Table 2: Additional sensor specifications.
Media Air, N
2 – for other gases contact Sensirion AG. Operating Conditions: - Temperature - Humidity -10 °C … +60 °C / 14°F … 140 °F non-condensing Ambient storage conditions
1 -40 °C … +80 °C / -40°F … 176 °F Position sensitivity below resolution Response time 40 ms (for faster response time contact Sensirion) Admissible overpressure (short term) 1 bar (14.5 PSI) Burst Pressure Capability 2 bar (29 PSI) Weight 14 g Protection Class IP 20 Wetted materials Glass (silicon nitride, silicon oxide), Silicon, PPS (Polyphenylene Sulfide), PEEK (Polyetheretherketone), FR4, Silicone as static sealing, Epoxy Gas flow through sensor see Figure 6. Lead free The SDP1000 family is fully RoHS compliant
(1) For maximum 2 weeks 1.1 Temperature Compensation
The SDP1000 / SDP2000 differential pressure sensors feature a sophisticated built-in temperature compensation circuit. The temperature is measured on the CMOSens chip by means of a PTAT bandgap reference temperature sensor specifications. Its data is fed into a compensation circuit which is also integrated on the CMOSens This leads to the following correction factors: Table 3: Altitude correction factors.
Altitude [meter] Ambient Pressure (P
amb ) [mbar] Correction Factor P
cal / P
amb 0 1013 0.95
® sensor chip. No external temperature compensation is therefore required.
250 984 0.98 425 966 1.00 500 958 1.01
1.2 Altitude Correction
750 925 1.04
The SDP1000 / SDP2000 differential pressure sensors achieve their unsurpassed performance by using a dynamic measurement principle, i.e. an applied differential pressure forces a small air flow through the sensor. This results in a dependence of the indicated differential pressure on the ambient air density. While the temperature effect is compensated (see Paragraph 1.1) the altitude above sea level has an influence on the SDP1000 / SDP2000 output. If desired, this effect can be compensated by a correction factor according to the following equation:
1500 842 1.15 2250 766 1.26 3000 697 1.38
Example: The SDP1000 is used at 750 m above sea level. The output of the SDP1000 shows 0.5 V, which corresponds to Dp
sensor = 33.3 Pa. Taking into account the correction factor P
cal / P
amb = 1.04 the effective differential pressure Dp
eff is 33.3 Pa * 1.04 = 34.6 Pa. Note: Dp
eff = Dp
sensor * P
cal / P
amb In many HVAC applications such as filter monitoring, fan/ventilator control or air flow measurement the described effect is actually welcome since at the end the mass flow and not volume flow is the effective value to control. where Dp
eff is the effective differential pressure, Dp
sensor the differential pressure indicated by the SDP1000 / SDP2000, P
cal the absolute pressure during calibration (966 mbar) and P
amb the actual ambient absolute pressure.
www.sensirion.com v 3.1 June 2008 3/10