SNIS189D June   2015  – June 2018 LMT01

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
    1.     LMT01 Accuracy
  3. 3 Description
    1.     2-Pin IC Temperature Sensor
  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  Electrical Characteristics - TO-92/LPG Pulse Count to Temperature LUT
    7. 6.7  Electrical Characteristics - WSON/DQX Pulse Count to Temperature LUT
    8. 6.8  Switching Characteristics
    9. 6.9  Timing Diagram
    10. 6.10 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 Output Interface
      2. 7.3.2 Output Transfer Function
      3. 7.3.3 Current Output Conversion to Voltage
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Mounting, Temperature Conductivity, and Self-Heating
    2. 8.2 Typical Application
      1. 8.2.1 3.3-V System VDD MSP430 Interface - Using Comparator Input
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Setting the MSP430 Threshold and Hysteresis
        3. 8.2.1.3 Application Curves
    3. 8.3 System Examples
  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

9 Power Supply Recommendations

Because the LMT01 is only a 2-pin device the power pins are common with the signal pins, thus the LMT01 has a floating supply that can vary greatly. The LMT01 has an internal regulator that provides a stable voltage to internal circuitry.

Take care to prevent reverse biasing of the LMT01 as exceeding the absolute maximum ratings may cause damage to the device.

Power supply ramp rate can effect the accuracy of the first result transmitted by the LMT01. As shown in Figure 36 with a 1-ms rise time, the LMT01 output code is at 1286, which converts to 30.125°C. The scope photo shown in Figure 37 reflects what happens when the rise time is too slow. In Figure 37, the power supply (yellow trace) is still ramping up to final value while the LMT01 (red trace) has already started a conversion. This causes the output pulse count to decrease from the previously shown 1286, to 1282 (or 29.875°C). Thus, for slow ramp rates, TI recommends that the first conversion be discarded. For even slower ramp rates, more than one conversion may have to be discarded as TI recommends that either the power supply be within final value before a conversion is used or that ramp rates be faster than 2.5 ms.

LMT01 LMT01_RR_3V_1ms_30C.jpg
Yellow trace = 1 V/div, Red trace = 100 mV/div, Time Base = 20 ms/div
TA= 30°C LMT01 Pulse Count = 1286
VP-VN = 3.3 V Rise Time = 1 ms
Figure 36. Output Pulse Count With Appropriate Power Supply Rise Time
LMT01 LMT01_RR_3V_100ms_30C.jpg
Yellow trace = 1V/div, Red trace = 100 mV/div, Time base = 20 ms/div
TA=30°C LMT01 Pulse Count = 1282
VP-VN=3.3 V Rise Time = 100 ms
Figure 37. Output Pulse Count With Slow Power Supply Rise Time