SBOS441I September   2009  – October 2019 TMP431 , TMP432

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application Schematics
  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 Timing Requirements
    7. 6.7 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Temperature Measurement Data
      2. 8.3.2 Beta Compensation
      3. 8.3.3 Series Resistance Cancellation
      4. 8.3.4 Differential Input Capacitance
      5. 8.3.5 Filtering
      6. 8.3.6 Sensor Fault
      7. 8.3.7 THERM and ALERT/THERM2
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode (SD)
      2. 8.4.2 One-Shot Mode
    5. 8.5 Programming
      1. 8.5.1  Serial Interface
      2. 8.5.2  Bus Overview
      3. 8.5.3  Timing Diagrams
      4. 8.5.4  Serial Bus Address
      5. 8.5.5  Read and Write Operations
      6. 8.5.6  Undervoltage Lockout
      7. 8.5.7  Timeout Function
      8. 8.5.8  High-Speed Mode
      9. 8.5.9  General Call Reset
      10. 8.5.10 SMBus Alert Function
    6. 8.6 Register Maps
      1. 8.6.1  Pointer Register
      2. 8.6.2  Temperature Registers
      3. 8.6.3  Limit Registers
      4. 8.6.4  Status Registers
        1. 8.6.4.1 TMP431 Status Register
        2. 8.6.4.2 TMP432 Status Register
      5. 8.6.5  Configuration Register 1
      6. 8.6.6  Configuration Register 2
      7. 8.6.7  Conversion Rate Register
      8. 8.6.8  Beta Compensation Configuration Register
      9. 8.6.9  η-Factor Correction Register
      10. 8.6.10 Software Reset
      11. 8.6.11 Consecutive Alert Register
      12. 8.6.12 Therm Hysteresis Register
      13. 8.6.13 Identification Registers
      14. 8.6.14 Open Status Register
      15. 8.6.15 Channel Mask Register
      16. 8.6.16 High Limit Status Register
      17. 8.6.17 Low Limit Status Register
      18. 8.6.18 THERM Limit Status Register
  9. 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 Examples
  12. 12Device and Documentation Support
    1. 12.1 Related Links
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

9.2.1 Design Requirements

The TMP43x are designed to be used with either discrete transistors or substrate transistors built into processor chips and ASICs. Either NPN- or PNP-type transistors can be used, as long as the base-emitter junction is used as the remote temperature sense. NPN transistors must be diode-connected. PNP transistors can either be transistor- or diode- connected (see Figure 21).

Errors in remote temperature sensor readings are typically the consequence of the ideality factor and current excitation used by the TMP43x versus the manufacturer-specified operating current for a given transistor. Some manufacturers specify a high-level and low-level current for the temperature-sensing substrate transistors. The TMP43x use 6 μA for ILOW and 120 μA for IHIGH. The TMP43x allow for different η-factor values; see η-Factor Correction Register.

The ideality factor (η) is a measured characteristic of a remote temperature sensor diode as compared to an ideal diode. The ideality factor for the TMP43x is trimmed to be 1.008. For transistors whose ideality factor does not match the TMP43x, Equation 6 can be used to calculate the temperature error. Note that for the equation to be used correctly, actual temperature (°C) must be converted to Kelvin (K).

Equation 6. TMP431 TMP432 q_terr_bos441.gif

where

  • η = Ideality factor of remote temperature sensor
  • T(°C) = actual temperature
  • TERR = Error in TMP43x reading due to η ≠ 1.008
  • Degree delta is the same for °C and K

For n = 1.004 and T(°C) = 100°C:

Equation 7. TMP431 TMP432 q_terr_02_bos441.gif

If a discrete transistor is used as the remote temperature sensor with the TMP43x, the best accuracy can be achieved by selecting the transistor according to the following criteria:

  1. Base-emitter voltage > 0.25 V at 6 μA, at the highest sensed temperature
  2. Base-emitter voltage < 0.95 V at 120 μA, at the lowest sensed temperature
  3. Base resistance < 100 Ω
  4. Tight control of VBE characteristics indicated by small variations in hFE (that is, 50 to 150)

Based on these criteria, two recommended small-signal transistors are the 2N3904 (NPN) or 2N3906 (PNP).