SDP2108-R Datasheet SDP2108-R | P1-P3

www.sensirion.com Version 2 – February 2013

1/7

SDP1108/SDP2108

Low Differential Pressure Sensor

with fast response time

− For medical ventilators (ICU and home care)

− High sensitivity below 10 Pa to measure small volume flow (neonatal)

− Fast response time for efficient trigger function

− Unsurpassed performance thanks to CMOSens

technology

− Offset and hysteresis free

− Fully calibrated and temperature compensated

− Not sensitive to the mounting orientation and vibrations

SDPx108 Product Summary

The SDPx108 sensor family is a differential pressure

sensor for air based on the successful SDP1000/

SDP2000 sensor from Sensirion AG. The response time

of the SDPx108 has been optimized for medical

ventilation applications.

Mounted in a rugged, chemically inert PPS housing the

SDPx108 differential pressure sensors feature a unique

dynamic range, zero offset and unsurpassed long term

stability. This makes it an ideal fit for demanding yet cost

sensitive OEM applications in medical and HVAC

equipment.

The SDPx108 is fully RoHS compliant.

The SDPx108 is supplied with 5.0 V and provides a

0.25…4.0 V output. Although the output of the sensor is

analog, the internal linearization and temperature

compensation is performed digitally. This results in a

superior accuracy, outstanding resolution (up to 0.05 Pa),

and lowest temperature dependence.

Its leading performance is based on Sensirion’s proprietary

CMOSens

sensor technology which combines the sensor

element with amplification and A/D conversion on one

single silicon chip. The differential pressure is measured by

a thermal sensing element. In contrast to other thermal

differential pressure sensors only a very small amount of

air is required. This leads to a reliable operation even

under harsh conditions. In comparison to membrane and

piezo-resistive based sensors the SDPx108 differential

pressure sensors show an extended measurement range,

better offset stability and improved reproducibility even at

lowest pressure ranges. In addition the SDPx108 is robust

against pressure bursts and shows no sensitivity to the

mounting orientation.

Applications

Medical applications:

• Homecare ventilation

• Intensive care ventilation (ICU)

• Other

Block Diagram

Differential

pressure

Sensor

CMOSens

SENSOR CHIP

DIGITAL

Linearization and

Temperature

compensation

A/D converter

Memory

D/A

converter

Pin 1:

5.0 V

Pin 3: OUT

0.25 V to 4 V

Pin 2:

GND

www.sensirion.com Version 2- February 2013 2/7

1 Sensor Output Characteristics

SDPx108-R

0.25

0.75

1.25

1.75

2.25

2.75

3.25

3.75

0 20 40 60 80 100

differential pressure [% FS]

output voltage [V]

The SDPx108-R provides a fully calibrated voltage

output. To enhance resolution and accuracy at very

low differential pressures, the SDPx108 standard

version (SDPx108-R) comes with a root-square

output characteristics.

For high-quantity OEM applications, other ranges

and output characteristics can be realized. E.g.

linear output and a bidirectional measurement

range is possible. Please contact Sensirion for

further information.

[ ]

PaFS

VVoltageOutput

Pa ⋅













−

75.3

25.0_

][Press. Diff.

Use this formula to convert the sensor output into

physical value.

Calibration conditions apply unless otherwise noted: 23°C and p

absolute

= 966 mbar, dry air, V

= 5.000 V. FS is 500Pa for the SDP1108 and

3500 Pa for the SDP2108.

2 Specifications

Table 1: SDPx108-R Sensor specifications

Parameter

SDP1108-R SDP2108-R Unit

Min Typ Max Min Typ Max

Measurement range

0.25 - 4 0.25 4 Volts

0 - 500 0 3500 Pa

0 - 2 0 14 Inch water

Accuracy

20% FS to 100% FS - 1.0 2.0 - 1 2 % Measured Value

0 to 20% FS - 0.2 0.4 - 0.2 0.4 % Full Span

zero

0.01

0.06

0.1

0.6

Repeatability

100 to 500 Pa - 0.3 1.0 - 0.3 1.0 % Measured Value

0 to 100 Pa - 0.05 0.2 - 0.06 0.2 % Full Span

Null drift per year

- 0 0.1 - 0 0.3 Pa / year

Additional error over

temperature

(T ≠ 23°C)

