外文翻譯----數(shù)字溫濕度傳感器(sht 1x sht 7x)

1、<p>　　附錄三 外文翻譯</p><p><b>　　外文資料</b></p><p>　　SHT1x / SHT7x</p><p>　　Humidity & Temperature Sensor </p><p>　　- Relative humidity and tempe

2、rature sensors</p><p>　　- Dew point</p><p>　　- Fully calibrated, digital output</p><p>　　- Excellent long-term stability</p><p>　　- No external components required</

3、p><p>　　- Ultra low power consumption</p><p>　　- Surface mountable or 4-pin fully interchangeable</p><p>　　- Small size</p><p>　　- Automatic power down</p><p>

4、;　　SHT1x / SHT7x Product Summary</p><p>　　The SHTxx is a single chip relative humidity and temperature multi sensor module comprising a calibrated digital output. Application of industrial CMOS processes wit

5、h</p><p>　　patented micro-machining (CMOSens® technology) ensures highest reliability and excellent long term stability. The device includes a capacitive polymer sensing element for relative humidity an

6、d a bandgap temperature sensor. Both are seamlessly coupled to a 14bit analog to digital converter and a serial interface circuit on the same chip. This results in superior signal quality, a fast response time and insens

7、itivity to external disturbances (EMC) at a very competitive price.Each SHTxx is individu</p><p>　　Applications</p><p><b>　　_ HVAC</b></p><p>　　_ Automotive</p>&

8、lt;p>　　_ Consumer Goods</p><p>　　_ Weather Stations </p><p>　　_ Humidifiers</p><p>　　_ Dehumidifiers</p><p>　　_ Test & Measurement</p><p>　　_ Dat

9、a Logging</p><p>　　_ Automation</p><p>　　_ White Goods</p><p><b>　　_ Medical</b></p><p>　　2 Interface Specifications</p><p>　　Figure 2 Typical

10、application circuit</p><p>　　2.1 Power Pins</p><p>　　The SHTxx requires a voltage supply between 2.4 and 5.5 V. After powerup the device needs 11ms to reach its “sleep” state. No commands should

11、 be sent before that time.Power supply pins (VDD, GND) may be decoupled with a 100 nF capacitor.</p><p>　　2.2 Serial Interface (Bidirectional 2-wire)</p><p>　　The serial interface of the SHTxx i

12、s optimized for sensor readout and power consumption and is not compatible with I2C interfaces, see FAQ for details.</p><p>　　2.2.1 Serial clock input (SCK)</p><p>　　The SCK is used to synchron

13、ize the communication between a microcontroller and the SHTxx. Since the interface consists of fully static logic there is no minimum SCK</p><p>　　frequency.</p><p>　　2.2.2 Serial data (DATA)<

14、;/p><p>　　The DATA tristate pin is used to transfer data in and out of the device. DATA changes after the falling edge and is valid on the rising edge of the serial clock SCK. During transmission the DATA line

15、must remain stable while SCK is high. To avoid signal contention the microcontroller should only drive DATA low. An external pull-up resistor (e.g. 10 kΩ ) is required to pull the signal high. (See Figure 2) Pull-up resi

16、stors are often included in I/O circuits of microcontrollers. See Table 5 for de</p><p>　　2.2.3 Sending a command</p><p>　　To initiate a transmission, a “Transmission Start” sequence has to be i

17、ssued. It consists of a lowering of the DATA line while SCK is high, followed by a low pulse on SCK and raising DATA again while SCK is still high.</p><p>　　Figure 3 "Transmission Start" sequence&l

18、t;/p><p>　　The subsequent command consists of three address bits (only “000” is currently supported) and five command bits. The SHTxx indicates the proper reception of a command by pulling the DATA pin low (ACK

19、 bit) after the falling edge of the 8th SCK clock. The DATA line is released (and goes high) after the falling edge of the 9th SCK clock.</p><p>　　2.2.4 Measurement sequence (RH and T)</p><p>　　

20、After issuing a measurement command (‘00000101’ for RH, ‘00000011’ for Temperature) the controller has to wait for the measurement to complete. This takes approximately 11/55/210 ms for a 8/12/14bit measurement. The exac

