SBOS835C May   2017  – October 2019 TMP464

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Schematic
  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
      2. 7.3.2 Series Resistance Cancellation
      3. 7.3.3 Differential Input Capacitance
      4. 7.3.4 Sensor Fault
      5. 7.3.5 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
          1. 7.5.1.4.1 Single Register Reads
          2. 7.5.1.4.2 Block Register Reads
        5. 7.5.1.5 Timeout Function
        6. 7.5.1.6 High-Speed Mode
      2. 7.5.2 TMP464 Register Reset
      3. 7.5.3 Lock Register
    6. 7.6 Register Maps
      1. 7.6.1 Register Information
        1. 7.6.1.1  Pointer Register
        2. 7.6.1.2  Local and Remote Temperature Value Registers
        3. 7.6.1.3  Software Reset Register
        4. 7.6.1.4  THERM Status Register
        5. 7.6.1.5  THERM2 Status Register
        6. 7.6.1.6  Remote Channel Open Status Register
        7. 7.6.1.7  Configuration Register
        8. 7.6.1.8  η-Factor Correction Register
        9. 7.6.1.9  Remote Temperature Offset Register
        10. 7.6.1.10 THERM Hysteresis Register
        11. 7.6.1.11 Local and Remote THERM and THERM2 Limit Registers
        12. 7.6.1.12 Block Read - Auto Increment Pointer
        13. 7.6.1.13 Lock Register
        14. 7.6.1.14 Manufacturer and Device Identification Plus Revision Registers
  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
  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 TMP464 is influenced by the ambient air around the device but mainly monitors the PCB temperature that it is mounted to. The thermal time constant for the TMP464 device is approximately two seconds. This constant implies that if the ambient air changes quickly by 100°C, then the TMP464 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 TMP464 package is in electrical (and therefore thermal) contact with the printed-circuit board (PCB), and 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 TMP464 device is measuring. Additionally, the internal power dissipation of the TMP464 device can cause the temperature to rise above the ambient or PCB temperature. The internal power is negligible because of the small current drawn by the TMP464 device.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 all remote sensor channels enabled and conversion rate of 1 conversion 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 1 conversion per second, the TMP464 device dissipates 0.143 mW (PDIQ = 3.3 V × 43 μA) when both the remote and local channels are enabled.

Equation 6. TMP464 q_average_conv_TMP468.gif
Equation 7.
Equation 8. TMP464 q_avg_conv_2_sbos835.gif

The temperature measurement accuracy of the TMP464 device depends on the remote and local temperature sensor being at the same temperature as the monitored system point. If the temperature sensor is not in good thermal contact with the part of the monitored system, 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, SOT-23 transistor) placed close to the monitored device.