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SCD42
Breaking the size barrier in CO
Features
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Photoacoustic sensor technology PASens®
Smallest form factor: 10.1 x 10.1 x 6.5 mm
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Reflow solderable for cost effective assembly
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Large output range: 0 ppm – 40'000 ppm
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Product Summary
The SCD42 is Sensirion's next generation miniature CO
sensor. This sensor builds on the photoacoustic sensing
principle and Sensirion's patented PAsens® and
CMOSens® technology to offer high accuracy at an
unmatched price and smallest 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 build-in SHT4x humidity
and temperature sensor.
Device Overview
Products
Details
SCD42-D-R2 Accuracy: ± 75 ppm @ 400 – 1'000 ppm
Full product list on page 20
www.sensirion.com
sensing
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CO
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compromise humans' cognitive performance and well-
being. The SCD42 enables smart ventilation systems to
regulate ventilation in the most energy-efficient and
human-friendly way. Moreover, indoor air quality monitors
and other connected devices based on the SCD42 can
help maintaining low CO
productive environment.
Functional Block Diagram
Preliminary Version 0.92 – October 2021
Large supply voltage range: 2.4 – 5.5 V
Accuracy: ± 75 ppm @ 400 ppm – 1'000 ppm
Digital I
C interface
2
Integrated temperature and humidity sensor
is a key indicator for indoor air quality as high levels
concentration for a healthy,
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Table of Contents
Related Manuals for SENSIRION SCD42
Summary of Contents for SENSIRION SCD42
- Page 1 SHT4x humidity productive environment. and temperature sensor. Functional Block Diagram Device Overview Products Details SCD42-D-R2 Accuracy: ± 75 ppm @ 400 – 1’000 ppm Full product list on page 20 www.sensirion.com Preliminary Version 0.92 – October 2021 1/21...
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Page 2: Table Of Contents
Digital Interface Description ..........................7 Power-Up and Communication Start ......................7 Data type & length ............................7 Command Sequence Types ........................7 SCD42 Command Overview ........................8 Basic Commands ............................9 On-Chip Output Signal Compensation ...................... 10 Field Calibration ............................13 Advanced Features ........................... -
Page 3: Sensor Performance
± (5 ppm + 2 % of reading). Higher drift values may occur if the sensor is not handled according to its handling instructions. Design-in of the SCD42 in final application, self-heating of the sensor and the environment impacts the accuracy of the RH/T sensor. To realize indicated specifications, the temperature-offset of the SCD42 inside the customer device must be set correctly (see chapter 3.6). -
Page 4: Specifications
Short term storage refers to temporary conditions during e.g. transport. For proper function of ASC field-calibration algorithm the SCD42 has to be exposed to clean air with 400 ppm CO concentration regularly. Sensor tested over simulated lifetime of > 10 years for indoor environment mission profile www.sensirion.com... -
Page 5: Interface Specifications
2.3 Interface Specifications The SCD42 comes in an LGA package (Table 6). The package outline is schematically displayed in chapter 4.1. The landing pattern of the SCD42 can be found in chapter 4.2. Name Comments Supply voltage Supply voltage IR source, must... -
Page 6: Timing Specifications
2.4 Timing Specifications Table 7 list the timings of the ASIC part and does not reflect the availability or usefulness of the sensor readings. The SCD42 supports the I C “standard-mode” as is described elsewhere (see footnote Parameter Condition Min. -
Page 7: Digital Interface Description
Digital Interface Description All SCD42 commands and data are mapped to a 16-bit address space. SCD42 Hex. Code C address 0x62 Table 8 I C device address. 3.1 Power-Up and Communication Start The sensor starts powering-up after reaching the power-up threshold voltage V = 2.25 V. -
Page 8: Scd42 Command Overview
3.4 SCD42 Command Overview Table 9: List of SCD42 sensor commands. Detailed description of SCD42 commands can be found further down. *Column indicates whether command can be executed while a periodic measurement is running. Domain Command Hex. C sequence type... -
Page 9: Basic Commands
3.5 Basic Commands This section lists the basic SCD42 commands that are necessary to start a periodic measurement and subsequently read out the sensor outputs. The typical communication sequence between the I C master (e.g., a microcontroller) and the SCD42 sensor is as follows: 1. -
Page 10: On-Chip Output Signal Compensation
Note that the temperature offset does not impact the accuracy of the CO output. To change or read sensor settings, the SCD42 must be in idle mode. A typical sequence between the I C master and the SCD42 is described as follows: 1. - Page 11 Description Reading and writing of the sensor altitude must be done while the SCD42 is in idle mode. Typically, the sensor altitude is set once after device installation. To save the setting to the EEPROM, the persist setting (see chapter 3.8.1) command must be issued.
