞出自行车丢了找了好几天也没找回来的囧状。
    很多客户都会经常在问温补晶振也是属于有源晶振的一种,那为什么会和石英晶体振荡器会有着天大的区别呢,一个在天上,一个在地下.温补晶振与普通的石英晶体振荡器的不同就是温补晶振的精度会比石英晶体振荡器的性能要更高,稳定性会更强.对于晶振频率来说,温补晶振可以起到一个温度补偿的作用.温补晶振也称TCXO晶振,传统的TCXO晶振提通过采用模拟器件进行温度补偿,通过改变振荡回路中的 负载电容等模拟器件让其随着温度变化来补偿晶体谐振器由于环境温度变化所生产的频率漂移.
Electrical Characteristics (TA=-40~+85?C, LOAD_R//C=10kΩ//10pF, VCC=+1.8V or +2.2V or +2.8V, unless otherwise noted)
Item   Conditions  Limits         unit   Notesmin.         typ    max.
1         Current Consumption          -        -        1.5    mA   
2         Output Level              0.8    -        -        VP-P  1
3         Symmetry  GND level (DC cut)       40/60         -        60/40         %     
4         Frequency Stability 1.Tolerance      After 2 times reflow    -        -        ±1.5  ppm  2,3
2.vs Temperature TA=-30~+85?C     -        -        ±0.5  ppm  4
TA=-40~-30?C       -        -        ±1.0  ppm  4
3.vs Drift Rate/Slope     @ 0.3?C/s                 ±10.0          ppb/s        
4.vs Hysteresys           -        -        ±0.6  ppm 
5.vs Supply Voltage       VCC=+1.8V±5%,+2.2V±5%,+2.8V±5%      -        -        ±0.1  ppm 
6.vs Load Variation        LOAD_R//C=(10kΩ//10pF)±10%    -        -        ±0.1  ppm 
7.vs Aging   TA=Room ambient       -        -        ±1.0  ppm/year  
TA=Room ambient        -        -        ±1.5  ppm/2years       
TA=Room ambient        -        -        ±2.5  ppm/5years       
TA=Room ambient        -        -        ±5.0  ppm/10years     
5         G Sensitivity        Gamma Vector of all 3axes from 30 to 1500Hz        -        -        ±2.0  ppb/G       
6         Start Up Time     @90% of final VOUT level    -        -        2.0    ms   
7         SSB Phase Noise Relative to f0 level offset 1Hz       -        -        -50    dBc/Hz      
Relative to f0 level offset 5Hz         -        -        -73    dBc/Hz      
Relative to f0 level offset 10Hz       -        -        -80    dBc/Hz      
Relative to f0 level offset 100Hz     -        -        -106  dBc/Hz      
Relative to f0 level offset 1kHz       -        -        -134  dBc/Hz      
Relative to f0 level offset 10kHz     -        -        -144  dBc/Hz      
Relative to f0 level offset 100kHz   -        -        -152  dBc/Hz      
Notes 1. Clipped sine wave (DC-coupled) 2. Ref. to nominal frequency 3. Please leave after reflow in 2h or more at room ambient. 4. Ref. to frequency (TA=+25?C)
Mechanical Characteristics All test is performed after 3times reflow (Clause.13) except 10.10 (Resistance to soldering heat) Item     Description         Requirements    
Drop   Natural drop (On concrete) Mounting on the set or test fixture.(Total weight 100g) Height : 150cm Direction : X,Y,Z, 6directions Test cycle : 3cycles Reference specification : EIAJ-ED-4702A Method5         df/f=<±1.0ppm
Vibration     Sweep range : 10~500Hz Sweep speed : 11min/cycle Amplitude : 1.5mm (10~55Hz) Acceleration : 200m/s2 (55~500Hz) Direction : X,Y,Z, 3directions Test cycle : 10cycles Reference specification : IEC 60068-2-6     df/f=<±0.5ppm  
Shock Acceleration : 1000m/s2 Direction : X,Y,Z, 6directions Duration : 6ms Test cycle : 3cycles/each directions Reference specification : IEC 60068-2-27         df/f=<±0.5ppm  
PCB bend strength         PWB : t=1.6mm Pressure speed : 1.0mm/s Bend width : 1 2 3mm Duration : 10±1s Reference specification : IEC 60068-2-21 Ue1   df/f=<±0.5ppm No visible damage. No leak damage.       
