Datasheet SFM3003 series Digital Mass Flow Meter Product Summary Sensirion’s SFM3003 is a versatile, low pressure drop, bidirectional flow meter. Based on the same form factor as the proven SFM3000 series, SFM3003 comes with a larger flow range of up to 300slm and offers additional features for measuring flows of air, oxygen and mixtures of air and oxygen. SFM3003 series is the ideal choice for medical and industrial applications. Key characteristics at a glance Benefits of Sensirion’s CMOSens ® Technology High reliability and long-term stability Calibrated for O2, air and mixtures thereof Low pressure drop across the sensor Best signal-to-noise ratio Industry-proven technology with a track record of more than 15 years Designed for mass production High process capability Scalability

1. Ordering Information Use the part names and item numbers shown in the following table when ordering the SFM3003. For the latest product information and local distributors, visit www.sensirion.com. Part name Order number -30 to 300 slm range, with cap, low pressure drop (only one mesh at inlet) -150 to 300 slm range, with cap, extended negative flow range 2. Specifications Flow Specification1 Parameter Measurement Zero point Zero point Span shift due to temperature variation Flow step response time (τ63) Resolution Calibrated for Media compatibility Pressure Drop @60slm @200slm @300slm Air,...

Measurement range Accuracy Repeatability Electrical Specifications Parameter 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 Update rate flow value Update rate temperature value 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 The measured temperature is the temperature of the bulk silicon...

Mechanical Specifications Parameter Operating pressure range Allowable overpressure Rated burst pressure Materials Parameter Wetted materials PPE+PS blend, Si, glass (Si3N4, SiOx), gold, FR4, copper alloy, lead-free solder, epoxy, polyurethane, stainless steel (annealed) REACH, RoHS REACH and RoHS compliant Absolute Minimum and Maximum Ratings Parameter Storage temperature range 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 Pin Assignment The pin assignments of the SFM3003 series can be found in Table...

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...

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. I2C Address The I2C address for different SFM3003 versions are: Product Version Table 2: I2C addresses...

I2C Commands 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 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 4: Consecutive reads after I²C command to start continuous measurement. The flow and temperature values are raw data value consisting of a 16bit signed integer. For conversion into physical units refer to Section 4.5. Status Word The status word is returned along with every flow and temperature measurement....

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...