The SVM30 measures concentration of VOC, relative humidity and temperature and calculates CO2eq from measured concentration of H2. It uses SGP30 and SHTC1 sensors. At first glance, however, it seems to be quite big, check it out with us.
On the first sight, the PCB looks really huge with the big connector. Any average PCB designer can do the same on a third-sized PCB. Let's take a closer look at it.
SGP30 current consumption is approx. 50mA from 1.8V, so power dissipation is 90mW. Voltage regulator from 5V to 1,8V adds another 160mW. SHTC1 average current consumption is 8.6uA only, which is insignificant. Generated heat spreads by conduction through the PCB and convection of heated air. Good PCB design has to minimize both thermal transfers.
Sensirions’ extensive experiments allowed them to formulate a rule that a distance of around 5cm (~ 2 in.) between SGP30 and SHTx sensors and milling slits in the PCB around the SHTx is sufficient. When you look at the PCB you will see slit around SHTC1 and even two more slits because we have additional source of heat on the PCB– voltage regulator. There are only necessary tracks on the PCB side where SHTC1 is assembled and no GND ground plane to minimise transfer through copper. These measures minimise heat transfer by conduction.
The SVM30 module must be placed in the housing so that the air flows from the SHTC1 towards the SGP30, which is also the optimum airflow marked on the PCB.
PCB size is 39x15mm, do you still think that it is too big?
What is Onboard
The SGP30 gas sensor that combines multiple metal-oxide sensing elements – the pixels – on one chip, thereby allows measuring concentration of VOC (volatile organic compounds) and H2 and calculating CO2 equivalent signal (CO2eq) from measured H2 concentration. The sensing element features unmatched robustness against contamination by siloxanes often present in indoor environment, enabling unique long-term stability and low drift.
SHTC1 humidity and temperature sensor that covers a relative humidity (RH) measurement range of 0 to 100% and a temperature measurement range of -20 to 85°C with a typical accuracy of ±5% RH and ±1°C.
It is well known that all MOX sensors are sensitive to water vapour. SGP30 supports humidity compensation. Just read the actual relative humidity and temperature from SHTC1, calculate absolute humidity, convert result to format required by SGP30 and write it to SGP30 by using the “Set humidity” command.
Module uses Scondar SCT2001WR-S-4P connector (compatible to JST part no. S4B-PH-SM4-TB). To support development, we offer mating connector, JST PHR-4 housing and pre-crimped wires.
Both SGP30 and SHTC1 support I2C fast (400 kHz) mode but because of capacitive coupling between wires in cable, max. 100 kHz SCL frequency is recommended for communication.
The SVM30 is especially suitable for those who prefer the use of ready-made modules to their own development. SVM30 is perfect for air purifiers, but also for applications in heating, ventilation and air conditioning (HVAC).
The most convenient way how to evaluate SVM30 performance is using the Sensirion SEK Sensor Bridge from evaluation kit SEK-SHTxx/SGP30, SEK-SVM30-J, (SVM30-J with cable) and Sensirion Control Center software. Software is available for Windows, Linux and macOS.
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Date of publishing 06.06.2019 When you issue article on your website, please give its source: http://www.soselectronic.com/articles/sensirion/svm30-module-a-complete-solution-for-hvac-applications-2322