SBOS891B October   2018  – April 2021 TMP144

PRODUCTION DATA  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and Functions
  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 UART Interface Timing
    7. 6.7 Timing Diagrams
    8. 6.8 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Power Up
      2. 7.3.2 Digital Temperature Output
      3. 7.3.3 Timeout Function
    4. 7.4 Device Functional Modes
      1. 7.4.1 Continuous Conversion Mode
      2. 7.4.2 Shutdown Mode
      3. 7.4.3 One-Shot Mode
      4. 7.4.4 Extended Temperature Mode
      5. 7.4.5 Temperature Alert Function
      6. 7.4.6 Interrupt Functionality
    5. 7.5 SMAART Wire / UART Interface
      1. 7.5.1 Communication Protocol
      2. 7.5.2 Global Software Reset
      3. 7.5.3 Global Initialization and Address Assignment Sequence
      4. 7.5.4 Global Clear Interrupt
      5. 7.5.5 Global Read and Write
      6. 7.5.6 Individual Read and Write
    6. 7.6 Register Maps
      1. 7.6.1 Temperature Result Register (P[1:0] = 00) [reset = 0000h]
      2. 7.6.2 Configuration Register (P[1:0] = 01) [reset = 0200h]
      3. 7.6.3 Temperature Low Limit Register (P[1:0] = 10) [reset = F600h]
      4. 7.6.4 Temperature High Limit Register (P[1:0] = 11) [reset = 3C00h]
  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
        1. 8.2.2.1 Trace Length
        2. 8.2.2.2 Voltage Drop Effect
        3. 8.2.2.3 Power Supply Noise Filtering
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Nomenclature
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

Global Initialization and Address Assignment Sequence

At device power-up, every TMP144 in the daisy-chain is connected in transparent mode, as shown in Figure 7-7.

GUID-20200819-CA0I-CD0L-NHF2-QR3SXVJR16K3-low.gifFigure 7-7 TMP144 Daisy-Chain: Bus Status at Start of Global Initialization

As shown in Figure 7-8, the host must send the initialization command (C[7:0] = 10001100) for the bus to program its internal address, depending on the number of devices on the bus.

GUID-20200826-CA0I-VFBQ-PJZL-TDFV5TH8ZXZ1-low.gif Figure 7-8 Global Initialization and Address Assignment Command Flow.
Each TMP144 in the chain interprets the initialization command byte and disconnects the chain, as shown in Figure 7-9.

GUID-18DB8720-7372-4DC7-8E43-BE04CD3C033F-low.gif Figure 7-9 TMP144 Daisy-Chain: Bus Status at Start of Address Assignment

The host must then send the address assignment command, consisting of C[7:4] = 1001 and C[3:0] = 0000, where C[3:0] represents the address of the first device in the chain. This word is stored internally as its device ID. The first device increments the unit in the device address and then reconnects the bus, as shown in Figure 7-10. This address is then sent to the next device in the chain.

GUID-20200819-CA0I-1BGB-3RWH-CRGHMGHHPH7T-low.gif Figure 7-10 TMP144 Daisy-Chain: Bus Status After First Device Address Assignment

After all devices on the chain have received the respective addresses, the host receives the last programmed address on the chain + 1. The host can use this information to determine the total number of devices in the chain and the respective address of each device.

After the initialization sequence, every device can be addressed individually or through global commands. This global initialization sequence is a requirement and must be performed before any other communication.