衛(wèi)星導航是空間信息基礎(chǔ)設(shè)施,北斗衛(wèi)星導航系統(tǒng)空間段由5顆靜止軌道衛(wèi)星和30顆非靜止軌道衛(wèi)星組成，中國計劃2012年左右，“北斗”系統(tǒng)將覆蓋亞太地區(qū)，2020年左右覆蓋全球。中國正在實施北斗衛(wèi)星導航系統(tǒng)建設(shè)，已成功發(fā)射16顆北斗導航衛(wèi)星。根據(jù)系統(tǒng)建設(shè)總體規(guī)劃，2012年左右，系統(tǒng)將首先具備覆蓋亞太地區(qū)的定位、導航和授時以及短報文通信服務(wù)能力。2020年左右，建成覆蓋全球的北斗衛(wèi)星導航系統(tǒng).為什么現(xiàn)在的衛(wèi)星導航這么受歡迎,實際上,衛(wèi)星是可以精確的知道所需要的位置,只需要使用采用過DSB221SDN溫補晶振的接收器,就可以很快的定位出想要知道,或者是指定目標性的地點方位.中國北斗衛(wèi)星導航系統(tǒng)是繼美國GPS、俄羅斯格洛納斯、歐洲伽利略之后的全球第四大衛(wèi)星導航系統(tǒng),世界級別的產(chǎn)品選電子配件也是容不得有半點閃失的.晶振稱之為線上的心臟,最主要的是因為石英晶振就是整個電路板的中心點,只要稍稍有一點點的誤差,那就會使得整個板子"癱瘓".這可不是開啥國際玩笑,并且這也一點也不好笑.溫補晶振一直都是以高精度高質(zhì)量為重任。
    隨著時間的變化,科學的進步,不少的產(chǎn)品都采用到了數(shù)字化補償技術(shù).漸漸的TCXO晶振就慢慢的被推向了全世界.數(shù)字化的補償?shù)臏匮a晶振又叫DTCXO,還有種單片機進行補償?shù)臏匮a晶振稱之為MCXO.數(shù)字化補償技術(shù)可以實現(xiàn)晶振自動溫度補償,讓石英晶體振蕩器的頻率穩(wěn)定度非常高.同樣也可以適應(yīng)更寬的工作溫度范圍.溫補晶振被廣泛應(yīng)用到北斗定位系統(tǒng),GPS衛(wèi)星導航儀等其它領(lǐng)域.GPS定位導航系統(tǒng)是溫補晶振1XXB26000MAA用得比較多。
    現(xiàn)在國行版的2520溫補晶振已經(jīng)稍入街頭,對,大多數(shù)都是因為在國內(nèi)需要這顆料的時候而又突然單的給斷貨了.之前的是DSB221SDA晶振,是日本產(chǎn)的,可能也是因為不想讓國內(nèi)的定位系統(tǒng)及科技迅速發(fā)展起來,搞了個緊張的缺貨狀態(tài).為了能夠及時的供貨國內(nèi)也有好幾家晶振廠家也開始投入到溫補晶振的生產(chǎn)線中.國內(nèi)產(chǎn)的量是可以跟上了,但是質(zhì)量卻還是比不上國外的先進技.精度跟不上節(jié)奏.盡管現(xiàn)在很多晶振廠家都有在調(diào)整.但是對于要求不是那么高的定位系統(tǒng)的話.用上去是已經(jīng)足夠了.比如,現(xiàn)在很流行的摩拜單車.小黃,小藍,小銘同學啊等.逐步個都出來了.但并不是所有的摩拜單車都是用的1XXB26000MAA晶振,因為單車量要多,要的單價也是要便宜,像DSB221SDN晶振的來貨成本也是很高的,摩拜公司是承受不來,只是采用幾毛錢的熱敏晶振.同樣也擁有定位功能,但是效果卻是沒有那么好.1XXB26000MAA晶振能精確到1米,熱敏晶振卻只能精確到50米的范圍.所以經(jīng)常性的搞出自行車丟了找了好幾天也沒找回來的囧狀。
    很多客戶都會經(jīng)常在問溫補晶振也是屬于有源晶振的一種,那為什么會和石英晶體振蕩器會有著天大的區(qū)別呢,一個在天上,一個在地下.溫補晶振與普通的石英晶體振蕩器的不同就是溫補晶振的精度會比石英晶體振蕩器的性能要更高,穩(wěn)定性會更強.對于晶振頻率來說,溫補晶振可以起到一個溫度補償?shù)淖饔?溫補晶振也稱TCXO晶振,傳統(tǒng)的TCXO晶振提通過采用模擬器件進行溫度補償,通過改變振蕩回路中的 負載電容等模擬器件讓其隨著溫度變化來補償晶體諧振器由于環(huán)境溫度變化所生產(chǎn)的頻率漂移.
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