SNAS778A June   2021  – September 2021 HDC3020 , HDC3021 , HDC3022

ADVANCE INFORMATION  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Switching Characteristics
    7. 7.7 Timing Diagram
    8. 7.8 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Factory Installed Polyimide Tape
      2. 8.3.2  Factory Installed IP67 Protection Cover
      3. 8.3.3  Measurement of Relative Humidity and Temperature
      4. 8.3.4  Drift Correction: Accuracy Restoration
      5. 8.3.5  NIST Traceability of Relative Humidity and Temperature Sensor
      6. 8.3.6  Measurement Modes: Trigger-On Demand vs. Auto Measurement
      7. 8.3.7  Heater
      8. 8.3.8  ALERT Output With Programmable Interrupts
      9. 8.3.9  Checksum Calculation
      10. 8.3.10 Programmable Offset of Relative Humidity and Temperature Results
    4. 8.4 Device Functional Modes
      1. 8.4.1 Sleep Mode vs. Measurement Mode
    5. 8.5 Programming
      1. 8.5.1 I2C Interface
      2. 8.5.2 I2C Serial Bus Address Configuration
      3. 8.5.3 I2C Write - Send Device Command
      4. 8.5.4 I2C Read - Retrieve Single Data Result
      5. 8.5.5 I2C Read - Retrieve Multi Data Result
      6. 8.5.6 I2C Repeated START - Send Command and Retrieve Data Results
      7. 8.5.7 Command Table and Detailed Description
        1. 8.5.7.1 Reset
          1. 8.5.7.1.1 Soft Reset
          2. 8.5.7.1.2 I2C General Call Reset
        2. 8.5.7.2 Trigger-On Demand
        3. 8.5.7.3 Auto Measurement Mode
          1. 8.5.7.3.1 Auto Measurement Mode: Enable and Configure Measurement Interval
          2. 8.5.7.3.2 Auto Measurement Mode: Measurement Readout
          3. 8.5.7.3.3 Auto Measurement Mode: Exit
          4. 8.5.7.3.4 Auto Measurement Mode: Measurement History Readout
          5. 8.5.7.3.5 Override Default Device Power-On and Device-Reset State
        4. 8.5.7.4 ALERT Output Configuration
          1. 8.5.7.4.1 ALERT Output: Environmental Tracking of Temperature and Relative Humidity
          2. 8.5.7.4.2 ALERT Output: Representation of Environmental Thresholds and Default Threshold Values
          3. 8.5.7.4.3 ALERT Output: Steps to Calculate and Program Environmental Thresholds
          4. 8.5.7.4.4 ALERT Output: Deactivation of Environmental Tracking
          5. 8.5.7.4.5 ALERT Output: Transfer Thresholds into Non-Volatile Memory
        5. 8.5.7.5 Programmable Measurement Offset
          1. 8.5.7.5.1 Representation of Offset Value and Factory Shipped Default Value
          2. 8.5.7.5.2 Factory Shipped Default Offset Values
          3. 8.5.7.5.3 Calculate Relative Humidity Offset Value
          4. 8.5.7.5.4 Calculate Temperature Offset Value
          5. 8.5.7.5.5 Write an Offset Value
          6. 8.5.7.5.6 Verify a Programmed Offset Value
        6. 8.5.7.6 Status Register
        7. 8.5.7.7 Heater: Enable and Disable
        8. 8.5.7.8 Read NIST ID/Serial Number
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
    3. 11.3 Storage and PCB Assembly
      1. 11.3.1 Storage and Handling
      2. 11.3.2 Soldering Reflow
      3. 11.3.3 Rework
      4. 11.3.4 Exposure to High Temperature and High Humidity Conditions
      5. 11.3.5 Bake/Rehydration Procedure
  12. 12Device and Documentation Support
    1. 12.1 Documentation Support
      1. 12.1.1 Related Documentation
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information
    1. 13.1 Package Option Addendum
    2. 13.2 Tape and Reel Information

Package Options

Mechanical Data (Package|Pins)
  • DEF|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

Checksum Calculation

Error checking of data is supported with a Checksum Calculation. The 8-bit CRC checksum transmitted after each data word is generated by a CRC algorithm. Table 8-1 shows the CRC properties. The CRC covers the contents of the two previously transmitted data bytes. To calculate the checksum, only these two previously transmitted data bytes are used.

A CRC byte is sent by the HDC302x to the I2C controller in the following cases:

  1. Following the transmission of a relative humidity measurement
  2. Following the transmission of a temperature measurement
  3. Following the transmission of the contents of the Table 8-12
  4. Following the transmission of any of the programmed ALERT limit values (High Alert, Set; High Alert, Clear; Low Alert, Set; Low Alert, Clear)

A CRC byte must be sent by the I2C controller to the HDC302x in the following cases:

  1. Following the configuration of any of the ALERT limit values (High Alert, Set; High Alert, Clear; Low Alert, Set; Low Alert, Clear).

Table 8-1 HDC302x CRC Properties
PROPERTYVALUE
NameCRC-8
Width8 bit
Protected DataRead and/or Write Data
Polynomial0x31 (x8 + x5 + x4 + 1)
Initialization0xFF
Reflect InputFalse
Reflect OutputFalse
Final XOR0x00
ExamplesCRC of 0xABCD = 0x6F

Retrieving the CRC byte from the HDC302x is optional. A NACK can be issued by the I2C controller prior to reception of the CRC byte to cancel, as shown in Figure 8-1 and Figure 8-2.

GUID-F983C560-428D-4D4D-90F6-DB6C7CF6D369-low.gifFigure 8-1 Example I2C NACK to Discard CRC Byte Corresponding to Humidity Measurement Readout
GUID-F7F5A595-BA37-48AD-ABB1-D270A04C2204-low.gifFigure 8-2 Example I2C NACK to Discard CRC Byte Corresponding to Temperature Measurement Readout