SENSIRION SCD43 Manual

Breaking the size barrier in optical co2 sensing

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SCD4x
Breaking the size barrier in optical CO
Features
Photoacoustic NDIR sensor technology PASens®
Small form factor: 10.1 x 10.1 x 6.5 mm
Reflow solderable for cost-effective assembly
Digital I
C interface
2
Integrated temperature and humidity sensor
Product Summary
The SCD4x is Sensirion's second generation series of
optical CO
sensors. The sensor series builds on the
2
photoacoustic NDIR sensing principle and Sensirion's
patented PASens® and CMOSens® technology to offer
high accuracy at an attractive price and small form factor.
SMD assembly allows cost- and space-effective
integration of the sensor combined with maximal freedom
of design. On-chip signal compensation is realized with
the built-in SHT4x humidity and temperature sensor.
Product Overview
Products
Details
SCD40-D-R2 Base accuracy, specified range
400 – 2'000 ppm
SCD41-D-R2 Improved accuracy, specified range
400 – 5'000 ppm, single shot operation
feature
SCD43-D-R2 High accuracy, specified range
400 – 5'000 ppm, comprehensive building
standard compatibility, single shot
operation feature
1 2 3 4
1
WELL v2, Q4 2024
2
2022 California Building Energy Efficiency Standards for Residential and Nonresidential Buildings
3
RESET Air Standard v2.0 Grade B
4
ASHRAE 62.1-2022 incl. Addendum d
www.sensirion.com
sensing
2
Product Variants
SCD40: Base accuracy, specified measurement range
400 – 2'000 ppm, compatible with WELL Building
3
Standard™
SCD41: Improved accuracy, specified measurement
range 400 – 5'000 ppm, additionally compatible with
California Title 24
operation mode
SCD43: High accuracy, specified measurement range
400 – 5'000 ppm, additionally compatible with
ASHRAE Standard 62.1
operation mode
CO
is a key indicator for indoor air quality (IAQ), as high
2
levels compromise human cognitive performance, sleep
quality, well-being and can be an indicator for increased
airborne disease transmission risk. The SCD4x enables
smart ventilation and air conditioning to help improve
energy efficiency and human comfort. Moreover, indoor
air quality monitors and other connected devices based
on the SCD4x can help maintain low CO
for a healthy, productive environment.
Functional Block Diagram
Version 1.7 – April 2025
1
and RESET
, features single-shot
2
® 3
, features single-shot
4
concentrations
2
1/30

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Summary of Contents for SENSIRION SCD43

  • Page 1 ASHRAE Standard 62.1 , features single-shot operation mode Product Summary The SCD4x is Sensirion’s second generation series of is a key indicator for indoor air quality (IAQ), as high optical CO sensors. The sensor series builds on the levels compromise human cognitive performance, sleep photoacoustic NDIR sensing principle and Sensirion’s...
  • Page 2: Table Of Contents

    Land Pattern Recommendation ......................... 24 Tape & Reel Package..........................25 Moisture Sensitivity Level .......................... 25 Soldering Instructions ..........................26 Traceability and Identification ........................26 Ordering Information ............................27 Historical Information ..........................27 Revision History .............................. 28 www.sensirion.com Version 1.7 – April 2025 2/30...
  • Page 3: Sensor Performance

    400 ppm. Maximum additional accuracy drift per year starting after five years estimated from stress tests is ±(5 ppm + 2% of reading). Stronger drift may occur if the sensor is not handled according to its handling instructions. www.sensirion.com Version 1.7 – April 2025...
  • Page 4: Specifications

    For proper function of the ASC field-calibration algorithm with default parameters, SCD4x must be exposed to air with CO concentrations at 400 ppm on a weekly basis. Sensor tested over simulated lifetime of >10 years for an indoor environment mission profile. www.sensirion.com Version 1.7 – April 2025 4/30...
  • Page 5: Interface Specifications

    ). Note that pull-up resistors may be included in the I/O circuits of microcontrollers. Figure 1: Typical application circuit (representative and not to scale). NXP I2C-bus specification and user manual UM10204, Rev.6, 4 April 2014 www.sensirion.com Version 1.7 – April 2025 5/30...
  • Page 6: Timing Specifications