21、t time varies by up to ±15% with the speed of the internal oscillator. To signal the completion of a measurement, the SHTxx pulls down the data line and enters idle mode. The controller must wait for this “data read

22、y” signal before restarting SCK to readout the data. Measurement </p><p>　　Two bytes of measurement data and one byte of CRC checksum will then be transmitted. The uC must acknowledge each byte by pulling th

23、e DATA line low. All</p><p>　　values are MSB first, right justified. (e.g. the 5th SCK is MSB for a 12bit value, for a 8bit result the first byte is not used). Communication terminates after the acknowledge

24、bit of the CRC data. If CRC-8 checksum is not used the controller may terminate the communication after the measurement dat LSB by keeping ack high. The device automatically returns to sleep mode after the measurement an

25、d communication have ended. Warning: To keep self heating below 0.1 °C the SHTxx should not be active f</p><p>　　2.2.5 Connection reset sequence</p><p>　　If communication with the device is

26、 lost the following signal sequence will reset its serial interface:</p><p>　　While leaving DATA high, toggle SCK 9 or more times. This must be followed by a “Transmission Start” sequence preceding the next

27、command. This sequence resets the</p><p>　　interface only. The status register preserves its content.</p><p>　　Figure 4 Connection reset sequence</p><p>　　2.2.6 CRC-8 Checksum calcu

28、lation</p><p>　　The whole digital transmission is secured by a 8 bit checksum. It ensures that any wrong data can be detected and eliminated.</p><p>　　Please consult application note “CRC-8 Chec

29、ksum Calculation” for information on how to calculate the CRC.</p><p>　　2.3 Status Register</p><p>　　Some of the advanced functions of the SHTxx are available through the status register. The fo

30、llowing section gives a brief overview of these features. A more detailed description is available in the application note “Status Register</p><p>　　Figure 7 Status Register Write Figure 8 Sta

31、tus Register Read</p><p>　　2.3.1 Measurement resolution</p><p>　　The default measurement resolution of 14bit (temperature) and 12bit (humidity) can be reduced to 12 and 8bit. This is especially

32、useful in high speed or extreme low power</p><p>　　applications.</p><p>　　2.3.2 End of Battery</p><p>　　The “End of Battery” function detects VDD voltages below 2.47 V. Accuracy is

33、±0.05 V</p><p>　　2.3.3 Heater</p><p>　　An on chip heating element can be switched on. It will increase the temperature of the sensor by 5-15 °C (9-27 °F). Power consumption will i

34、ncrease by ~8 mA @ 5 V.</p><p>　　Applications:</p><p>　　By comparing temperature and humidity values before and after switching on the heater, proper functionality of both sensors can be verifie

35、d.</p><p>　　? In high (>95 %RH) RH environments heating the sensor element will prevent condensation, improve response time and accuracy</p><p>　　Warning: While heated the SHTxx will show hig

36、her temperatures and a lower relative humidity than with no heating.</p><p>　　3 Converting Output to Physical Values</p><p>　　3.1 Relative Humidity</p><p>　　To compensate for the no

37、n-linearity of the humidity sensor and to obtain the full accuracy it is recommended to convert the readout with the following formula1:</p><p>　　RHlinear = c1 +c2 ?SORH +c3 ? </p><p>　　Table 6

38、 Humidity conversion coefficients Table 7 Temperature compensation coefficient</p><p>　　The humidity sensor has no significant voltage dependency</p><p>　　Figure 10 Conversion from SORH to re

39、lative humidity</p><p>　　3.1.1 Humidity Sensor RH/Temperature compensation</p><p>　　For temperatures significantly different from 25 °C (~77 °F) the temperature coefficient of the RH s

40、ensor should be considered:</p><p>　　RHtrue = (T°C - 25)?(t1 +t2 ?SORH)+RHlinear</p><p>　　3.2 Temperature</p><p>　　The bandgap PTAT (Proportional To Absolute Temperature) tempe

41、rature sensor is very linear by design. Use the following formula to convert from digital readout to</p><p>　　temperature:</p><p>　　Temperatur e = d1 +d2 ?SOT</p><p>　　Table 8 Tempe

