Datasheet SFM3019 seriesDigital Mass Flow MeterProduct Summary SFM3019 is Sensirion's solution on providing high volumes of flow meters for medical ventilators in order to support the global pandemic situation due to the Corona virus outbreak. It relies on a modular approach of assembling approved parts with good availability to Sensirion and a high-volume through-put manufacturing. The housing geometry is based on the SFM3000 flow meter; hence it remains mechanically compatible to the SFM3000. A flow range from -10slm to +240slm and one directional flow supports high flow applications while still allowing to detect back flows. To minimize pressure-drop the SFM3019 is equipped with one mesh at the inlet. Key characteristics at a glance ■ Flow range up to 240slm ■ Calibrated for O2, air and mixtures thereof ■ Low pressure drop across the sensor Benefits of Sensirion’s CMOSens® Technology ■ Scalability ■ High reliability and long-term stability ■ Best signal-to-noise ratio ■ Industry-proven technology with a track record of more than 15 years ■ Designed for mass production ■ High process capability

Use the part names and item numbers shown in the following table when ordering the SFM3019. For the latest product information and local distributors, visit www.sensirion.com. Unless otherwise noted, all sensor specifications are valid at 25°C with VDD = 3.3 V and absolute pressure = 966 mbar. For other ranges contact Sensirion In standard liter per minute at 20°C and 1013 mbar for “Max” no sensor measured outside of these limits will be shipped and a CpK of 1.33 is targeted For “Typ” a CpK of 0.67 is targeted (95% of sensors within the Typ limit) Span or offset value, whichever is greater Measured...

The measured temperature is the temperature of the bulk silicon in the sensor. This temperature value is not only depending on the gas temperature, but also on the sensor’s surroundings. Using the signal to measure solely the gas temperature will need special precautions, such as isolating the sensor from external temperate influences.

The pin assignments of the SFM3019 series can be found in Table 1. The cap of the SFM3019 is compatible with DuraClik™ Wire-to-Board Receptacle Housing, Single Row, 4 Circuits. (Molex product number: 502351-0400). 1 For Air and N2. Long term exposure to (high concentrations of) O2 at high temperatures can reduce the product lifetime.

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 on status word see Section 4.3.2). 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...

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 time...

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 pull-up resistors to the bus voltage of the system. In the I2C protocol, a read or write bit follows the I2C address. The commands have a length of 16 bits. If commands require an argument,...

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 • Read Scale Factor, Offset, and Flow Unit • Soft reset • Entering and exiting sleep mode • Read product identifier The sensor measures both flow and temperature and in a third data buffer a status word. All three measurement results can be read out through one single I2C read header when the continuous measurement is running. The specific command code used...

Table 5: PC commands to update the concentration for binary gas mixtures.

After those two commands changing the gas concentration, measurement results can be read with a read header as described in Section 4.3.1. No new start command is required. Please note: • The concentration value must not be updated more than once per millisecond. • If a concentration value greater than 1000 is passed to the sensor, the measurement mode will stop. • For the initial concentration value, which is supplied with the start measurement command (0x3632, c.f. Sec. 4.3.1) the command argument will be immediately applied without a need to send the second command. Attention: Changing the...

This command provides the scale factor and offset to convert flow readings into physical units (see Section 4.5). The scale factor and offset are specific to the calibrated gas / gas mixture and its corresponding lookup table used for the flow measurement. Therefore, the gas / gas mixture needs to be specified in the command argument by the command code of the corresponding start continuous measurement (see Section 4.3.1). For the SFM3019, the flow unit is a fixed value 0x0148 and corresponds to slm: standard liter per minute at 20°C and 1013mbar pressure. Table 9: Reset command After the reset...