    SCL clock frequency Table 7: System timing specifications. 2.5 Material Contents The device is fully REACH and RoHS compliant. Timing specifications based on the NXP I2C-bus specification and user manual UM10204, Rev.6, 4 April 2014 www.sensirion.com Version 1.7 – April 2025 6/30...
  • Page 7: Digital Interface Description

    ACK bit from the sensor, it is required to wait for the command execution time (see Table 9) before issuing the read header. If a command execution time is specified in Table 9 , further commands must not be sent during that command’s execution time. www.sensirion.com Version 1.7 – April 2025...
  • Page 8: Scd4X Command Overview

    0x244e write get_automatic_self_calibration_standard_period 0x234b read Table 9: List of SCD4x sensor commands. The rightmost column (‘During meas.’) indicates whether the command can be executed while a periodic measurement mode is running. www.sensirion.com Version 1.7 – April 2025 8/30...
  • Page 9: Basic Commands

    0x01f4 0x33 0x6667 0xa2 0x5eb9 0x3c (hexadecimal) = 500 ppm CRC of 0x01f4 Temp. = 25 °C CRC of 0x6667 RH = 37% CRC of 0x5eb9 Table 11: read_measurement I C sequence description www.sensirion.com Version 1.7 – April 2025 9/30...
  • Page 10: On-Chip Output Signal Compensation

    �������� [ 0 ] = �� [°��] ∗ ������������ Example: set temperature offset to 5.4 °C Write 0x241d 0x07e6 0x48 (hexadecimal) Command = 5.4 °C CRC of 0x7e6 offset Table 13: set_temperature_offset I C sequence description www.sensirion.com Version 1.7 – April 2025 10/30...
  • Page 11 Example: sensor altitude is 1’100 m Write 0x2322 (hexadecimal) Command Wait 1 ms command execution time Response 0x044c 0x42 (hexadecimal) Sensor altitude = 1’100 m CRC of 0x044c Table 16: get_sensor_altitude I C sequence description www.sensirion.com Version 1.7 – April 2025 11/30...
  • Page 12 Example: ambient pressure is 98’700 Pa Write 0xe000 (hexadecimal) Command Wait 1 ms command execution time Response 0x03db 0x42 (hexadecimal) Ambient P = 98’700 Pa CRC of 0x03db Table 18: get_ambient_pressure I C sequence description www.sensirion.com Version 1.7 – April 2025 12/30...
  • Page 13: Field Calibration

    0xb4 (hexadecimal) Command Input: 480 ppm CRC of 0x01e0 Wait 400 ms command execution time Response 0x7fce 0x7b (hexadecimal) Response: - 50 ppm CRC of 0x7fce Table 19: perform_forced_recalibration I C sequence description www.sensirion.com Version 1.7 – April 2025 13/30...
  • Page 14 = ASC target [ppm CO Example: Set ASC target to 435 ppm Write 0x243a 0x01b3 0x99 (hexadecimal) Command ASC target = 435 ppm CRC of 0x01b3 Table 22: set_automatic_self_calibration_target I C sequence description www.sensirion.com Version 1.7 – April 2025 14/30...
  • Page 15: Low Power Periodic Measurement Mode

    Max. command (hexadecimal) duration [ms] length [bytes] signal conversion length [bytes] signal conversion 0x21ac not applicable Example: start low power periodic measurement Write 0x21ac (hexadecimal) Command Table 24: start_low_power_periodic_measurement I C sequence description www.sensirion.com Version 1.7 – April 2025 15/30...
  • Page 16: Advanced Features

    Input parameter: - Response parameter: - Write Max. command (hexadecimal) duration [ms] length [bytes] signal conversion length [bytes] signal conversion 0x3615 Example: persist settings Write 0x3615 (hexadecimal) Command Table 26: persist_settings I C sequence description www.sensirion.com Version 1.7 – April 2025 16/30...
  • Page 17 Response parameter: - Write Max. command (hexadecimal) duration [ms] length [bytes] signal conversion length [bytes] signal conversion 0x3632 1’200 Example: perform factory reset Write 0x3632 (hexadecimal) Command Table 29: perform_factory_reset I C sequence description www.sensirion.com Version 1.7 – April 2025 17/30...
  • Page 18 CRC of 0x0440 Example: sensor variant is SCD43. Response bits 0…11 may differ from this example Response 0x5441 0xE9 (hexadecimal) Product version = SCD43 CRC of 0x5441 Table 31: get_sensor_variant I C sequence description www.sensirion.com Version 1.7 – April 2025 18/30...
  • Page 19: Single Shot Measurement Mode (Scd41 & Scd43 Only)