42、rature conversion coefficients</p><p>　　For improved accuracies in extreme temperatures with more computation intense conversion formulas see application note “RH and Temperature Non-Linearity Compensation&l

43、t;/p><p>　　3.3 Dewpoint</p><p>　　Since humidity and temperature are both measured on the same monolithic chip, the SHTxx allows superb dewpoint measurements. See application note “Dewpoint calculat

44、ion” for more.</p><p>　　4 Applications Information</p><p>　　4.1 Operating and Storage Conditions</p><p>　　Figure 11 Recommended operating conditions</p><p>　　Conditions

45、 outside the recommended range may temporarily offset the RH signal up to ±3 %RH. After return to normal conditions it will slowly return towards calibration state by itself. See 4.3 “Reconditioning Procedure” to ac

46、celerate this process. Prolonged exposure to extreme conditions may accelerate ageing.</p><p>　　4.2 Exposure to Chemicals</p><p>　　Chemical vapors may interfere with the polymer layers used for

47、capacitive humidity sensors. The diffusion of chemicals into the polymer may cause a shift in both offset and sensitivity. In a clean environment the contaminants will slowly outgas. The reconditioning procedure describe

48、d below will accelerate this process. High levels of pollutants may cause permanent damage to the sensing polymer.</p><p>　　4.3 Reconditioning Procedure</p><p>　　The following reconditioning pro

49、cedure will bring the sensor back to calibration state after exposure to extreme conditions or chemical vapors. 80-90 °C (176-194°F) at < 5 %RH for 24h (baking) followed by 20-30 °C (70-90°F) at &g

50、t; 74 %RH for 48h (re-hydration)</p><p>　　4.4 Temperature Effects</p><p>　　The relative humidity of a gas strongly depends on its temperature. It is therefore essential to keep humidity sensors

51、at the same temperature as the air of which the</p><p>　　relative humidity is to be measured.</p><p>　　If the SHTxx shares a PCB with electronic components that give off heat it should be mounte

52、d far away and below the heat source and the housing must remain well ventilated. To reduce heat conduction copper layers between the SHT1x and the rest of the PCB should be minimized and aslit may be milled in between (

53、see figure 13).</p><p>　　4.5 Membranes</p><p>　　A membrane may be used to prevent dirt from entering the housing and to protect the sensor. It will also reduce peak concentrations of chemical va

54、pors. For optimal response times air volume behind the membrane must be kept to a minimum. For the SHT1x package Sensirion recommends the SF1 filter cap for optimal IP67 protection.</p><p><b>　　4.6 Lig

55、ht</b></p><p>　　The SHTxx is not light sensitive. Prolonged direct exposure to sunshine or strong UV radiation may age the housing.</p><p>　　4.7 Materials Used for Sealing / Mounting</p

56、><p>　　Many materials absorb humidity and will act as a buffer, increasing response times and hysteresis. Materials in the vicinity of the sensor must therefore be carefully chosen.</p><p>　　Recomm

57、ended materials are: All Metals, LCP, POM (Delrin), PTFE (Teflon), PE, PEEK, PP, PB, PPS, PSU, PVDF, PVF For sealing and gluing (use sparingly): High filled epoxy for electronic packaging (e.g. glob top, underfill), and

58、Silicone. Outgassing of these materials may also contaminate the SHTxx (cf. 4.2). Store well ventilated after manufacturing or bake at 50°C for 24h to outgas contaminants before packing.</p><p>　　4.8 Wi

59、ring Considerations and Signal Integrity</p><p>　　Carrying the SCK and DATA signal parallel and in close proximity (e.g. in wires) for more than 10cm may result in cross talk and loss of communication. This

60、may be resolved by routing VDD and/or GND between the two data signals. Please see the application note “ESD, Latchup and EMC” for more information. Power supply pins (VDD, GND) should be decoupled with a 100 nF capacito

61、r if wires are used.</p><p>　　4.9 ESD (Electrostatic Discharge)</p><p>　　ESD immunity is qualified according to MIL STD 883E, method 3015 (Human Body Model at ±2 kV)). Latch-up immunity is

