Sensirion SFM3505 High-Performance Digital Mass Flow Meters

Sensirion SFM3505 High-Performance Digital Mass Flow Meters are compact gas flow sensors that deliver ultra-low noise, exceptional accuracy, and minimal pressure drop within a small form factor. Building on the success of the SFM3119 and SFM3100, the SFM3505 introduces a completely redesigned architecture to achieve best-in-class performance with minimal resistance. The series is available in two variants: the SFM3505-300 standard accuracy variant and the SFM3505-300-X high accuracy variant.

Powered by Sensirion’s 5th-generation CMOSens^® Technology, the SFM3505 integrates the sensing element and advanced signal processing on a single microchip. This design ensures fast, stable, and fully calibrated digital output via a standard I²C interface. Engineered for long-term use, the sensor requires no additional calibration during production or in the field, thanks to the outstanding stability of CMOSens chips.

Calibrated for air and oxygen, the SFM3505 includes on-chip temperature compensation for precise measurements under varying conditions. These flow meters are the ideal solution for inspiratory flow measurement in applications such as mechanical ventilation, anesthesia, and gas mixing systems.

Features

Built on 5th-generation CMOSens technology
sensor element and advanced signal processing on a single microchip
Calibrated for air and oxygen
High accuracy
Low noise
Low pressure drop
Reduced dependency to inlet conditions

I²C interface
On-chip temperature compensation
No additional calibration needed
Compact dimensions
White O-rings produced according to ISO3601 class B, 16.1mm inner diameter, 1.6mm wire diameter
RoHS and REACH compliant

Applications

Mechanical ventilation
Anesthesia

Gas mixing systems
High accuracy and high flow applications

Specifications

-150slm to 300slm air and O₂ flow range
Sensor output
- Air flow
- O₂ flow
Maximum accuracy
- ±3% m.v. span, ±0.05slm offset for the SFM3505-300
- ±2% m.v. span, ±0.05slm offset for the SFM3505-300
Maximum noise
- 1% m.v. span
- 0.01slm offset
±(0.03slm or 0.5%) per 10°C from 25°C accuracy derating with temperature within -20°C to +85°C
Typical pressure dependence
- -1.5% at 525hPA (abs.)
- -0.5% at 750hPA (abs.)
- +0.7% at 1400hPA (abs.)
- +1.0% at 1650hPA (abs.)
Maximum pressure drop
- 85Pa at 60slm
- 200Pa at 100slm
- 750Pa at 200slm
3ms flow step response time
0.00004slm resolution (24-bit)
Supply voltage range
- 3.2V to 3.4V working
- -0.3V minimum to 5.5V maximum absolute

2.5V maximum power-up level
1.5V minimum power-down level
Maximum supply current
- 10mA measuring
- 0.6mA idle state
3mA minimum SCL and SDA sink current capability
0.05mA maximum DRDY driving strength
4kΩ typical DRDY internal resistance
2ms maximum power-up and soft reset time
4ms maximum time for the first flow output available
50ms maximum warm-up time
1000kHz maximum I²C SCL frequency
3880Hz to 4120Hz internal flow rate sampling rate range
650hPa gauge maximum operating/allowed overpressure
1250hPa gauge maximum burst overpressure
-20°C to +85°C operating temperature range
Non-condensing operating humidity
2kV maximum ESD rating, human body model (HBM) tested on IC chip level
Media compatibility
- Compatible gases - Air, N₂, O₂, other non-aggressive gases (non-condensing)
- Wetted materials - PPE+PS blend, Si, glass (Si3N4, SiOx), epoxy, FKM, typically non-wetted; gold, FR4, lead-free solder