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

7.4.1.1 Operating Principle

The on-chip heater in the HDC3120-Q1 is implemented as a resistive heating element integrated into the sensor die. The heater is controlled using the dedicated HEAT_EN pin. Driving HEAT_EN high enables the heater; driving the heater low disables the heater. To prevent accidental activation, HEAT_EN must not be left floating—tie this pin to ground if the heater function is unused.

When HEAT_EN is asserted (set high), a built-in startup delay of approximately 130ms occurs before the heater current is applied. This delay verifies stable activation and prevents unintended heater operation due to spurious pulses or brief transients. When HEAT_EN is deasserted (set low), the heater turns off within 0.45ms, quickly halting heat generation.

Note:

While the heater is active, the sensor does not measure true ambient temperature or humidity. Instead, the temperature sensor reports the elevated junction temperature, and the relative humidity reading appears artificially lower due to the increased local temperature. After a heating cycle, the sensor requires time to cool and equilibrate with the environment before accurate RH/T measurements can resume.

For reliable humidity measurements following a heating cycle, allow a minimum of 30 seconds recovery time in still air conditions. Actual recovery time depends on final heater temperature, airflow, and ambient thermal characteristics.