OTC-238 THERMOPILE INFRARED SENSOR Date : Oct. 10, 2000 ▓ Features The thermopile sensor consists of a series of 44 thermoelements, forming a sensitive area of 0.5*0.5 mm2. The sensor is hermetically sealed into a TO-18 metal housing, with optical filter. This standard filter allows measurements to be made in the spectral range above 5µm wavelength. The thermosensor exhibits an almost white noise, comparable to an ohmic resistance. It has a constant signal versus frequency up to its frequency limit, and is directly proportional to incident radiation. ▓ Applications * Ear thermometers; clinic thermometers * Infrared thermometers * Consumer applications: hair dryer, micro-wave oven, air conditioner, refrigerator * Continuous temperature control of manufacturing * Security system * Radiation monitor switch system * Absorbing measurement for gas analysis * Thermoelectric converter * Heat flux flowmeter ▓ Electrical Characteristics Parameter Condition Min. Typ. Max. Unit Number of thermojunctions --- 44 --- Chip size --- 1920*1725 --- µm2 --- 500*500 --- µm2 Thermopile Active area Interference layer Thickness of substrate Siliconsubstrate 600 625 650 µm Resistance of thermopile 25 60 70 80 KΩ Sensitivity With 5-14µm filter 40 55 70 V/W 4*107 7*107 9*107 cm*Hz1/2/W Time Constant --- 30 --- ms Noise voltage --- 34 --- nV/Hz1/2 NEP --- 0.8 --- nW/Hz1/2 -20 --- 100 Detecctivity Temperature range Operation Measured at 1 Hz chopper frequency, within spectral range 5-14µm, using a blackbody radiator of 500K temperature. ▓ Thermopile voltage vs. blackbody temperature ▓ Frequency response ▓ Field of view ▓ Pin assignment & description 1 thermopile output pin (+) 3 thermopile output pin (-) Thermopile 2(R) 3(V-) 1(V+) 4(GND) BACKSIDE VIEW SIDE VIEW ▓ Order information : OTC-238-A A ▓ : 1 : standard filter (5-14µm) 2 : silicon filter with flat band transmission Transmission of filter Transmission of optical filter is measured by FTIR from 2µm ▓ Package The sensor is hermetically sealed into a TO-18 metal housing, with optical filter. This standard filter allows measurements to be made in the spectral range above 5µm wavelength. The dimensions of header and cap are shown below. Unit: mm 4.7000 CHIP CAP 3.6 HEADER 2.0 3.0000 WINDOW IR FILTER 0.43 ▓ Application circuit Circuit 1 : +5V C1 R1 Thermopile R4 + R2 1 C3 R5 3 2 4 Vout + OP R6 C6 C4 C5 Reference Resistor R3 C2 Circuit 2 : Ambient Temperature Compensation Circuit Pre-Amplification Circuit +5V R10 + A2 Thermopile (+) - +5V Adder C1 C3 + A1 - Thermopile (-) R13 R11 1 + 3 - R1 R2 Vout R7 2 4 + A3 - R8 C2 reference resistor R9 R12 C4