    Write 0x219d (hexadecimal) Command Table 32: measure_single_shot I C sequence description More information on ASC settings and SCD4x low power modes can be found in the application note on “Low Power Operation SCD4x” www.sensirion.com Version 1.7 – April 2025 19/30...
  • Page 20 Response parameter: - Write Max. command (hexadecimal) duration [ms] length [bytes] signal conversion length [bytes] signal conversion 0x36f6 Example: wake up the sensor Write 0x36f6 (hexadecimal) Command Table 35: wake_up I C sequence description www.sensirion.com Version 1.7 – April 2025 20/30...
  • Page 21 Example: read ASC initial period of 76 hours Write 0x2340 (hexadecimal) Command command execution time Wait 1 ms Response 0x004c 0xc1 (hexadecimal) 76 hours CRC of 0x004c Table 37: get_automatic_self_calibration_initial_period I C sequence description www.sensirion.com Version 1.7 – April 2025 21/30...
  • Page 22 Example: read ASC standard period of 156 hours Write 0x234b (hexadecimal) Command Wait 1 ms command execution time Response 0x009c 0xc5 (hexadecimal) Standard period CRC of 0x009c 156 hours Table 39: get_automatic_self_calibration_standard_period I C sequence description www.sensirion.com Version 1.7 – April 2025 22/30...
  • Page 23: Checksum Calculation

    > 0; --crc_bit) { (crc & 0x80) Final XOR 0x00 (crc << 1) ^ CRC8_POLYNOMIAL; Examples CRC (0xbeef) = 0x92 else (crc << 1); return crc; Table 40: I C CRC properties www.sensirion.com Version 1.7 – April 2025 23/30...
  • Page 24: Mechanical Specifications

    In any case, the keep-free area around the thermal relief hole of the sensor must be respected. Figure 4: Recommended SCD4x footprint (top view): landing pads (a), solder paste (b) and solder mask (c). All dimensions in millimeters. www.sensirion.com Version 1.7 – April 2025 24/30...
  • Page 25: Tape & Reel Package

    4.4 Moisture Sensitivity Level Sensirion SCD4x sensors must be treated according to Moisture Sensitivity Level 1 (MSL1) as per IPC/JEDEC J-STD-033B1. The manufacturing floor time (out of bag) at the customer’s end is not limited under normal factory conditions (≤30 °C and 85 %RH).
  • Page 26: Soldering Instructions

    All SCD4x sensors have a distinct electronic serial number for identification and traceability (see Section 3.10.2). The serial number can be decoded by Sensirion only and allows for tracking through production, calibration, and testing. All SCD4x sensors include a laser marking on the sidewall of the sensor cap. The laser marking contains the product variant (i.e., SCD40, SCD41 or SCD43) and the product serial number within a data matrix (Figure 6).
  • Page 27: Ordering Information

    Ordering Information Use the part names and product numbers shown in Table 42 when ordering the SCD4x CO sensor. For the latest product information and local distributors, please visit the Sensirion website. Part Name Description Ordering quantity (pcs) Product Number...
  • Page 28: Revision History

    RH/T response time specification and moved previous footnote #5 into prose text (Sections 1.2 and 1.3), clarification of footnotes #6-8(prev. footnotes 2-4). Changed moisture sensitivity level specification to MSL Level 1 (Section 2.2, Table 5) Clarification of footnote #15 (prev. footnote 12) www.sensirion.com Version 1.7 – April 2025 28/30...
  • Page 29 #1-3, Addition of new footnote #4 Clarified section on ASC functionality (Section 3.8), Added note on pressure/altitude compensation for conducting FRC (Section 3.8.1) Addition of specifications for SCD43 Minor editorial revisions and clarifications www.sensirion.com Version 1.7 – April 2025 29/30...
  • Page 30: Important Notices

    Warranty SENSIRION solely warrants to the original purchaser of this product for a period of 12 months (one year) from the date of delivery that this product is of the quality, material and workmanship defined in SENSIRION’s published specifications of the product. Within such period, if proven to be defective, SENSIRION shall as sole and exclusive remedy, in SENSIRION’s discretion, repair this product or send a replacement product, free of...

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