Design-In guidelines for SCD30
CO2, humidity, and temperature sensor
1Introduction

To ensure best performance of the sensor in end user device it is important that a few simple recommendations are consideredwhen designing a product using SCD30. This application note will give advice about how to design the product in order to ensure
optimal working conditions for best performance.

2Package

SCD30 consists of a PCB, an optical cavity including a light source and detectors to measure CO2 gas concentration, an SHT31
humidity and temperature sensor as well as read-out and data processing electronics. SHT31 sensor is mounted at the bottomside of SCD30 PCB. CO2 molecules can diffuse from bottom side and from top side into the cavity.
Top side

3Bottom side

Placement of the sensor

3.1 Coupling to Ambient
SCD30 interacts with the environment in order to sense the physical quantities CO2 concentration, humidity and temperature.
Therefore coupling SCD30 to ambient via the sensor openings and a suitable device design is from uttermost importance.
Ideally, the sensor is placed as close as possible to the device’s outer shell with a large opening allowing the sensor to be
exposed to the ambient. The larger the opening, the better the air exchange between the sensor’s direct surrounding and theambient resulting in faster response times.

To enable fastest response times the inner open volume of the device should be designed as small as possible. It is
recommended to mount SCD30 such that the bottom side of the sensor faces the host PCB, however SCD30 can also be
mounted upside down.

www.sensirion.com

D1 - Version 0.2 – February 2019

1/4

3.2 Decoupling from external heat sources
Sensirion SCD30 CO2 sensors are compensated for temperature for best performance and stability. The calibration assumes
that SCD30 is in thermal equilibrium with its environment and temperature gradients within the package only arise from SCD30’s
internal electrical components (e.g. the light source). Heat sources such as microcontrollers might therefore induce thermal
stress on SCD30 reducing the accuracy. To overcome related performance limitations the distance between SCD30 and heatsources should be as large as possible.

It is further recommended to place SCD30 below heat sources as air convection arising from heat sources might heat up thesensor.
Residual temperature rise of SCD30 will affect the humidity and temperature reading. SCD30 features an internal compensationengine to account for this sensor heat-up. Please see the interface description for details on how to activate and tune thecompensation engine.

3.3 Isolation from air flow
Pressure changes alter the number of CO2 molecules inside the optical cavity of SCD30. For this reason, the CO2 concentration
reading from SCD30 will change when the ambient pressure is changing. Air flow as present in e.g. ducts can generate pressure
drops, back pressure and dynamic fluctuations leading to increased sensor noise and reduced accuracy. Therefore, it isrecommended to isolate SCD30 from air flow as good as possible. This can be achieved by e.g. placing the sensor in theslipstream of a flow restriction or in a volume separated from the main air flow.

www.sensirion.com

D1 - Version 0.2 – February 2019

2/4

3.4 Protection from sun light
Exposing SCD30 to direct sun light might introduce temperature gradients and age SCD30 additionally. Thus it is recommended
to protect the sensor sun light. This can be achieved by a suitable design-in or by using a light shade.

www.sensirion.com

D1 - Version 0.2 – February 20193/4

Revision History
DateApril 2018
February 2019

Version
0.1
0.2

Page(s)all
all

Changes
Initial version
Removal Preliminary Watermark

Copyright © 2018 by SENSIRION
CMOSens® is a trademark of Sensirion
All rights reserved

1Sensirion AG
Laubisruetistr. 50
CH-8712 Staefa ZH
Switzerland

Sensirion Inc., USA
phone: +1 312 690 5858
info-us@sensirion.com
www.sensirion.com

Sensirion Korea Co. Ltd.
phone: +82 31 337 7700~3
info-kr@sensirion.com
www.sensirion.co.kr

phone: +41 44 306 40 00
fax:+41 44 306 40 30
info@sensirion.com
www.sensirion.com

Sensirion Japan Co. Ltd.
phone: +81 3 3444 4940
info-jp@sensirion.com
www.sensirion.co.jp

Sensirion China Co. Ltd.
phone: +86 755 8252 1501
info-cn@sensirion.com
www.sensirion.com.cn

Sensirion Taiwan Co. Ltd
phone: +886 3 5506701
info@sensirion.com
www.sensirion.com

To find your local representative, please visit
www.sensirion.com/distributors

2

www.sensirion.com

D1 - Version 0.2 – February 20194/4