SNIS144G July   2007  – September 2016 LM26LV , LM26LV-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings: LM26LV
    3. 6.3 ESD Ratings: LM26LV-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 Switching Characteristics
    8. 6.8 Accuracy Characteristics
    9. 6.9 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 LM26LV and LM26LV-Q1 VTEMP vs Die Temperature Conversion Table
      2. 7.3.2 VTEMP vs Die Temperature Approximations
        1. 7.3.2.1 The Second-Order Equation (Parabolic)
        2. 7.3.2.2 The First-Order Approximation (Linear)
        3. 7.3.2.3 First-Order Approximation (Linear) Over Small Temperature Range
      3. 7.3.3 OVERTEMP and OVERTEMP Digital Outputs
        1. 7.3.3.1 OVERTEMP Open-Drain Digital Output
          1. 7.3.3.1.1 Determining the Pullup Resistor Value
            1. 7.3.3.1.1.1 Example Calculation
      4. 7.3.4 TRIP_TEST Digital Input
      5. 7.3.5 VTEMP Analog Temperature Sensor Output
        1. 7.3.5.1 Noise Considerations
        2. 7.3.5.2 Capacitive Loads
        3. 7.3.5.3 Voltage Shift
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 ADC Input Considerations
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Power Supply Noise Immunity
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Mounting and Temperature Conductivity
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Related Links
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

10 Layout

10.1 Layout Guidelines

10.1.1 Mounting and Temperature Conductivity

The LM26LV or LM26LV-Q1 can be applied easily in the same way as other integrated-circuit temperature sensors. The devices can be glued or cemented to a surface.

The best thermal conductivity between the device and the PCB is achieved by soldering the DAP of the package to the thermal pad on the PCB. The temperatures of the lands and traces to the other leads of the LM26LV and LM26LV-Q1 also affect the temperature reading.

Alternatively, the LM26LV or LM26LV-Q1 can be mounted inside a sealed-end metal tube, and can then be dipped into a bath or screwed into a threaded hole in a tank. As with any IC, the LM26LV or LM26LV-Q1 and accompanying wiring and circuits must be kept insulated and dry, to avoid leakage and corrosion. This is especially true if the circuit may operate at cold temperatures where condensation can occur. If moisture creates a short circuit from the VTEMP output to ground or VDD, the VTEMP output from the LM26LV or LM26LV-Q1 is not correct. Printed-circuit coatings are often used to ensure that moisture cannot corrode the leads or circuit traces.

The thermal resistance junction-to-ambient (RθJA) is the parameter used to calculate the rise of a device junction temperature due to its power dissipation. The equation used to calculate the rise in the LM26LV's and LM26LV-Q1's die temperature is

Equation 9. LM26LV LM26LV-Q1 20204712.gif

where

  • TA is the ambient temperature
  • IQ is the quiescent current
  • IL is the load current on the output
  • VO is the output voltage

For example, in an application where TA = 30°C, VDD = 5 V, IDD = 9 µA, Gain 4, VTEMP = 2231 mV, and IL = 2 µA, the junction temperature would be 30.021°C, showing a self-heating error of only 0.021°C. Because the LM26LV's and LM26LV-Q1's junction temperature is the actual temperature being measured, minimize the load current that the VTEMP output is required to drive. If OVERTEMP is used with a 100‑k pullup resistor, and is asserted (low), then for this example the additional contribution is (152°C/W) × (5 V)2 / 100 kΩ = 0.038°C for a total self-heating error of 0.059°C. Thermal Information shows the thermal resistance of the LM26LV and LM26LV-Q1.

10.2 Layout Example

LM26LV LM26LV-Q1 Layout01_SNIS144.gif Figure 30. Typical Layout Example
LM26LV LM26LV-Q1 Layout02_Latching_SNIS144.gif Figure 31. Latching Layout Example