- Page 12 [bytes] signal conversion word[0] = ambient P [Pa] / 0xe000 Example: set ambient pressure to 98’700 Pa Write 0xe000 0x03db 0x42 (hexadecimal) Command Ambient P = 98’700 Pa CRC of 0x03db www.sensirion.com Preliminary Version 0.92 – October 2021 12/21...
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Page 13: Field Calibration
Description: To successfully conduct an accurate forced recalibration, the following steps need to be carried out: 1. Operate the SCD42 in the operation mode later used in normal sensor operation for > 3 minutes in an environment with homogenous and constant CO concentration. - Page 14 = 1 → ASC enabled word[0] = 0 → ASC disabled Example: read automatic self-calibration status: disabled Write 0x2313 (hexadecimal) Command Wait 1 ms command execution time Response 0x0000 0x81 (hexadecimal) ASC disabled CRC of 0x0000 www.sensirion.com Preliminary Version 0.92 – October 2021 14/21...
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Page 15: Advanced Features
(RAM) only and will be lost after a power-cycle. The persist_settings command stores the current configuration in the EEPROM of the SCD42, making them persistent across power-cycling. To avoid unnecessary wear of the EEPROM, the persist_settings command should only be sent when persistence is required and if actual changes to the configuration have been made. - Page 16 Description: The reinit command reinitializes the sensor by reloading user settings from EEPROM. Before sending the reinit command, the stop measurement command must be issued. If the reinit command does not trigger the desired re-initialization, a power-cycle should be applied to the SCD42. Table 25: reinit I...
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Page 17: Checksum Calculation
> 0; --crc_bit) { (crc & 0x80) Final XOR 0x00 (crc << 1) ^ CRC8_POLYNOMIAL; Examples CRC (0xBEEF) = 0x92 else (crc << 1); return crc; Table 26 I C CRC properties. www.sensirion.com Preliminary Version 0.92 – October 2021 17/21... -
Page 18: Mechanical Specifications
± 0.3 ± 0.2 Table 27: Nominal dimensions and tolerances SCD42 (all in mm). The weight of the sensor is approx. 0.6 g. Note that the white protection membrane on top of the sensor must not be removed or tampered with to ensure proper sensor operation. -
Page 19: Tape & Reel Package
4.4 Moisture Sensitivity Level Sensirion SCD42 sensors shall be treated according to Moisture Sensitivity Level 1 (MSL1) as described in IPC/JEDEC J-STD- 033B1. Exposure to moisture levels or temperatures before sensor assembly, which exceed the limits as stated in this document, can result in yield loss and sensor performance degradation. -
Page 20: Soldering Instructions
IPC/JEDEC J-STD-020 with a maximum peak temperature of 235°C during up to 30 sec for Pb-free assembly in IR/Convection reflow ovens. Note that due to the comparably large size of the SCD42 sensor significant temperature differences across the sensor element can occur during reflow soldering. Specifically, the temperature within the sensor cap can be higher than the temperature measured at the pad using usual temperature monitoring methods. - Page 21 Warranty SENSIRION warrants solely to the original purchaser of this product for a period of 12 months (one year) from the date of delivery that this product shall be 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 repair and/or replace this product, in SENSIRION’s discretion, free of charge to the Buyer, provided that:...
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