石英溫度感測器溫度量測之電路設計與製作

目前市面上溫度偵測的應用電路相當的廣泛，但卻不容易找尋到石英溫度感測器相關的應用電路，本研究主要是針對本研究室所開發出的3代石英溫度感測器進行電路分析設計與實作。第一代石英溫度感測器使用基頻為10MHz (0.1us)，因此應用電路的計時能力至少需能偵測到0.1us，這對於多數的MCU(Micro Controller Unit)而言是無法完成的，所以只能利用外部高速計數器(TTL74LS93)電路去計數石英溫度感測器所產生的頻率值，再將計數結果經由並列輸入串列輸出移位暫存器(TTL 74LS165A)抓取24位元的資料，以串列的方式將資料傳送至MCU (AT89C55)，最後經MCU運算後將正確的溫度值顯示於LCD顯示器上。經實際測試後發現第一代電路實際可測得的精度為0.01℃。第二代石英溫度感測器使用基頻為19.53125KHz(內部除以512倍頻，19.531KHz = 10MHz/512)，改善了第一代晶片高頻信號偵測不易的問題，此低頻信號極易由MCU直接偵測，可直接利用MCU內建的計數器直接計數，並將正確的溫度值顯示於LCD顯示器上。經實際測試後發現第二代電路可測得的實際精度為0.6℃。第三代石英溫度感測器是使用基頻為1.25MHz(內部除以8倍頻，1.25MHz = 10MHz/8)，改善了第一代晶片高頻信號偵測不易的問題，同時也改善了第二代晶片精度不高的問題，此種頻率可使用高速DSP(Digital Signal Processor)的計數器直接計數，並將正確的溫度值顯示於LCD顯示器上。經實際測試後發現第三代電路可測得的實際精度為0.01℃。綜合上述三代石英溫度感測器電路皆能準確的運作，證明吾人所設計的硬體電路及韌體程式皆為正確的設計。未來可將此技術運用在實際的商品上。

關鍵字

石英；溫度感測器；電路設計

並列摘要

Application of the current market temperature detection circuit is quite extensive, but not easy to find quartz temperature sensors related to the applied circuit. This study was developed by our laboratory for the three generations of quartz temperature sensor for Circuit Analysis Design and Implementation. The fundamental frequency that the first generation of quartz temperature sensor used is 10MHz (0.1us), so the applied circuit's timing ability can be detected at least 0.1us, which for most of the MCU (Micro Controller Unit) can not be done, so we can only use an external high-speed counter (TTL74LS93) quartz temperature sensor circuit to count the frequency value generated, and then count the results by parallel input serial output shift register (TTL 74LS165A) 24-bit capture information to serial way to transfer data to MCU (AT89C55). MCU operation will last through the correct temperature value shown on the LCD display. After the practical test, we discovered that the first generation of the actual circuit measured precision is 0.01℃. The fundamental frequency that the second generation of quartz temperature sensor used is 19.531KHz (internal divided by 512 frequency multiplication, 19.531KHz = 10MHz/512). This has improved high-frequency signal problem which was not easy to be detected for the first generation. The low frequency signal can easily be detected directly by the MCU, and it can be counted directly by the MCU built-in counter, and the correct temperature value will be displayed on the LCD display. After the practical test, we discovered that the second generation of the actual circuit measured precision is 0.6℃. The fundamental frequency that the third generation of quartz temperature sensor used is 1.25MHz (internal, inter 8 multiplier, 1.25MHz = 10MHz / 8). This has not only improved high-frequency signal problem which is not easy to be detected for the first generation but also improved the precision problem of second generation chip which is not high. Frequency of use of such high-speed DSP (Digital Signal Processor) to counter direct counting, and the correct value of the temperature will be displayed on the LCD display. After the practical test, we discovered that the third generation of the actual circuit measured precision is 0.01℃. The above three generations of quartz temperature sensor integrated circuit all can be accurately operated. All proved that both my hardware circuit design and firmware program design are correct. The future of such technology can be used in the actual products.