Integrated humidity sensor ih3605 and Its Application

Source: http://www.ieechina.com/Upload/Tech/748.htmAbstract:　 The integrated humidity sensor ih3605 can adjust the signal in the chip, and has high precision and good linearity. This article introduces its performance and structure features, and provides typical application instances of ih3605. Keywords:Humidity Sensor; integrated circuit; ih3605 Document Identification: Article B No.: 1006-6977 (2000) 01-0009-02

Humidity measurement has been widely used in many fields of industrial production. The ih3605 integrated humidity sensor produced by Honeywell uses the integrated circuit technology to adjust the signal within the integrated circuit. It is widely used because of its advantages such as high precision, good linearity, and strong interconnectivity.1. ih3605 structure and pin IntroductionBecause the size of the flat capacitor electrical capacity formed between two aggregation layers in ih3605 can change with the humidity, the humidity signal can be collected. The aggregation layer can defend against dirt, dust, oil and other harmful substances at the same time. The ih3605 structure and pin definitions are shown in 1 and 2 respectively. Ih3605 is in the form of SIP encapsulation. 2. Main Technical Indicators of ih3605● Power supply voltage: 4 ~ 5.8 V; ● Power supply current: 200 μA (5vdc ); ● Humidity range: 0 ~ 100% RH ● Precision: ± 2% RH (0 ~ 100% RH, 25 ℃, V = 5vdc ); ● Interchangeable: ± 5% Rh (0 ~ 60% RH); ± 8% Rh (90% RH ); ● Linearity: ± 0. 5% Rh (typical ); ● Repeatability: ± 0. 5% RH; ● Stability: ± 1% RH (50% RH, 5 years ); ● Response Time: 15 s (at 25 ℃ and in a slow air flow environment ); ● Operating temperature:-40 ℃ ~ 85 ℃;3. voltage output characteristics of ih3605The ih3605 output voltage is a function of the power supply voltage, humidity, and temperature. When the power supply voltage increases, the output voltage increases proportionally. in actual application, the actual relative humidity value can be calculated using the following two steps. (1) Calculate the relative humidity (rh0) at 25 ℃ according to the following formula. Vout = v dc (0.0062rh0 + 0.16) Among them, Vout is the ih3605 voltage output value, VDC is the ih3605 power supply voltage value, and rh0 is the relative humidity value at 25 ℃. (2) Calculate the actual relative humidity value RH at the current temperature. RH = rh0/(1.0546-0.00216 T) RH indicates the actual relative humidity, and t indicates the current temperature. Unit: ℃. Figure 3 shows the relationship between the output voltage and relative humidity of ih3605.4. Typical applicationsBecause the ih3605 output voltage is high and linear, the circuit does not need to be amplified or adjusted. The ih3605 output signal can be directly sent to the/D converter to complete the conversion from analog to digital. Because the output signal range of ih3605 is 0.8 ~ 3.9 V (25 ℃), so when selecting A/D converter, you should select A/D converter (such as tlc1549) with the function of setting the minimum and maximum values ). The typical application circuit of ih3605 is shown in Figure 4. The core device of ih3605 adopts a single-chip microcomputer, while the/D Converter uses TI's tlc1549 ten-digit serial A/D converter, r1, R2, and R6 set the maximum input voltage of the/D converter. R3, R4, and R7 set the minimum input voltage of the/D converter, the temperature sensor D2 uses Dallas's fully digital integrated temperature measurement circuit, DS18B20, which reads the temperature value from the P10 port and corrects the temperature value to obtain the actual relative humidity value. The circuit diagram has no display and communication components. You can add related circuits as needed.5. Application considerationsThe calibration value of a device with a CP suffix is provided at the factory in the environment of 25 ℃. You can calculate the maximum output voltage and minimum output voltage of the sensor based on the calibration value during use, and set it in the circuit. This device is sensitive to ESD. In order to prevent damage to the device, corresponding ESD protection measures should be taken. To prevent direct exposure to the sensor.