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

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.

8.1 Application Information

8.1.1 ADC Input Considerations

The LM26LV and LM26LV-Q1 have an analog temperature sensor output VTEMP that can be directly connected to an ADC (Analog-to-Digital Converter) input. Most CMOS ADCs found in microcontrollers and ASICs have a sampled data comparator input structure. When the ADC charges the sampling cap, it requires instantaneous charge from the output of the analog source such as the LM26LV or LM26LV-Q1 temperature sensor. This requirement is easily accommodated by the addition of a capacitor (CFILTER). The size of CFILTER depends on the size of the sampling capacitor and the sampling frequency. Because not all ADCs have identical input stages, the charge requirements vary. This general ADC application is shown as an example only.

LM26LV LM26LV-Q1 20204728.gif Figure 26. Suggested Connection to a Sampling Analog-to-Digital Converter Input Stage

8.2 Typical Application

LM26LV LM26LV-Q1 20204702.gif Figure 27. Typical Application Schematic

8.2.1 Design Requirements

For this design example, use the parameters listed in Table 3 as the input parameters.

Table 3. Design Parameters

PARAMETER EXAMPLE VALUE
Temperature 0°C to 150°C (LM26LV), –40°C to 85°C for microcontroller
Accuracy ±2.3°C (Gain1, TA = 0°C to 150°C)
VDD 3.3 V
IDD 8 µA

8.2.2 Detailed Design Procedure

The LM26LV and LM26LV-Q1 come with a factory preset trip point. See Mechanical, Packaging, and Orderable Information for available trip point options. Figure 27 shows the device's OVERTEMP output driving a microcontroller interrupt input to indicate an overtemperature event. In addition to the OVERTEMP output, a OVERTEMP output is available for use depending on the interrupt polarity of the microcontroller's interrupt pin. A VTEMP analog output is available to drive the microcontroller ADC input allowing the microcontroller to determine the sensing temperature of the LM26LV or LM26LV-Q1. The TRIP_TEST input is connected to a microcontroller output pin allowing the microcontroller to run on the fly electrical conductivity testing. For normal operation TRIP_TEST must be driven low by the microcontroller output. If no testing is required, the TRIP_TEST pin may be continuously grounded.

8.2.3 Application Curves

LM26LV LM26LV-Q1 20204707.png Figure 28. VTEMP Analog Output Temperature Error
LM26LV LM26LV-Q1 TypAppCurve_SNIS144.gif Figure 29. Switch Output Function