62、provided at a force current of ±100 mA with Tamb = 80 °C according to JEDEC 17. See application note “ESD, Latchup and EMC” for more information.</p><p>　　5 Important Notices</p><p>　　

63、5.1 Warning, personal injury</p><p>　　Do not use this product as safety or emergency stop devices or in any other application where failure of the product could result in personal injury. Failure to</p>

64、;<p>　　comply with these instructions could result in death or serious injury. Should buyer purchase or use SENSIRION AG products for any such unintended or unauthorized application, Buyer shall indemnify and hold

65、 SENSIRION AG and its officers, employees, subsidiaries, affiliates and distributors harmless against all claims, costs, damages and expenses, and reasonable attorney fees arising out of, directly or indirectly, any clai

66、m of personal injury or death associated with such unintended or unauthori</p><p>　　5.2 ESD Precautions</p><p>　　The inherent design of this component causes it to be sensitive to electrostatic

67、discharge (ESD). To prevent ESD-induced damage and/or degradation, take normal ESD precautions when handling this product. See application note “ESD, Latchup and EMC” for moreinformation.</p><p>　　5.3 Warran

68、ty</p><p>　　SENSIRION AG makes no warranty, representation or guarantee regarding the suitability of its product for any particular purpose, nor does SENSIRION AG assume any liability arising out of the appl

69、ication or use of any product or circuit and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters can and do vary in different applications.

70、 All operating parameters,including “Typical” must be validated for each customer app</p><p>　　document and to improve reliability, functions and design.</p><p>　　數(shù)字溫濕度傳感器(SHT 1x/ SHT 7x)</p&

71、gt;<p>　　_ 相對濕度和溫度測量 </p><p><b>　　_ 兼有露點(diǎn)</b></p><p>　　_ 全標(biāo)定輸出，無需標(biāo)定即可互換使用</p><p>　　_ 卓越的長期穩(wěn)定性</p><p>　　_ 兩線制數(shù)字接口，無需額外部件

72、</p><p>　　_ 基于請求式測量，因此低能耗</p><p>　　_ 表面貼片或4 針引腳安裝</p><p><b>　　_ 超小尺寸</b></p><p><b>　　_ 自動休眠</b></p><p>　　SHT1x / SHT7x 產(chǎn)品概述</p&g

73、t;<p>　　SHTxx 系列產(chǎn)品是一款高度集成的溫濕度傳感器芯片， 提供全標(biāo)定的數(shù)字輸出。它采用專利的CMOSens® 技術(shù)，確保產(chǎn)品具有極高的可靠性與卓越的長期穩(wěn)定性。傳感器包括一個(gè)電容性聚合體測濕敏感元件、一個(gè)用能隙材料制成的測溫元件，并在同一芯片上，與14 位的A/D 轉(zhuǎn)換器以及串行接口電路實(shí)現(xiàn)無縫連接。因此，該產(chǎn)品具有品質(zhì)卓越、超快響應(yīng)、抗干擾能力強(qiáng)、極高的性價(jià)比等優(yōu)點(diǎn)。</p><

74、;p>　　每個(gè)傳感器芯片都在極為精確的濕度腔室中進(jìn)行標(biāo)定，以鏡面冷凝式濕度計(jì)為參照。校準(zhǔn)系數(shù)以程序形式儲存在OTP 內(nèi)存中，在標(biāo)定的過程中使用。兩線制的串行接口與內(nèi)部的電壓調(diào)整，使外圍系統(tǒng)集成變得快速而簡單。微小的體積、極低的功耗，使其成為各類應(yīng)用的首選。產(chǎn)品提供表面貼片 LCC 或4 針單排引腳封裝。特殊封裝形式可根據(jù)用戶需求而提供。</p><p>　　應(yīng)用領(lǐng)域

75、 框圖</p><p>　　_ 暖通空調(diào)HVAC </p><p><b>　　_ 汽車</b></p><p><b>　　_ 消費(fèi)品</b></p><p><b>　　_氣象站</b></p><p><b>　

