This version is outdated by a newer approved version.
This version (07 Jul 2017 17:15) is a draft.
Approvals: 0/1
This version (07 Jul 2017 17:15) is a draft.Approvals: 0/1
This is an old revision of the document!
Table of Contents
EVAL-CN0395-ARDZ Shield
The circuit below is an arduino compatible, single supply 16-bit volatile organic compound detector using a metal oxide sensor. It uses ADN8810 to precisely control the current running through the sensor to get to within the 1% voltage accuracy needed for the heating element of the sensor.
CN0395 measures indoor air quality by utilizing a Metal Oxide Sensor to detect gases composed of volatile organic compounds. The sensor is composed of a heating resistor and a sensing resistor. When the sense resistor is heated its value changes as a function of the concentrations of different gasses.
Connectors and Jumper Configurations
Headers
P2 header selects the current path from the current output DAC, ADN8810. It is populated across RH+ by default.
| Silkscreen | Current Path | Pins |
| RCAL1 | 71.5Ω | 1 & 2 |
| RCAL1 | 10.0Ω | 3 & 4 |
| RH+ | Heating Resistor | 5 & 6 |
A jumper is placed across pins 2 & 3 or GND, as default to maintain the performance specifications of ADN8810.
Sensor
CN0395 has the TGS8100 on board as default. Using a different set of sensors require a recalculation and replacement of the sense resistors that sets the full scale current for the device. Provision for alphasense sensors or with similar footprint is available and a screw terminal is also in place for any other types of sensors.
The calculation for the sense resistor and placement of the correct sense resistors are crucial to proper operation of the board to not violate absolute maximum ratings of the sensors
Recommended Sensors
Spacers
Spacers that could cater various surface mount and through hole packages are available on the board to make some modifications on the board easier.
Resistor spacers, R17_SPACER and R19_SPACER, are used to hold the sense resistors to select the maximum output current of the ADN8810. Changing these maximum output current of the ADN8810 allows the board to cater multiple types of sensor that use up to 300mA of current for measurements.
Sense resistors (RSN) can be calculated by using the formula below:
RSN= 4.096/(10* Full Scale Current)
Button
Pressing push button S2 resets the temperature and humidity sensor SHT30 from Sensirion.
Schematic, PCB Layout, Bill of Materials
EVAL-CN0395-ARDZ Design & Integration Files
- Schematics
- PCB Layout
- Bill of Materials
- Allegro Project
Software
resources/eval/user-guides/eval-adicup360/hardware/cn0395.1499440534.txt.gz · Last modified: 07 Jul 2017 17:15 by Ramon Glenn Amparo