SFM3119 Low Pressure Drop Digital Flow Meter
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Datasheet – SFM3119 Low Pressure Drop Digital Flow Meter Product Summary The SFM3119 sensor is Sensirion’s flow meter designed for the mass flow measurement in ventilators. It measures the flow rate of air, oxygen and non-aggressive gases with superb accuracy. A special design of the flow channel results in the very low pressure drop through the flow body of the sensor making it extremely suitable for medical ventilation and respiratory applications. The outstanding performance of these sensors is based on Sensirion’s patented CMOSens® sensor technology, which combines a thermal sensor element, signal processing and digital calibration on a single microchip. This assures very fast signal processing. The well-proven CMOS technology is perfectly suited for high-quality mass production and is the ideal choice for demanding and cost-sensitive OEM applications. Benefits of Sensirion’s CMOSens® Technology High reliability and long-term stability Calibrated for O2, air and mixtures thereof Compact design Industry-proven technology with a track record of more than 15 years Designed for mass production Very fast response time High process capability Applications  Ventilation  Anesthesia  Inspiratory flow sensing  Gas mixing Sensor electronics The SFM3119 flow meter features a sixth-generation silicon sensor chip and provides a fully temperature compensated flow measurement. OEM options A variety of custom options can be implemented for highvolume OEM applications (digital interface, custom flow rates, calibration for other gases, different body form factor etc.). Contact us for more information.

1. Ordering Information Use the part names and item numbers shown in the following table when ordering the SFM3119. For the latest product information and local distributors, visit www.sensirion.com. Part name Order number -10 to 240slm range, with cap, low pressure drop Flow specifications 1 Parameter Flow Range span (< 100 slm) span (< 160 slm) span (< 240 slm) offset span (<85 slm) span (<160 slm) span (<240 slm) offset Span offset Accuracy Shift due to Temperature Variation6 Flow step response time (τ63) Resolution Pressure Drop Calibrated Temperature Range otherwise noted, all sensor...

Temperature Specification7 Parameter Measurement range Electrical Specifications Supply Voltage Power-up/down level Idle state Sleep mode Recommended: 3.3V +/- 5% (calibration voltage) Measuring Supply current Timing Specifications Parameter Power-up time Soft reset time Warm-up time I2C SCL frequency Update rate flow value Update rate temperature value Comments Time to sensor ready Time between soft reset command or exit sleep mode and sensor ready To reach accuracy spec after first measurement command Temperature value is updated at least every 16 flow values Mechanical Specifications...

Media compatibility Parameter Calibration Media Compatibility Wetted Materials RoHS, REACH Value Air, O2 and mixtures of Air/O2 Air, N2, O2, other non-aggressive gases (non-condensing) PPE+PS blend, Si, glass (Si3N4, SiOx), gold, FR4, copper alloy, lead-free solder, epoxy, polyurethane, stainless steel (annealed) RoHS and REACH compliant Absolute Minimum and Maximum Ratings Max. humidity for long term exposure ESD HBM (human body model) Supply Voltage VDD Max Voltage on pins (SDA, SCL) Input current on any pin Operating temperature range8 Storage temperature range The pin assignments of the...

3. Measurement Mode After the sensor receives a “start continuous measurement” command (for more details see Section 4.3.1) it enters the corresponding measurement mode and continuously performs a measurement every ~0.5ms. Therefore, a new reading can be obtained every 0.5ms. A single reading consists of three measurement values: flow, temperature, and one value for a status word (for more details see Section 4.3.1). Averaging of Flow Value Two modes for on-sensor averaging of the flow signal are available: 1) Average-until-read: in this mode, the sensor averages all measured values prior...

Sensor Start-Up and Warm-Up Behavior The typical time for system power-up (until the sensor responds to communication requests) is 2ms. The typical time from a soft reset until the sensor responds to communication requests is also 2ms if the SCL line is high. After reset or start-up of the sensor, the sensor’s internal heater is off and is automatically turned on by performing a Start Continuous Measurement command (see Section 4.3.1). The very first measurement after Start Continuous Measurement is ready after approximately 12ms. Due to the thermal measurement principle, a total warm-up...

4. Digital Interface Description The sensor’s digital interface is compatible with the I2C protocol. This chapter describes the available command set. For detailed information about the I2C protocol, please consult the document "NXP I2C-bus specification and user manual" (http://www.nxp.com/documents/user_manual/UM10204.pdf). The physical interface consists of two bus lines: a data line (SDA) and a clock line (SCL) which need to be connected via pullup resistors to the bus voltage of the system. The I2C address for SFM3119 in Hex is 0x29 and in binary, b 0101001. In the I2C protocol, a read...

The command set consists of a set of various commands, which are described in the following sections:         Various Start continuous measurement commands (one for each gas/gas mixture) Update concentration Stop continuous measurement command Configuration of averaging Read Scale Factor, Offset, and Flow Unit Soft reset Entering and exiting sleep mode Read product identifier 4.3.1 Start Continuous Measurement and Read Results The sensor measures both flow and temperature and provides in a third data buffer a status word. All three measurement results can be read out through one...

Preceding command Consecutive read Continuous measurement After a start continuous measurement command, the measurement results can be read out. The temperature and the consecutive bytes don’t need to be read out (every time). The read sequence can be aborted by a NACK and a STOP condition. Table 3: Consecutive reads after I²C command to start continuous measurement. The flow, and temperature values are raw data value consisting of a 16-bit signed integer. For conversion into physical units refer to sections 4.5 4.3.2 Status Word The status word is returned along with every flow and...