76、　_濕度調(diào)節(jié)器</b></p><p><b>　　_除濕器</b></p><p><b>　　_ 測試及檢測設(shè)備</b></p><p><b>　　_ 數(shù)據(jù)記錄器</b></p><p><b>　　_ 自動控制</b></p>

77、;<p><b>　　_ 家電</b></p><p><b>　　_ 醫(yī)療</b></p><p><b>　　2 接口說明</b></p><p>　　圖 2 典型應(yīng)用電路</p><p><b>　　2.1 電源引腳</b></p

78、><p>　　SHTxx 的供電電壓為2.4~5.5V。傳感器上電后，要等待11ms 以越過“休眠”狀態(tài)。在此期間無需發(fā)送任何指令。電源引腳（VDD，GND）之間可增加一個(gè)100nF 的電容，用以去耦濾波。</p><p>　　2.2 串行接口 (兩線雙向)</p><p>　　SHTxx 的串行接口，在傳感器信號的讀取及電源損耗方面，都做了優(yōu)化處理；但與I2C 接口不

79、兼容，詳情參見 FAQ</p><p>　　2.2.1 串行時(shí)鐘輸入 (SCK)</p><p>　　SCK 用于微處理器與SHTxx 之間的通訊同步。由于接口包含了完全靜態(tài)邏輯，因而不存在最小SCK 頻率。</p><p>　　2.2.2 串行數(shù)據(jù) (DATA)</p><p>　　DATA 三態(tài)門用于數(shù)據(jù)的讀取。DATA 在SCK 時(shí)鐘下

80、降沿之后改變狀態(tài)，并僅在SCK 時(shí)鐘上升沿有效。數(shù)據(jù)傳輸期間，在SCK 時(shí)鐘高電平時(shí)，DATA必須保持穩(wěn)定。為避免信號沖突，微處理器應(yīng)驅(qū)動DATA 在低電平。需要一個(gè)外部的上拉電阻（例如：10kΩ）將信號提拉至高電平（參見圖2）。上拉電阻通常已包含在微處理器的I/O 電路中。詳細(xì)的IO特性，參見表 5。</p><p>　　2.2.3 發(fā)送命令</p><p>　　用一組“ 啟動傳輸”時(shí)序

81、，來表示數(shù)據(jù)傳輸?shù)某跏蓟?。它包括：?dāng)SCK 時(shí)鐘高電平時(shí)DATA 翻轉(zhuǎn)為低電平，緊接著SCK 變?yōu)榈碗娖?，隨后是在SCK 時(shí)鐘高電平時(shí)DATA 翻轉(zhuǎn)為高電平。</p><p>　　圖 3 "啟動傳輸" 時(shí)序</p><p>　　后續(xù)命令包含三個(gè)地址位（目前只支持“000”），和五個(gè)命令位。SHTxx 會以下述方式表示已正確地接收到指令：在第8 個(gè)SCK 時(shí)鐘的下降沿之后

82、，將DATA 下拉為低電平（ACK 位）。在第9 個(gè)SCK 時(shí)鐘的下降沿之后，釋放DATA（恢復(fù)高電平）。</p><p>　　表2 SHT控制命令代碼</p><p>　　2.2.4 測量時(shí)序(RH 和 T)</p><p>　　發(fā)布一組測量命令（‘00000101’表示相對濕度RH，‘00000011’表示溫度T）后，控制器要等待測量結(jié)束。這個(gè)過程需要大約11/

83、55/210ms，分別對應(yīng)8/12/14bit 測量。確切的時(shí)間隨內(nèi)部晶振速度，最多有±15%變化。SHTxx 通過下拉DATA 至低電平并進(jìn)入空閑模式，表示測量的結(jié)束?？刂破髟谠俅斡|發(fā)SCK 時(shí)鐘前，必須等待這個(gè)“數(shù)據(jù)備妥”信號來讀出數(shù)據(jù)。檢測數(shù)據(jù)可以先被存儲這樣控制器可以繼續(xù)執(zhí)行其它任務(wù)在需要時(shí)再讀出數(shù)據(jù)。接著傳輸2 個(gè)字節(jié)的測量數(shù)據(jù)和1 個(gè)字節(jié)的CRC 奇偶校驗(yàn)。uC 需要通過下拉DATA 為低電平，以確認(rèn)每個(gè)字節(jié)。所有

