TGS 2612 pdf

Basic Measuring Circuit:The sensor requires two voltage inputs:heater voltage (VH) and circuit voltage(VC). The heater voltage (VH) is appliedto the integrated heater in order tomaintain the sensing element at aspecific temperature which is optimalfor sensing. Circuit voltage (VC) isapplied to allow measurement of voltage(VRL) across a load resistor (RL) which isconnected in series with the sensor.A common power supply circuit can beused for both VC and VH to fulfill thesensor's electrical requirements. Thevalue of the load resistor (RL) should bechosen to optimize the alarm thresholdvalue, keeping power dissipation (PS)of the semiconductor below a limit of15mW. Power dissipation (PS) will behighest when the value of Rs is equal toRL on exposure to gas.Specifications (tentative):Structure and Dimensions:ModelnumberTGS 2612Sensingelement typeD1Top viewStandardTargetpackagegasesTO-5 metal canMethane, propane, iso-butaneTypicalStandard circuitconditionsdetection range1~25%LEL of each gasHeaterVoltage VH 5 . 0± 0.2V DC/ACCircuitvoltage VC 5 . 0± 0.2V DC/ACPs≤ 15mWLoadresistance RL Variable0.45kΩ min.Sensingelementø9.2±0.2ø8.1±0.2Side viewHeaterresistance RH approx.59Ω at room temp.12.4±1.0Heatercurrent IH 56± 5mAElectricalcharacteristicsunder standard testconditionsStandard testconditionsREV: 07/04Heater powerconsumptionSensorresistanceSensitivity(change ratio of Rs)Cross sensitivity(corresponding with10%LEL methane)Test gas conditionsCircuit conditionsConditioningbefore testperiodThe value of power dissipation (PS) canbe calculated by utilizing the followingformula:(VC - VRL) 2PS =RSPHRs280mWVH = 5.0V DC0.68~6.8kΩ in 5000ppm methane0.50 ~ 0.65Rs (9000ppm)Rs (3000ppm)≤25%LELpropane≤25%LELiso-butaneMethane, propane, & iso-butanea t 20± 2 ˚C, 65± 5%RHVC = 5. 0± 0.01V DCVH = 5. 0± 0.05V DC7 daysin airSensor resistance (Rs) is calculated witha measured value of VRL by using thefollowing formula:RS =VC - VRLVRLx RL90˚ø0.55±0.0543123.6±0.110.0±1.03.6±0.1FIGARO ENGINEERING INC.1-5-11 Senba-nishiMino, Osaka 562 JAPANTel.: (81) 72-728-2561Fax: (81) 72-728-0467email: figaro@figaro.co.jpBottom viewø5.1