0 to 100 % FS - 0.03 0.05 - 0.03 0.05 % Measured Value

/ °C

zero - 1 2 - 1 3 mV/°C

Response time

(8)

6.6 8.0 10.1 6.6 8.0 10.1 ms

Cut off frequency of internal filter 17 20 24 17 20 24 Hz

Calibration conditions apply unless otherwise noted: 23°C and p

absolute

= 966 mbar, dry air, V

= 5.000 V

Variance between the zero point (offset) of different sensors measured under the same conditions (e.g. same supply voltage, temperature, …)

Include deviations due to linearity, hysteresis, and repeatability

% Measured value = (SDPx108 output [Pa] - output of reference instrument [Pa]) / output of reference instrument [Pa].

Full span is defined as 3750 mV / 500 Pa for SDP1108 and 3750 mV / 3500 Pa for the SDP2108.

Drift over time due to aging, pressure cycles… Test results can be provided.

The additional error due to temperature variation is temporary. Once the sensor is back to the calibration temperature, the shift disappears

(no hysteresis).

Tau= 0 to 63%, filter response time = 8ms. For faster response time, contact Sensirion.

www.sensirion.com Version 2 – February 2013 3/7

Table 2: Additional sensor specifications.

Parameter

Media Calibration

Air, N

– for other gases contact Sensirion AG.

Media Compatibility Air, N

, O

Operating Conditions

- Temperature

- Humidity

-10 °C … +60 °C / 14°F … 140 °F

non-condensing

Ambient storage conditions

-40 °C … +80 °C / -40°F … 176 °F

Orientation sensitivity below zero point accuracy

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, Gold

Electromagnetic compatibility EN 61000-4-2 Air discharge (ESD)

± 2 kV

Lead free ROHS compliant.

Sensors are calibrated for a specific gas, please contact Sensirion when you employ different gases than the specified.

Condensation of liquids or dust on the sensor membrane might lead to sensor offset. Please consult our application notes on www.sensirion.com.

For maximum 2 weeks

2.1 Temperature Compensation

The SDPx108 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. Its data is fed into a compensation circuit which

is also integrated on the CMOSens

sensor chip. No

external temperature compensation is therefore required.

2.2 Altitude Correction

The SDPx108 differential pressure transducers achieve

their unsurpassed performance by using a dynamic

measurement principle: An applied differential pressure

forces a small air flow through the SDPx108, which

measures this air flow.

The sensor signal is dependant on the ambient air

density. The temperature effect on density is

compensated by internal intelligence (see Paragraph

2.3). Effects on density due to a change of ambient

pressure, typically a change of altitude above sea level,

can be compensated using a correction factor according

to the following equation:

eff

= Dp

sensor

cal

/ P

amb

Where Dp

eff

is the effective differential pressure, Dp

sensor

the differential pressure indicated by the SDPx108, P

cal

the absolute pressure during calibration (966 mbar) and

amb

the actual ambient absolute pressure.

This leads to the following correction factors:

Table 3: Altitude correction factors.

Altitude

[meter]

Ambient Pressure

amb

) [mbar]

Correction Factor

cal

/ P

amb

1013

0.95

250

984

0.98

425

966

1.00

500

958

1.01

750

925

1.04

1500

842

1.15

2250

766

1.26

3000

697

1.38

Example:

The SDP1108 is used at 750 m above sea level. The

output of the SDP1108 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:

In many medical and 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.

P1-P3 P4-P6 P7-P7

SDP2108-R

Mfr. #:

Buy SDP2108-R

Manufacturer:

Sensirion

Description:

Board Mount Pressure Sensors Differ Pressure Sensor

Lifecycle:

New from this manufacturer.

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Products related to this Datasheet

SDP2108-R