84、的數(shù)據(jù)從MSB 開始，右值有效（例如：對于12bit 數(shù)據(jù)，從第5 個(gè)SCK 時(shí)鐘起算作MSB； 而對于 8bit 數(shù)據(jù)， 首字節(jié)則無意義）。用 CRC 數(shù)據(jù)的確認(rèn)位，表明通訊結(jié)束。如果不使用CRC-8 校驗(yàn)，控制器可以在測量值LSB 后，通過保持確認(rèn)位ack 高電平， 來中止通訊。在測量和通訊結(jié)束后，SHTxx 自動轉(zhuǎn)入休眠模式。</p><p>　　警告：為保證自身溫升低于0.1℃，SHTxx 的激活時(shí)間不要

85、超過15%（例如，對應(yīng)12bit 精度測量，每秒最多進(jìn)行3 次測量）。</p><p>　　2.2.5 通訊復(fù)位時(shí)序</p><p>　　如果與 SHTxx 通訊中斷，下列信號時(shí)序可以復(fù)位串口：當(dāng)DATA 保持高電平時(shí)，觸發(fā)SCK 時(shí)鐘9 次或更多。在下一次指令前，發(fā)送一個(gè)“傳輸啟動”時(shí)序。這些時(shí)序只復(fù)位串口，狀態(tài)寄存器內(nèi)容仍然保留。</p><p>　　圖 4 通

86、訊復(fù)位時(shí)序</p><p>　　2.2.6 CRC-8 校驗(yàn)</p><p>　　數(shù)字信號的整個(gè)傳輸過程由 8bit 校驗(yàn)來確保。任何錯(cuò)誤數(shù)據(jù)將被檢測到并清除。詳情可參閱應(yīng)用說明“CRC-8 校驗(yàn)”。</p><p>　　圖 6 測量時(shí)序概覽 (TS = 啟動傳輸)</p><p><b>　　2.3 狀態(tài)寄存器</b>

87、</p><p>　　SHTxx 的某些高級功能可以通過狀態(tài)寄存器實(shí)現(xiàn)。下面的章節(jié)概括介紹了這些功能。</p><p>　　詳情可參閱應(yīng)用說明“狀態(tài)寄存器”。</p><p>　　圖 7 狀態(tài)寄存器讀 圖 8 狀態(tài)寄存器寫</p><p>　　2.3.1 測量分辨率</p>&

88、lt;p>　　默認(rèn)的測量分辨率分別為14bit（溫度）、12bit（濕度），也可分別降至12bit 和8bit。通常在高速或超低功耗的應(yīng)用中采用該功能。</p><p>　　2.3.2 電量不足</p><p>　　“電量不足”功能可監(jiān)測到Vdd 電壓低于2.47V 的狀態(tài)。精度為±0.05V。</p><p>　　2.3.3 加熱元件</p&

89、gt;<p>　　芯片上集成了一個(gè)可通斷的加熱元件。接通后，可將SHTxx 的溫度提高大約5℃（9℉）。功耗增加8mA@ 5V。</p><p>　　應(yīng)用于：比較加熱前后的溫度和濕度值，可以綜合驗(yàn)證兩個(gè)傳感器元件的性能。</p><p>　　? 在高濕 (>95 %RH) 環(huán)境中，加熱傳感器可預(yù)防結(jié)露，同時(shí)縮短響應(yīng)時(shí)間，提高精度。</p><p>

90、;　　警告: 加熱 SHTxx 后溫度升高、相對濕度降低，較之加熱前，示值略有差異。</p><p>　　3 輸出轉(zhuǎn)換為物理量</p><p><b>　　3.1 相對濕度</b></p><p>　　為了補(bǔ)償濕度傳感器的非線性以獲取準(zhǔn)確數(shù)據(jù)，建議使用如下公式1修正讀數(shù)：</p><p>　　RHlinear = c1