Adherence nature          PWB : t=1.6mm Direction : X,Y, 2directions Pressure : 10N Duration : 10±1s Reference specification : IEC 60068-2-21 Ue3         df/f=<±0.5ppm No visible damage. No leak damage.       
Package strength Pressure : 10N Duration : 10±1s Reference specification : IEC 60068-2-77   df/f=<±0.5ppm No mechanical damage. No leak damage.   
 Gross leak It is immersed for 3min into +125±5?C Chlorofluorocarbon (CFCs) liquid. Reference specification : IEC 60068-2-17  No continuous air bubbles.    
Fine leak     It shall be measured by the helium leak detector after pressurization for 60min by the pressure of (3.92±0.49) x105 Pa in a helium gas atmosphere. Reference specification : IEC 60068-2-17      Less than 1.0x10-9Pa m3/s. 
Solderability         Solder bath temperature : +245±5?C Duration : 3±0.3s Reference specification : IEC 60068-2-58    A new uniform coating of solder shall cover a minimum of 95% of the surface being immersed.
 Resistance to soldering heat         1) Solder iron method Bit size : B(φ3) Bit temperature : +350±10?C Duration : 3+1/-0s /each terminal It shall be measured after 2h at room temperature, humidity. Reference specification : IEC 60068-2-20         df/f=<±0.5ppm dVOUT=<±0.2VP-P No visible damage.        
2) Reflow In refer to temperature profile shown in clause13. Test cycle : 3cycles It shall be measured after 2h at room temperature, humidity. Reference specification : IEC 60068-2-58         df/f=<±1.0ppm dVOUT=<±0.2VP-P No visible damage.    
Environmental Characteristics         Item         Description          Requirements
1         Low temperature storage     Temperature : -40±3?C Duration : 1000h It shall be measured after 2h at room temperature, humidity. Reference specification : IEC 60068-2-1 Ab    df/f=<±1.0ppm dVOUT=<±0.2VP-P The electrical characteristics are satisfied.
2         High temperature storage    Temperature : +85±2?C Duration : 1000h It shall be measured after 2h at room temperature, humidity. Reference specification : IEC 60068-2-2 Bb     df/f=<±1.0ppm dVOUT=<±0.2VP-P The electrical characteristics are satisfied.
3         Humidity    Temperature : +85±2?C R.H. 85±5% Duration : 1000h It shall be measured after 2h at room temperature, humidity. Reference specification : IEC 60068-2-3          df/f=<±1.0ppm dVOUT=<±0.2VP-P The electrical characteristics are satisfied.
4         HTB  Temperature : +85±2?C Duration : 1000h BIAS : Max value of supply voltage It shall be measured after 2h at room temperature, humidity. Reference specification : IEC 60068-2-2 Bb        df/f=<±1.0ppm dVOUT=<±0.2VP-P The electrical characteristics are satisfied.
5         THB  Temperature : +40±2?C R.H. 90~95% Duration : 1000h BIAS : Max value of supply voltage It shall be measured after 2h at room temperature, humidity. Reference specification : IEC 60068-2-3         df/f=<±1.0ppm dVOUT=<±0.2VP-P The electrical characteristics are satisfied.
6         Thermal shock    Thermal shock : -40±3?C : 0.5h ⇔ +85±2?C : 0.5h Test cycle : 200cycles Shift time : 2~3min It shall be measured after 2h at room temperature, humidity. Reference specification : IEC pub.68-2-14.Na          df/f=<±1.0ppm dVOUT=<±0.2VP-P The electrical characteristics are satisfied.
7         ESD   Model : Machine Model (MM) V=±200V (C1=200pF, R1=0Ω) Number of times : 3times Each terminal except common terminal. (Connect to test terminal) Reference specification : EIA/JESD22-A114        df/f=<±1.0ppm dVOUT=<±0.2VP-P The electrical characteristics are satisfied.
Model : Human Body Model (HBM)                       V=±1500V (C1=100pF, R1=1500Ω) df/f=<±1.0ppm          Number of times : 3times         dVOUT=<±0.2VP-P              Each terminal except common terminal.         The electrical characteristics                (Connect to test terminal)    are satisfied.           Reference specification : EIA/JESD22-A115