SNVSCU2A August   2024  – August 2024 LM5137-Q1

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
    1. 5.1 Wettable Flanks
  7. 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 Electrical Characteristics
    6. 6.6 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Input Voltage Range (VIN)
      2. 7.3.2  Bias Supply Regulator (VCC, BIAS1/VOUT1, VDDA)
      3. 7.3.3  Precision Enable (EN1, EN2)
      4. 7.3.4  Switching Frequency (RT)
      5. 7.3.5  Pulse Frequency Modulation and Synchronization (PFM/SYNC)
      6. 7.3.6  Synchronization Out (SYNCOUT)
      7. 7.3.7  Dual Random Spread Spectrum (DRSS)
      8. 7.3.8  Configurable Soft Start (RSS)
      9. 7.3.9  Output Voltage Setpoints (FB1, FB2)
      10. 7.3.10 Minimum Controllable On-Time
      11. 7.3.11 Error Amplifier and PWM Comparator (FB1, FB2, COMP1, COMP2)
        1. 7.3.11.1 Slope Compensation
      12. 7.3.12 Inductor Current Sense (ISNS1+, BIAS1/VOUT1, ISNS2+, VOUT2)
        1. 7.3.12.1 Shunt Current Sensing
        2. 7.3.12.2 Inductor DCR Current Sensing
      13. 7.3.13 MOSFET Gate Drivers (HO1, HO2, LO1, LO2)
      14. 7.3.14 Output Configurations (CNFG)
        1. 7.3.14.1 Independent Dual-Output Operation
        2. 7.3.14.2 Single-Output Interleaved Operation
        3. 7.3.14.3 Single-Output Multiphase Operation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Sleep Mode
      2. 7.4.2 PFM Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Power Train Components
        1. 8.1.1.1 Power MOSFETs
        2. 8.1.1.2 Buck Inductor
        3. 8.1.1.3 Output Capacitors
        4. 8.1.1.4 Input Capacitors
        5. 8.1.1.5 EMI Filter
      2. 8.1.2 Error Amplifier and Compensation
    2. 8.2 Typical Applications
      1. 8.2.1 Design 1 – Dual 5V and 3.3V, 20A Buck Regulator for 12V Automotive Battery Applications
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2 Custom Design With Excel Quickstart Tool
          3. 8.2.1.2.3 Inductor Calculations
          4. 8.2.1.2.4 Shunt Resistors
          5. 8.2.1.2.5 Ceramic Output Capacitors
          6. 8.2.1.2.6 Ceramic Input Capacitors
          7. 8.2.1.2.7 Feedback Resistors
          8. 8.2.1.2.8 Input Voltage UVLO Resistors
          9. 8.2.1.2.9 Compensation Components
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Design 2 – Two-Phase, Single-Output Buck Regulator for Automotive ADAS Applications
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
      3. 8.2.3 Design 3 – 12V, 20A, 400kHz, Two-Phase Buck Regulator for 48V Automotive Applications
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
        3. 8.2.3.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Power Stage Layout
        2. 8.4.1.2 Gate Drive Layout
        3. 8.4.1.3 PWM Controller Layout
        4. 8.4.1.4 Thermal Design and Layout
        5. 8.4.1.5 Ground Plane Design
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 Third-Party Products Disclaimer
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 Documentation Support
      1. 9.2.1 Related Documentation
        1. 9.2.1.1 PCB Layout Resources
        2. 9.2.1.2 Thermal Design Resources
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
    1. 11.1 Tape and Reel Information

Package Options

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

3 Description

The LM5137-Q1 is an 80V synchronous buck DC/DC controller offered from a family with three options for functional safety: Capable, ASIL B, or ASIL D. The device uses an interleaved, stackable, peak current-mode architecture for easy loop compensation, fast transient response, excellent load and line regulation, and accurate current sharing with paralleled phases for high output current.

A high-side switch minimum on-time of 15ns facilitates large step-down ratios, enabling the direct conversion from 12V, 24V or 48V automotive inputs to low-voltage rails for reduced system design cost and complexity. The LM5137-Q1 continues to operate during input voltage dips as low as 4V, at 100% duty cycle if needed. The 12.7μA no-load quiescent current with the output voltage in regulation extends operating run-time in battery-powered automotive systems.

Package Information
PART NUMBER PACKAGE(1) PACKAGE SIZE(2)
LM5137-Q1 RHA (VQFN, 36) 6.0mm × 6.0mm
(1) For more information, see Section 11.
(2) The package size (length × width) is a nominal value and includes pins, where applicable.
LM5137-Q1 LM5137-Q1 Dual-Output Buck Switching Regulator – Simplified Schematic LM5137-Q1 Dual-Output Buck Switching Regulator – Simplified Schematic

Several features are included to simplify compliance with CISPR 25 and automotive EMI requirements. Adaptively timed, high-current MOSFET gate drivers minimize body diode conduction during switching transitions, reducing switching losses and improving thermal and EMI performance at high input voltage and high switching frequency. To reduce input capacitor ripple current and EMI filter size, 180° interleaved operation is provided for two outputs. A 90° out-of-phase clock output works well for cascaded, multi-channel or multiphase power stages. Resistor-adjustable switching frequency as high as 2.2MHz can be synchronized to an external clock source up to 2.5MHz to eliminate beat frequencies in noise-sensitive applications.

Additional features of the LM5137-Q1 include 150°C maximum junction temperature operation, user-selectable PFM mode for lower current consumption at light-load conditions, configurable soft-start functions, open-drain PG flags for fault reporting and output monitoring, independent enable inputs, monotonic start-up into prebiased loads, integrated VCC bias supply regulator powered from VIN or BIAS1/VOUT1, hiccup-mode overload protection, and thermal shutdown protection with automatic recovery. Current is sensed using the inductor DCR for highest efficiency or an optional shunt resistor for high accuracy.

The LM5137-Q1 controller is qualified to AEC-Q100 grade 1 for automotive applications and comes in a 6mm × 6mm thermally-enhanced, 36-pin VQFN package with additional pin clearance for increased reliability and wettable flank pins to facilitate optical inspection during manufacturing. The wide input voltage range, low quiescent current consumption, high-temperature operation, cycle-by-cycle current limit, low EMI signature, and small design size provide an excellent point-of-load regulator solution for applications requiring enhanced robustness and durability.