91、+c2 ?SORH +c3 ? </p><p>　　表 6 濕度轉(zhuǎn)換系數(shù) 表 7 溫度補(bǔ)償系數(shù)</p><p>　　濕度傳感器對電壓基本上沒有依賴性。</p><p>　　圖 10 從 SORH 轉(zhuǎn)換到相對濕度</p><p>　　3.1.1 相對濕度對于溫度依賴性的補(bǔ)償</p&g

92、t;<p>　　由于實(shí)際溫度與測試參考溫度25℃ (~77℉)的顯著不同， 應(yīng)考慮濕度傳感器的溫度修正系數(shù)：RHtrue = (T°C - 25)?(t1 +t2 ?SORH)+RHlinear</p><p><b>　　3.2 溫度</b></p><p>　　由能隙材料PTAT (正比于絕對溫度) 研發(fā)的溫度傳感器具有極好的線性。可用如下

93、公式將數(shù)字輸出轉(zhuǎn)換為溫度值：Temperatur e = d1 +d2 ?SOT</p><p>　　表 8 溫度轉(zhuǎn)換系數(shù)</p><p><b>　　3.3 露點(diǎn)</b></p><p>　　由于濕度與溫度經(jīng)由同一塊芯片測量，SHTxx 系列產(chǎn)品可以同時(shí)實(shí)現(xiàn)高質(zhì)量的露點(diǎn)測量?？蓞㈤啈?yīng)用說明“露點(diǎn)計(jì)算”。</p><p>

94、;<b>　　4 應(yīng)用信息</b></p><p>　　4.1 工作與貯存條件</p><p>　　圖 11 建議的工作條件</p><p>　　超出建議的工作范圍可能導(dǎo)致最大3%的RH 信號暫時(shí)性漂移。當(dāng)恢復(fù)到正常工作條件后，傳感器會緩慢自恢復(fù)到校正狀態(tài)?？蓞㈤?.3 小節(jié)的“恢復(fù)處理”以加速恢復(fù)進(jìn)程。在非正常條件下的長時(shí)間使用，會加速產(chǎn)品的

95、老化。</p><p>　　4.2 暴露在化學(xué)物質(zhì)中</p><p>　　用于濕度測量的聚合物會受到化學(xué)蒸汽的侵蝕，化學(xué)物質(zhì)在聚合物中的擴(kuò)散可能導(dǎo)致測量元件精度的漂移與靈敏性下降。在純凈的環(huán)境中，污染物將緩慢釋放。下文所述的恢復(fù)處理將加速實(shí)現(xiàn)這一過程。強(qiáng)化學(xué)污染可能導(dǎo)致傳感器的徹底損壞。</p><p><b>　　4.3 恢復(fù)處理</b>&l

96、t;/p><p>　　暴露在極端工作條件或化學(xué)蒸汽中的傳感器，可通過如下處理，使其恢復(fù)到校準(zhǔn)狀態(tài)。在80-90℃ (176-194℉) 和< 5%RH 的濕度條件下保持 24小時(shí)（烘干）； 隨后在20-30℃ (70-90℉) 和>74%RH 的濕度條件下保持48 小時(shí)（重新水合）</p><p><b>　　4.4 溫度影響</b></p>&

97、lt;p>　　氣體的相對濕度，在很大程度上依賴于溫度。因此在測量濕度時(shí)，應(yīng)盡可能保證濕度傳感器在同一溫度下工作。如果與釋放熱量的電子元件共用一個(gè)印刷線路板，在安裝時(shí)應(yīng)盡可能將SHTxx遠(yuǎn)離電子元件，并安裝在熱源下方，同時(shí)保持外殼的良好通風(fēng)。為降低熱傳導(dǎo)，SHT1x 與印刷電路板其它部分的銅鍍層應(yīng)盡可能最小，并在兩者之間留出一道縫隙。</p><p><b>　　4.5 薄膜</b>&l

