SNOSB29H November   2009  – May 2022 LMP8645 , LMP8645HV

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
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 2.7-V Electrical Characteristics
    6. 6.6 5-V Electrical Characteristics
    7. 6.7 12-V Electrical Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
      1. 7.1.1 Theory of Operation
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Driving ADC
      2. 7.3.2 Applying Input Voltage With No Supply Voltage
    4. 7.4 Device Functional Modes
      1. 7.4.1 Selection of the Gain Resistor
      2. 7.4.2 Gain Range Limitations
        1. 7.4.2.1 Range 1: VCM is –2 V to 1.8 V
        2. 7.4.2.2 Range 2: VCM is 1.8 V to VS
        3. 7.4.2.3 Range 3: VCM is greater than VS
      3. 7.4.3 Selection of Sense Resistor
        1. 7.4.3.1 Resistor Power Rating and Thermal Issues
        2. 7.4.3.2 Using PCB Trace as a Sense Resistor
      4. 7.4.4 Sense Line Inputs
        1. 7.4.4.1 Effects of Series Resistance on Sense Lines
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Typical Current Monitor Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
        3. 8.2.1.3 Application Curves
      2. 8.2.2 High Brightness LED Driver
  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 Device Support
      1. 11.1.1 Development Support
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support 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

7.4.2 Gain Range Limitations

The gain resistor must be chosen such that the theoretical maximum output voltage does not exceed the LMP8645 maximum output voltage rating for a given common-mode voltage. These limits are due to the internal amplifier bias point and the VCM headroom required to generate the required currents across the RIN and RGAIN resistors.

The following sections explain how to select the gain resistor for various ranges of the input common-mode voltage.