SBOS876B September   2017  – February 2020 TMP461-SP

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     Simplified Block Diagram
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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 Two-Wire Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Temperature Measurement Data
        1. 7.3.1.1 Standard Binary to Decimal Temperature Data Calculation Example
        2. 7.3.1.2 Standard Decimal to Binary Temperature Data Calculation Example
      2. 7.3.2 Series Resistance Cancellation
      3. 7.3.3 Differential Input Capacitance
      4. 7.3.4 Filtering
      5. 7.3.5 Sensor Fault
      6. 7.3.6 ALERT and THERM Functions
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode (SD)
    5. 7.5 Programming
      1. 7.5.1 Serial Interface
        1. 7.5.1.1 Bus Overview
        2. 7.5.1.2 Bus Definitions
        3. 7.5.1.3 Serial Bus Address
        4. 7.5.1.4 Read and Write Operations
        5. 7.5.1.5 Timeout Function
        6. 7.5.1.6 High-Speed Mode
      2. 7.5.2 General-Call Reset
    6. 7.6 Register Map
      1. 7.6.1 Register Information
        1. 7.6.1.1  Pointer Register
        2. 7.6.1.2  Local and Remote Temperature Registers
        3. 7.6.1.3  Status Register
        4. 7.6.1.4  Configuration Register
        5. 7.6.1.5  Conversion Rate Register
        6. 7.6.1.6  One-Shot Start Register
        7. 7.6.1.7  Channel Enable Register
        8. 7.6.1.8  Consecutive ALERT Register
        9. 7.6.1.9  η-Factor Correction Register
        10. 7.6.1.10 Remote Temperature Offset Register
        11. 7.6.1.11 Manufacturer Identification Register
  8. 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. 8.2.3 Application Curve
    3. 8.3 Radiation Environments
      1. 8.3.1 Single Event Latch-Up
      2. 8.3.2 Single Event Functional Interrupt
      3. 8.3.3 Single Event Upset
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.2.2 Detailed Design Procedure

The local temperature sensor inside the TMP461-SP device monitors the ambient air around the device. The thermal time constant for the TMP461-SP device is approximately two seconds. This constant implies that if the ambient air changes quickly by 100°C, then the TMP461-SP device takes approximately 10 seconds (that is, five thermal time constants) to settle to within 1°C of the final value. In most applications, the TMP461-SP package is in electrical, and therefore thermal, contact with the printed circuit board (PCB), as well as subjected to forced airflow. The accuracy of the measured temperature directly depends on how accurately the PCB and forced airflow temperatures represent the temperature that the TMP461-SP is measuring. Additionally, the internal power dissipation of the TMP461-SP can cause the temperature to rise above the ambient or PCB temperature. The internal power dissipated as a result of exciting the remote temperature sensor is negligible because of the small currents used. Equation 6 can be used to calculate the average conversion current for power dissipation and self-heating based on the number of conversions per second and temperature sensor channel enabled. Equation 7 shows an example with local and remote sensor channels enabled and 16 conversions per second; see the Electrical Characteristics table for typical values required for these calculations. For a 3.3-V supply and a conversion rate of 16 conversions per second, the TMP461-SP device dissipates 0.531 mW (PDIQ = 3.3 V × 161 μA) when both the remote and local channels are enabled.

Equation 6. TMP461-SP q_avg_conv_sbos722.gif
Equation 7. TMP461-SP q_avg_conv_2_sbos722.gif

The temperature measurement accuracy of the TMP461-SP device depends on the remote and local temperature sensor being at the same temperature as the system point being monitored. If the temperature sensor is not in good thermal contact with the part of the system being monitored, then there is a delay between the sensor response and the system changing temperature. This delay is usually not a concern for remote temperature-sensing applications that use a substrate transistor (or a small, SOT23 transistor) placed close to the device being monitored.