SNAS890A February   2025  – June 2025 HDC3120-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Device Power-Up
      2. 7.3.2 Device Disable and Enable
      3. 7.3.3 Conversion of the Signal Output
        1. 7.3.3.1 Relative Humidity (RH%) Measurement
        2. 7.3.3.2 Temperature Measurement
      4. 7.3.4 NIST Traceability and Unique ID
      5. 7.3.5 Output Short Circuit Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 On-Chip Heater
        1. 7.4.1.1 Operating Principle
          1. 7.4.1.1.1 Heater Configuration Example
        2. 7.4.1.2 Heater Electrical Behavior
        3. 7.4.1.3 Heater Temperature Increase
        4. 7.4.1.4 Heater Usage Guidelines
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
    5. 8.5 Storage and PCB Assembly
      1. 8.5.1 Storage and Handling
      2. 8.5.2 Product Storage
      3. 8.5.3 PCB Assembly Flow
      4. 8.5.4 Rework Consideration
      5. 8.5.5 Sensitivity to Chemicals and Vapors
      6. 8.5.6 Exposure to High Temperature and High Humidity Conditions
      7. 8.5.7 Recovering Sensor Performance: Bake and Rehydration Procedure
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

7.3.3.1 Relative Humidity (RH%) Measurement

The RH% can be calculated from the VRH output voltage and the VDD using the equation:

Equation 1. %RH=-12.5+125×VRHVDD=-100.8+1000.8×VRHVDD

Figure 7-8 plots the calculated RH% as a function of normalized VRH/VDD:

HDC3120-Q1 HDC3120-Q1 %RH Output ProfileFigure 7-8 HDC3120-Q1 %RH Output Profile

Alternatively, to examine the voltage gain of the sensor for humidity measurements, the VRH voltage can also be expressed as a function of VDD and %RH in the following voltage sensitivity equation:

Equation 2. VRH=VDD×%RH×8mV%RH+0.1
  • 8mV/%RH represents the gain of the sensor which scales with VDD, showing voltage change per %RH.
  • The voltage spans from 0.1 × VDD, the sensor offset at 0% RH, to 0.9 × VDD, representing 100% RH

Figure 7-9 illustrates the RH output voltage as a function of RH% at different VDD levels. Figure 7-10 presents the same data, but with the RH output voltage normalized to VDD.

HDC3120-Q1 RH% Sensor Output (VRH) vs RH%Figure 7-9 RH% Sensor Output (VRH) vs RH%
HDC3120-Q1 Normalized RH% Sensor Output (VRH) vs RH%Figure 7-10 Normalized RH% Sensor Output (VRH) vs RH%

Table 7-1 provides some examples of the VRH voltage reading at various %RH and VDD levels. Note even though the VRH voltage vary with VDD at the same RH% level, VRH/VDD ratio remains constant, providing accurate measurements. This ratiometric design makes the HDC3120-Q1 sensor reading stable across supply variations.

Table 7-1 VRH Voltage at Various %RH and VDD Levels
VDD = 1.8VVDD = 2.5VVDD = 3.3VVDD = 5.0VVRH/VDD Ratio
%RH= 0%0.180.250.330.500.10
%RH= 25%0.540.750.991.500.30
%RH= 50%0.901.251.652.500.50
%RH= 85%1.401.952.573.900.78
%RH= 100%1.622.252.974.500.90
Sensor Gain14.4mV/%RH20mV/%RH26.4mV/%RH40.0mV/%RH
Sensor Offset180mV250mV330mV500mV