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

8.2.1 Design Requirements

The TMP464 device is designed to be used with either discrete transistors or substrate transistors built into processor chips, field programmable gate arrays (FPGAs), and application-specific integrated circuits (ASICs) ; see Figure 21. Either NPN or PNP transistors can be used, as long as the base-emitter junction is used as the remote temperature sensor. 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 (η-factor) and current excitation used by the TMP464 device 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 TMP464 uses 7.5 μA (typical) for ILOW and 120 μA (typical) for IHIGH.

The ideality factor (η-factor) is a measured characteristic of a remote temperature sensor diode as compared to an ideal diode. The TMP464 allows for different η-factor values; see the η-Factor Correction Register section.

The η-factor for the TMP464 device is trimmed to 1.008. For transistors that have an ideality factor that does not match the TMP464 device, Equation 4 can be used to calculate the temperature error.

NOTE

For Equation 4 to be used correctly, the actual temperature (°C) must be converted to Kelvin (K).
Equation 4. TMP464 q_terr1_bos792.gif

where

  • TERR = error in the TMP464 device because η ≠ 1.008
  • η = ideality factor of the remote temperature sensor
  • T(°C) = actual temperature, and

In Equation 4, the degree of delta is the same for °C and K.

For η = 1.004 and T(°C) = 100°C:

Equation 5. TMP464 q_terr2_sbos722.gif

If a discrete transistor is used as the remote temperature sensor with the TMP464 device, then select the transistor according to the following criteria for best accuracy:

  • Base-emitter voltage is > 0.25 V at 7.5 μA, at the highest-sensed temperature.
  • Base-emitter voltage is < 0.95 V at 120 μA, at the lowest-sensed temperature.
  • Base resistance is < 100 Ω.
  • Tight control of VBE characteristics indicated by small variations in hFE (50 to 150).

Based on these criteria, TI recommends using a MMBT3904 (NPN) or a MMBT3906 (PNP) transistor.