98、t;/p><p>　　薄膜可防止灰塵進(jìn)入，以保護(hù)傳感器。同時(shí)會減少化學(xué)蒸汽的濃度。為獲取最佳的響應(yīng)時(shí)間，薄膜內(nèi)的空氣量必須保持在最少。對于SHT1X 封裝系列，盛世瑞恩推薦使用SF1 型過濾罩，以達(dá)到最優(yōu)的IP67 保護(hù)等級。</p><p><b>　　4.6 光線</b></p><p>　　SHTxx 對光線不敏感。但長時(shí)間暴露在太陽光下或強(qiáng)

99、烈的紫外線輻射中，會使外殼老化。</p><p>　　4.7 用于密封和安裝的材質(zhì)</p><p>　　許多材質(zhì)吸收濕氣并將充當(dāng)緩沖器的角色，這會加大響應(yīng)時(shí)間和遲滯。因此傳感器周邊的材質(zhì)應(yīng)謹(jǐn)慎選用。推薦使用的材料有：所有的金屬, LCP,POM (Delrin), PTFE (Teflon), PE, PEEK，PP, PB,PPS, PSU, PVDF, PVF用于密封和粘合的材質(zhì)（保守

100、推薦）：推薦使用充滿環(huán)氧樹脂的方法進(jìn)行電子元件的封裝，或是硅樹脂。這些材料釋放的氣體也有可能污染SHTxx(見4.2)。加工后應(yīng)將傳感器置于通風(fēng)良好處，或在50℃的環(huán)境中干燥24小時(shí)，以使其在封裝前將污染氣體釋放。</p><p>　　4.8 接線注意事項(xiàng)與信號完整性</p><p>　　使SCK和DATA信號線平行并盡可能使間距超過10cm（如使用導(dǎo)線），否則將導(dǎo)致串?dāng)_和信號丟失。解決方

101、法是在兩個(gè)信號線之間放置VDD和/或GND。詳情可參閱應(yīng)用說明“ESD、latch-up和EMC”。如使用導(dǎo)線，應(yīng)在電源引腳（VDD，GND）之間可增加一個(gè)100nF 的電容，用以去耦濾波。</p><p>　　4.9 ESD (靜電釋放)</p><p>　　ESD靜電釋放符合MIL STD 883E method 3015標(biāo)準(zhǔn)。電路閉鎖測試依據(jù)JEDEC 17標(biāo)準(zhǔn)，滿足強(qiáng)制電流在

102、77;100 mA，環(huán)境溫度Tamb = 80℃條件下不閉鎖.</p><p><b>　　5 注意事項(xiàng)</b></p><p>　　5.1 警告，人身傷害</p><p>　　勿將本產(chǎn)品作為安全保護(hù)或急停設(shè)備，以及其它由于本產(chǎn)品故障導(dǎo)致人身傷害的應(yīng)用中。如不遵從此建議，可能導(dǎo)致死亡和嚴(yán)重的人身傷害。</p><p>　

103、　如果將購買或使用任何SENSIRION AG產(chǎn)品這種意外或未經(jīng)授權(quán)的應(yīng)用程序，買方應(yīng)賠償并SENSIRION公司及其高級人員，雇員，子公司，分公司和經(jīng)銷商對所有索賠無害，成本，損失和費(fèi)用，以及合理的律師費(fèi)所產(chǎn)生的直接或間接的任何索賠或人身傷害這種意外或未經(jīng)授權(quán)使用相關(guān)的死亡，甚至如果這種主張稱，SENSIRION AG公司有關(guān)的疏忽設(shè)計(jì)或制造的一部分。</p><p>　　5.2 ESD 靜電釋放的預(yù)防<

104、/p><p>　　由于元件的固有設(shè)計(jì)，導(dǎo)致其對靜電的敏感性。為防止靜電導(dǎo)入的傷害或者降低產(chǎn)品性能，在應(yīng)用本產(chǎn)品時(shí)，請采取必要的防靜電措施。</p><p><b>　　5.3 品質(zhì)保證</b></p><p>　　SENSIRION AG對其產(chǎn)品應(yīng)用在那些特殊的應(yīng)用場合不做任何的保證、擔(dān)保、或是書面陳述。同時(shí)SENSIRION AG對其產(chǎn)品應(yīng)用到產(chǎn)