SBOSA45D February   2022  – January 2025 TMP1826

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Description (cont.)
  6. 5 Device Comparison
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 1-Wire® Interface Timing
    7. 7.7 EEPROM Characteristics
    8. 7.8 Timing Diagrams
    9. 7.9 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Power Up
      2. 8.3.2  Power Mode Switch
      3. 8.3.3  Bus Pullup Resistor
      4. 8.3.4  Temperature Results
      5. 8.3.5  Temperature Offset
      6. 8.3.6  Temperature Alert
      7. 8.3.7  Standard Device Address
        1. 8.3.7.1 Unique 64-Bit Device Address and ID
      8. 8.3.8  Flexible Device Address
        1. 8.3.8.1 Non-Volatile Short Address
        2. 8.3.8.2 IO Hardware Address
        3. 8.3.8.3 Resistor Address
        4. 8.3.8.4 Combined IO and Resistor Address
      9. 8.3.9  CRC Generation
      10. 8.3.10 Functional Register Map
      11. 8.3.11 User Memory Map
      12. 8.3.12 Bit Communication
        1. 8.3.12.1 Host Write, Device Read
        2. 8.3.12.2 Host Read, Device Write
      13. 8.3.13 Bus Speed
      14. 8.3.14 NIST Traceability
    4. 8.4 Device Functional Modes
      1. 8.4.1 Conversion Modes
        1. 8.4.1.1 Basic One-Shot Conversion Mode
        2. 8.4.1.2 Auto Conversion Mode
        3. 8.4.1.3 Stacked Conversion Mode
        4. 8.4.1.4 Continuous Conversion Mode
      2. 8.4.2 Alert Function
        1. 8.4.2.1 Alert Mode
        2. 8.4.2.2 Comparator Mode
      3. 8.4.3 1-Wire® Interface Communication
        1. 8.4.3.1 Bus Reset Phase
        2. 8.4.3.2 Address Phase
          1. 8.4.3.2.1 READADDR (33h)
          2. 8.4.3.2.2 MATCHADDR (55h)
          3. 8.4.3.2.3 SEARCHADDR (F0h)
          4. 8.4.3.2.4 ALERTSEARCH (ECh)
          5. 8.4.3.2.5 SKIPADDR (CCh)
          6. 8.4.3.2.6 OVD SKIPADDR (3Ch)
          7. 8.4.3.2.7 OVD MATCHADDR (69h)
          8. 8.4.3.2.8 FLEXADDR (0Fh)
        3. 8.4.3.3 Function Phase
          1. 8.4.3.3.1  CONVERTTEMP (44h)
          2. 8.4.3.3.2  WRITE SCRATCHPAD-1 (4Eh)
          3. 8.4.3.3.3  READ SCRATCHPAD-1 (BEh)
          4. 8.4.3.3.4  COPY SCRATCHPAD-1 (48h)
          5. 8.4.3.3.5  WRITE SCRATCHPAD-2 (0Fh)
          6. 8.4.3.3.6  READ SCRATCHPAD-2 (AAh)
          7. 8.4.3.3.7  COPY SCRATCHPAD-2 (55h)
          8. 8.4.3.3.8  READ EEPROM (F0h)
          9. 8.4.3.3.9  GPIO WRITE (A5h)
          10. 8.4.3.3.10 GPIO READ (F5h)
      4. 8.4.4 NVM Operations
        1. 8.4.4.1 Programming User Data
        2. 8.4.4.2 Register and Memory Protection
          1. 8.4.4.2.1 Scratchpad-1 Register Protection
          2. 8.4.4.2.2 User Memory Protection
    5. 8.5 Programming
      1. 8.5.1 Single Device Temperature Conversion and Read
      2. 8.5.2 Multiple Device Temperature Conversion and Read
      3. 8.5.3 Register Scratchpad-1 Update and Commit
      4. 8.5.4 Single Device EEPROM Programming and Verify
      5. 8.5.5 Single Device EEPROM Page Lock Operation
      6. 8.5.6 Multiple Device IO Read
      7. 8.5.7 Multiple Device IO Write
    6. 8.6 Register Map
      1. 8.6.1  Temperature Result LSB Register (Scratchpad-1 offset = 00h) [reset = 00h]
      2. 8.6.2  Temperature Result MSB Register (Scratchpad-1 offset = 01h) [reset = 00h]
      3. 8.6.3  Status Register (Scratchpad-1 offset = 02h) [reset = 3Ch]
      4. 8.6.4  Device Configuration-1 Register (Scratchpad-1 offset = 04h) [reset = 70h]
      5. 8.6.5  Device Configuration-2 Register (Scratchpad-1 offset = 05h) [reset = 80h]
      6. 8.6.6  Short Address Register (Scratchpad-1 offset = 06h) [reset = 00h]
      7. 8.6.7  Temperature Alert Low LSB Register (Scratchpad-1 offset = 08h) [reset = 00h]
      8. 8.6.8  Temperature Alert Low MSB Register (Scratchpad-1 offset = 09h) [reset = 00h]
      9. 8.6.9  Temperature Alert High LSB Register (Scratchpad-1 offset = 0Ah) [reset = F0h]
      10. 8.6.10 Temperature Alert High MSB Register (Scratchpad-1 offset = 0Bh) [reset = 07h]
      11. 8.6.11 Temperature Offset LSB Register (Scratchpad-1 offset = 0Ch) [reset = 00h]
      12. 8.6.12 Temperature Offset MSB Register (Scratchpad-1 offset = 0Dh) [reset = 00h]
      13. 8.6.13 IO Read Register [reset = F0h]
      14. 8.6.14 IO Configuration Register [reset = 00h]
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Bus Powered Application
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
      2. 9.2.2 Supply Powered Application
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
      3. 9.2.3 UART Interface for Communication
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.3 Bus Pullup Resistor

The bus pullup resistance value selected is important for communication as per the speed mode and verifying that the minimal possible energy is consumed in the application. If the resistor value is too small, the design can violate the VOL limits on the SDQ pin.

Consider the total SDQ pins and bus capacitance along with the bus leakage current when selecting the pullup resistor. The pullup resistance value selected must also verify that the signal level reaches VIH as per the timing requirements for standard and overdrive mode.

In bus powered mode of operation, the device charges the internal capacitor through the SDQ pin and the pullup resistor. This charge on the capacitor is used during bus communication, when the SDQ pin low. For other high current functions like thermal conversion and EEPROM access, the bus is held idle to verify that the device can draw current through the pullup resistor. The SDQ pin voltage during the high current operation must be maintained to provide sufficient operating margins. For VPUR ≤ 2.0 V, use Equation 1. For VPUR > 2.0 V, use Equation 2 to calculate the pullup resistor value.

Equation 1. V P U R   –   V O L M A X 4   ×   10 – 3   < R P U R < V P U R   –   1.6 I P U ( M I N )
Equation 2. V P U R   –     V O L ( M A X ) 4   ×   10 – 3   <   R P U R   <   V P U R   –     V I H ( M I N )   I P U ( M I N )

When the device is used in VDD or supply powered mode, a larger pullup resistor value can be used, as the SDQ pin is used only for communication. The user must verify that the pullup resistor value selected must be able to support the timing for the required bus speed of operation.

For low current consumption devices like the TMP1826, selecting the correct pullup resistor value allows the application to avoid low impedance current path components for bus powered mode of operation while maintaining communication speeds and device parameters as per the electrical specification. For multiple devices on the bus, a low impedance current path is recommended.