HDC2080 Digital Sensor : Circuit Diagram and Its Specifications

We humans interact with the external environment with the help of senses. A human body has five different types of senses, which help in its proper functioning. In the same way machines and electronics also require some sensing elements to interact with the external environment. Sensors are the devices which machines use as sensing elements. There are different types of sensors for measuring and detecting different physical quantities. Some of the examples of these sensors are the temperature sensor, touch sensor, fire sensor, gas sensor, humidity sensor, light sensor, proximity sensor, etc. Most of these sensors are available as small-sized integrated circuits, which make them easy to interface. One of the examples of such small size, low power consumption humidity sensor is HDC2080 sensor.

What is an HDC2080 Sensor?

HDC2080 is a digital humidity and temperature measuring sensor. It has a humidity sensing element, temperature sensing element, Analog to digital converter, calibrated memory and an I2C interface all embedded on a single 3mm ×3 mm 6-pin IC.

HDC2080
HDC2080

HDC2080 provides programmable resolution for both temperature and humidity measurements. This sensor contains a capacitive sensing element and measures the relative humidity of the environment.

Block Diagram

Block-Diagram-of-HDC2080
Block-Diagram-of-HDC2080

HDC2080 has two types of measurement modes – Auto mode and Trigger on-demand mode. In auto mode, HDC2080 doesn’t require any I2C command to initiate the measurement. While working in this mode, the IC is programmed to perform measurements on a periodic basis.

In trigger on-demand mode, I2C commands are required to initiate the measurements. After completing the conversion, the device goes into sleep mode and waits for another I2C command to start measurement.

HDC2080 has two modes of operation – Sleep mode and measurement mode. The key feature of HDC2080 that makes it suitable for energy harvesting applications is its low power consumption. When applied for these type of applications, HDC2080 spends most of the time in sleep mode. In this mode, the IC’s average power consumption is 50 nA.

When working in a high humidity environment, HDC2080 can face the problem of condensation. To prevent this, the IC is provided with an integrated heating element. This heater, with an operating range of -40°C to 85°C, can be switched on briefly to remove the condensation.

HDC2080 operates as a slave on the I2C bus interface. SDA and SCL open-drain lines are used to make the connection with the I2C interface. HDC2080 also contains an ADC to convert the measurement values from analog to digital.

Circuit Diagram

Proper setup of the sensing element and sensors accuracy, highly affects the accuracy in the measurement of RH and temperature values. Isolating HDC2080 from heat sources such as batteries, display, resistive elements, etc… is recommended to improve the accuracy of the sensor.

Long and prolonged exposure to UV radiation, chemical vapors, visible light can affect the RH% of the sensor.

Pin Configuration of HDC2080

Pin-Diagram-of-HDC2080
Pin-Diagram-of-HDC2080

HDC2080 is available as a 6-pin DMB  3.00mm × 3.0mm sized package.

  • Pin-1 is the serial data line for I2C, SDA pin. A pull-up resistor is connected from this pin to the positive supply voltage.
  • Pin-2, GND, is the ground pin.
  • Pin-3, ADDR, is the address select pin. This pin can be either left unconnected or can be hardwired to ground. When left unconnected or connected to ground the slave address is 1000000. When connected to the positive power supply, the slave address is 1000001.
  • Pin-4, DRDY/INT, is the data ready/interrupt pin.
  • Pin-5, VDD, is the positive supply voltage pin.
  • PIn-6, SCL, is the serial clock line for I2C. A pull-up resistor should be connected from this pin to the positive power supply.

Specifications

Specifications of HDC2080 Digital sensor are as follows-

  • This sensor measures the relative humidity.
  • It contains a capacitive-based sensing element.
  • The relative humidity range of this sensor if from 0 to 100 %.
  • A typical humidity accuracy of HDC2080 is ± 2°C.
  • This sensor has a maximum temperature accuracy of ±0.2°C.
  • Operating temperature range of HDC2080 is from -40°C to 85°C.
  • Functional temperature range of this sensor is from -40°C to 125°C.
  • Average supply current is 300nA for RH% only whereas it is 550nA if both RH% and temperature are calculated.
  • This sensor contains auto-measurement mode.
  • HDC2080 sensor has I2C interface compatibility.
  • Supply voltage range for this IC is from 1.62V to 3.6V.
  • The maximum input voltage required for the proper functioning of this sensor is 3.9V.
  • This IC is available as a small DMB package.
  • To dissipate condensation and moisture a heating element is also embedded on the IC.
  • To provide alerts this IC also contains programmable interrupt thresholds.
  • The sensor can wake-up without the help of any microcontroller.
  • A smaller version of HDC2080, the HDC2010, is also available for applications where the size of PCB is very small.
  • The power consumption requirement of this IC is very low.
  • When used to sense either RH or temperature, HDC2080 has 14-bit resolution.
  • Response time while measuring RH is 8 seconds.

Applications of HDC2080

HDC2080 is an integrated sensor to measure humidity and temperature. This sensor is designed for battery-powered systems. These sensors are used in washers, dryers, home appliances, hospitals, inkjet printers, etc… for measuring humidity. These are digital sensors and can be interfaced with microcontrollers easily.

In HVAC systems the sensor is interfaced with a microcontroller. The microcontroller collects the data from the sensor and based on these data values the heating and cooling systems maintain the environmental temperature at the preferred levels.

Measurement of humidity is also important in medical units, where the change in humidity levels can affect the health of patients severely.

Alternative IC

Some of the IC that can be used as an alternative to HDC2080 sensor are – HDC1010, HDC 1080, HDC2010, etc…

HDC2080 is an ideal choice whee there is a limitation on the physical size of the circuit. Its compact size with low power consumption feature is very useful for battery-powered applications. This IC should not be exposed to chemical fumes and heat for a longer duration. This may lead to a decrease in the accuracy of measurements. Further electrical conditions and storage condition of this IC can be found in the datasheet provided by Texas instrumentations.

Image Credit: Texas Instrumentation

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