SNAS714A November 2016  – September 2017 LMS3635-Q1 , LMS3655-Q1

PRODUCTION DATA. 

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Comparison Tables
  6. Pin Configuration and Functions
  7. Specifications
    1. 7.1Absolute Maximum Ratings
    2. 7.2ESD Ratings
    3. 7.3Recommended Operating Conditions
    4. 7.4Thermal Information
    5. 7.5Thermal Information (for Device Mounted on PCB)
    6. 7.6Electrical Characteristics
    7. 7.7System Characteristics
    8. 7.8Timing Requirements
    9. 7.9Typical Characteristics
  8. Detailed Description
    1. 8.1Overview
    2. 8.2Functional Block Diagram
      1. 8.2.1Control Scheme
    3. 8.3Feature Description
      1. 8.3.1RESET Flag Output
      2. 8.3.2Enable and Start-Up
      3. 8.3.3Soft-Start Function
      4. 8.3.4Current Limit
      5. 8.3.5Hiccup Mode
      6. 8.3.6Synchronizing Input
      7. 8.3.7Undervoltage Lockout (UVLO) and Thermal Shutdown (TSD)
      8. 8.3.8Input Supply Current
    4. 8.4Device Functional Modes
      1. 8.4.1AUTO Mode
      2. 8.4.2FPWM Mode
      3. 8.4.3Dropout
      4. 8.4.4Spread-Spectrum Operation
  9. Application and Implementation
    1. 9.1Application Information
    2. 9.2Typical Applications
      1. 9.2.1General Application
        1. 9.2.1.1Design Requirements
        2. 9.2.1.2Detailed Design Procedure
          1. 9.2.1.2.1External Components Selection
            1. 9.2.1.2.1.1Input Capacitors
            2. 9.2.1.2.1.2Output Inductors and Capacitors
              1. 9.2.1.2.1.2.1Inductor Selection
              2. 9.2.1.2.1.2.2Output Capacitor Selection
          2. 9.2.1.2.2Setting the Output Voltage
          3. 9.2.1.2.3FB for Adjustable Output
          4. 9.2.1.2.4VCC
          5. 9.2.1.2.5BIAS
          6. 9.2.1.2.6CBOOT
          7. 9.2.1.2.7Maximum Ambient Temperature
        3. 9.2.1.3Application Curves
      2. 9.2.2Fixed 5-V Output for USB-Type Applications
        1. 9.2.2.1Design Requirements
        2. 9.2.2.2Detailed Design Procedure
        3. 9.2.2.3Application Curves
      3. 9.2.3Fixed 3.3-V Output
        1. 9.2.3.1Design Requirements
        2. 9.2.3.2Detailed Design Procedure
        3. 9.2.3.3Application Curves
      4. 9.2.46-V Adjustable Output
        1. 9.2.4.1Design Requirements
        2. 9.2.4.2Detailed Design Procedure
        3. 9.2.4.3Application Curves
    3. 9.3Do's and Don't's
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1Layout Guidelines
    2. 11.2Layout Example
  12. 12Device and Documentation Support
    1. 12.1Device Support
      1. 12.1.1Third-Party Products Disclaimer
    2. 12.2Documentation Support
      1. 12.2.1Related Documentation
    3. 12.3Related Links
    4. 12.4Receiving Notification of Documentation Updates
    5. 12.5Community Resources
    6. 12.6Trademarks
    7. 12.7Electrostatic Discharge Caution
    8. 12.8Glossary
  13. 13Mechanical, Packaging, and Orderable Information
    1. 13.1Package Option Addendum
      1. 13.1.1Packaging Information
      2. 13.1.2Tape and Reel Information

Features

  • AEC-Q100 Qualified for Automotive Applications
    • Device Temperature Grade 1: –40°C to +125°C Ambient Operating Temperature
    • Device HBM Classification Level 2
    • Device CDM Classification Level C6
  • 96% Peak Efficiency While Converting 12 V to 5 V
  • Low EMI and Minimized Switch Node Ringing
  • 400-kHz (±10%) Fixed Switching Frequency
  • –40°C to +150°C Junction Temperature Range
  • External Frequency Synchronization
  • RESET Output With Internal Filter and 3-ms Release Timer
  • Automatic Light Load Mode for Improved Efficiency
  • Pin-Selectable Forced PWM Mode
  • Built-In Compensation, Soft Start, Current Limit, Thermal Shutdown, and UVLO
  • 0.35-V Dropout With 3.5-A Load at 25°C (Typical)
  • 18-µA IQ_VIN: Quiescent Current at 3.3 VOUT and No Load (Typical)
  • Output Voltage: 5 V, 3.3 V, and ADJ (1 V to 15 V)
  • ±1.5% Reference Voltage Tolerance

Applications

  • USB Charging
  • Driver Information
  • Surround View Camera
  • Radar/Lidar
  • Vehicle to Vehicle

Description

The LMS3635-Q1 and LMS3655-Q1 synchronous buck regulators are optimized for high performance applications, providing an output voltage of 3.3 V, 5 V, or an adjustable output of 1 V to 15 V. Seamless transition between PWM and PFM modes, along with a low quiescent current, ensures high efficiency and superior transient responses at all loads.

Advanced high-speed circuitry allows the LMS3655-Q1 to regulate an input of 24 V to an output of 3.3 V at a fixed frequency of 400 kHz while also enabling a continuous load current of 5.5 A. An innovative frequency foldback architecture allows this device to regulate a 3.3-V output from an input voltage of only 3.5 V. The input voltage can range up to 36 V, with transient tolerance up to 42 V, easing input surge protection design.

An open-drain reset output, with built-in filtering and delay, provides a true indication of system status. This feature negates the requirement for an additional supervisory component, saving cost and board space.

Device Information(1)

DEVICE NAMEPACKAGEBODY SIZE
LMS3635-Q1SON (22)4.00 mm × 5.00 mm
LMS3655-Q1
  1. For all available packages, see the orderable addendum at the end of the data sheet.

LMS3655-Q1 Conducted EMI:
VOUT = 5 V, IOUT = 5 A

EMI, CISPR, Class 5, automotive LMS3655-Q1 LMS3635-Q1 lf_emi_5a.png

LMS3655-Q1 Efficiency:
VOUT = 5 V

High Efficiency, automotive LMS3655-Q1 LMS3635-Q1 LMS3635-55-tc36-front-page-graph-efficiency-v-output-current-snas701_v2.gif