968-007

ULPSM-Ethanol 968-007 October 2016 Ultra-Low Power Analog Sensor Module for Ethanol BENEFITS • • • • • • 0 to 3 V Analog Signal Output Low Power Consumption < 45 µW Fast Response On-board Temperature Sensor Easy Sensor Replacement Standard 8-pin connector APPLICATIONS • • • • Law Enforcement Breathalyzers Evidential Breath Alcohol Testing Portable Breath Alcohol Tester Personal Breathalyzers DESCRIPTION Quickly integrate Breath Alcohol or Ethanol Sensing into your system with very low power consumption and a simple analog sensor signal output. The ULPSM converts the Ethanol sensor’s linear current signal output to a linear voltage signal, while maintaining the sensor at its ideal biased operation settings. MEASUREMENT PERFORMANCE CHARACTERISTICS Measurement Range Lower Detection Limit Resolution Accuracy Response Time T90 Power-On Stabilization Time PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the SPEC Sensors standard warranty. Production processing does not necessarily include testing of all parameters. 0 to 200 ppm 0.2 ppm 0.2 ppm < ± 2 % of reading < 60 seconds 15 minutes recommended Copyright © 2011-2016, SPEC Sensors LLC ULPSM-Ethanol 968-007 October 2016 ABSOLUTE MAXIMUM RATINGS Parameter Supply Voltage Storage Temperature Storage Humidity Storage Pressure Storage Time Operating Temperature Operating Humidity Operating Temperature Operating Humidity Operating Pressure Conditions Vapor sealed @ 50% RH Non-condensing, Vapor sealed Vapor sealed Vapor sealed < 10 hours < 10 hours, Non-condensing Continuous Continuous, Non-condensing Continuous Min. Rec. Max. 3.3 30 80 1.2 50 100 40 95 1.2 V ̊C % RH atm. Months ̊C % RH ̊C % RH Atm. Min. Typ. Max. Units V 3.75 (V+/2 + 0.05) + 0.005 5.25 2.7 5 20 0.8 -40 0 -20 15 0.8 3 20 50 1 12 25 50 1 Units ELECTRICAL CHARACTERISTICS Parameter Supply Current Power Consumption Vref Conditions V+ = 3.0 V V+ = 3.0 V Vgas Zero Vgas Span (M) Room temperature PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the SPEC Sensors standard warranty. Production processing does not necessarily include testing of all parameters. 5 15 (V+/2 + 0.05) – 0.005 2.25 10 30 V+/2 + 0.05 (V+/2 + 0.05) 15 45 µA µW V mV/ppm Copyright © 2011-2016, SPEC Sensors LLC ULPSM-Ethanol 968-007 October 2016 CALCULATING GAS CONCENTRATION The target gas concentration is calculated by the following method: ∙ , where Cx is the gas concentration (ppm), Vgas is the voltage output gas signal (V), Vgas0 is the voltage output gas signal in a clean-air environment (free of analyte gas) and M is the sensor calibration factor (V/ppm). The value, M, is calculated by the following method: 10 10 , where the Sensitivity Code is provided on the sensor label and the TIA Gain is the gain of the trans-impedance amplifier (TIA) stage of the ULPSM circuit. Standard gain configurations are listed in the table below. The value Vgas0 can also be represented by: , where, Vref is the voltage output reference signal (V) and Voffset is a voltage offset factor. The Vref output acts as the reference voltage for zero concentration even as the battery voltage decreases. Measuring Vref in-situ compensates for variations in battery or supply voltage, minimizing these effects on Cx. A difference amplifier or instrumentation amplifier can be used to subtract Vref from Vgas. Alternatively, when measuring Vref directly, always use a unity gain buffer. Voffset, accounts for a small voltage offset that is caused by a normal sensor background current and circuit background voltage. To start, Voffset = 0 is an adequate approximation. To achieve higher-precision measurements, Voffset must be quantified. Once the sensor has been powered-on and allowed to stabilize in a clean-air environment (free of the analyte gas) and is providing a stable output within your application’s measurement goals, the value of Vgas may be stored as Vgas0 and used in subsequent calculations of gas concentration, Cx. Target Gas Carbon Monoxide Hydrogen Sulfide Nitrogen Dioxide Sulfur Dioxide Ozone Ethanol Indoor Air Quality Respiratory Irritants PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the SPEC Sensors standard warranty. Production processing does not necessarily include testing of all parameters. TIA Gain (kV/A) 100 49.9 499 100 499 249 100 499 Copyright © 2011-2016, SPEC Sensors LLC ULPSM-Ethanol 968-007 October 2016 TEMPERATURE COMPENSATION Temperature fluctuations have a predictable, easily compensated effect on the sensor signal. The figures below show the typical Temperature dependency of the output and baseline of 3SP-Ethanol-1000 sensors under constant humidity of 40-50% RH. This is a very uniform and repeatable effect, easily compensated for in hardware or software. From the graphs above:   The temperature effect of zero shift is expressed as ppm change. The temperature effect of span (sensitivity) is expressed with respect to sensitivity at the calibration temperature of 20 °C. When implementing temperature compensation, first correct the temperature effect on the zero (offset) and then correct the temperature effect on the span (sensitivity) of the sensor. These corrections can be done in software by implementing one of the following:    Curve fit Look up table A set of linear approximations, as outlined in the following table. Temperature Coefficient of Span (%/°C) (Typical) Temperature Coefficient of Zero Shift (ppm/°C) (Typical) PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the SPEC Sensors standard warranty. Production processing does not necessarily include testing of all parameters. -20 °C to 20 °C -0.8%/°C 20 °C to 40 °C 0.25%/°C -20 °C to 0 °C 0.02 ppm/°C 0 °C to 25 °C 0.14 ppm/°C 25 °C to 40 °C 0.75 ppm/°C Copyright © 2011-2016, SPEC Sensors LLC ULPSM-Ethanol 968-007 October 2016 CROSS SENSITIVITY Most chemical sensors exhibit some cross-sensitivity to other gases. The following table lists the relative response of common potential interfering gases, and the concentration at which the data was gathered. Gas/Vapor Ethanol Carbon Monoxide Hydrogen Sulfide Nitric Oxide Sulfur Dioxide Chlorine n-Heptane Methane Ozone Nitrogen Dioxide Ammonia Applied Concentration (PPM) 200 400 25 50 20 10 500 500 5 10 100 Typical Response (PPM Ethanol)) 200 251 63 54 12 -14 -13