TIDUFF0 December   2025

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Key System Specifications
  8. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 AWR2188
      2. 2.3.2 DS90UB971S-Q1
      3. 2.3.3 MSPM0G3519-Q1
      4. 2.3.4 LM68635-Q1
      5. 2.3.5 LP8772x-Q1
      6. 2.3.6 TPS6285018A-Q1
      7. 2.3.7 CDC6C025000-Q1
  9. 3System Design Theory
    1. 3.1 Diagnostic and Monitoring Features
    2. 3.2 Power over Coax (PoC) Network
    3. 3.3 SPI and I2C Communication Interface
  10. 4Hardware, Software, Testing Requirements, and Test Results
    1. 4.1 Hardware Requirements
    2. 4.2 Software Requirements
    3. 4.3 Test Setup
      1. 4.3.1 Precautions
      2. 4.3.2 Data Capturing Approach
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
        1. 5.1.3.1 Launch on Package (LOP Antenna)
        2. 5.1.3.2 Power over Coax (PoC)
        3. 5.1.3.3 PCB Layer Stackup
        4. 5.1.3.4 Board Photos
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
      1. 5.5.1 About the Author
  12. 6About the Author

LM68635-Q1

The LM686x5-Q1 are a family of automotive buck converters designed for high efficiency, high power density, and ultra-low electromagnetic interference (EMI). The converters operate over a wide input voltage range of 3V to 70V (75V tolerant) reducing the need for external input surge protection. The LM686x5-Q1 comes with pin selectable fixed output voltages of 3.3V and 5V or in adjustable configuration. The low EMI operation is enabled with minimized loop inductance and optimized switch node slew rate. The current-mode control architecture with a 30ns typical minimum on-time allows high conversion ratios at high frequencies coupled with a fast transient response and excellent load and line regulation.

The LM686x5-Q1 buck converters are specifically intended for functional safety relevant applications. An array of safety features including ABIST at start-up, redundant and fast VOUT monitoring, feedback path failure detection, redundant temperature sensor, thermal shutdown, and current limiting significantly reduce the residual failure-in-time (FIT).