SNVS896B August   2013  – November 2014 LM27403

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Description (Continued)
  6. 6 Pin Configuration and Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 Handling Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Input Range: VIN
      2. 8.3.2  Output Voltage: FB Voltage and Accuracy
      3. 8.3.3  Input and Bias Rail Voltages: VIN and VDD
      4. 8.3.4  Precision Enable: UVLO/EN
      5. 8.3.5  Switching Frequency
        1. 8.3.5.1 Frequency Adjust: FADJ
        2. 8.3.5.2 Clock Synchronization: SYNC
      6. 8.3.6  Temperature Sensing: D+ and D-
      7. 8.3.7  Thermal Shutdown: OTP
      8. 8.3.8  Inductor-DCR-Based Overcurrent Protection
      9. 8.3.9  Current Sensing: CS+ and CS-
      10. 8.3.10 Current Limit Handling
      11. 8.3.11 Soft-Start: SS/TRACK
        1. 8.3.11.1 Tracking
      12. 8.3.12 Monotonic Startup
      13. 8.3.13 Prebias Startup
      14. 8.3.14 Voltage-Mode Control
      15. 8.3.15 Output Voltage Remote Sense: RS
      16. 8.3.16 Power Good: PGOOD
      17. 8.3.17 Gate Drivers: LG and HG
      18. 8.3.18 Sink and Source Capability
    4. 8.4 Device Functional Modes
      1. 8.4.1 Fault Conditions
        1. 8.4.1.1 Thermal Shutdown
        2. 8.4.1.2 Current Limit and Short Circuit Operation (Positive Overcurrent)
        3. 8.4.1.3 Negative Current Limit
        4. 8.4.1.4 Undervoltage Threshold (UVT)
        5. 8.4.1.5 Overvoltage Threshold (OVT)
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Design and Implementation
      2. 9.1.2 Power Train Components
        1. 9.1.2.1 Filter Inductor
        2. 9.1.2.2 Output Capacitors
        3. 9.1.2.3 Input Capacitors
        4. 9.1.2.4 Power MOSFETs
      3. 9.1.3 Control Loop Compensation
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1 - High-Efficiency Synchronous Buck Regulator for Telecom Power
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2 - Powering FPGAs Using Flexible 30A Regulator With Small Footprint
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Design 3 - Powering Multicore DSPs
      4. 9.2.4 Design 4 - Regulated 12-V Rail with LDO Low-Noise Auxiliary Output for RF Power
      5. 9.2.5 Design 5 - High Power Density Implementation From 3.3-V or 5-V Supply Rail
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Power Stage Layout
      2. 11.1.2 Gate Drive Layout
      3. 11.1.3 Controller Layout
      4. 11.1.4 Thermal Design and Layout
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
      2. 12.1.2 Third-Party Products Disclaimer
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

1 Features

  • Up to 97% Efficiency and 93% Duty Cycle
  • Wide Input Voltage Range of 3 V to 20 V
  • Switching Frequency From 200 kHz to 1.2 MHz
  • Inductor-DCR-Based Overcurrent Protection With Thermal Compensation
  • 0.6-V Reference With 1% Feedback Accuracy
  • 30-ns Min On-Time for Low VOUT
  • Integrated High-Current MOSFET Drivers
    • Adaptive Deadtime Control
  • Ultrafast Line and Load Transient Response
    • High GBW Error Amplifier
    • PWM Line Feedforward
  • Integrated VDD Bias Supply LDO Subregulator
  • Programmable System-Level OTP
  • Precision Enable With Hysteresis
  • Frequency Synchronization
  • Monotonic Prebiased Start-up
  • Programmable Soft-Start With Tracking
  • Output Remote Sense
  • Open-Drain Power Good Indicator
  • 4-mm x 4-mm WQFN-24 PowerPAD™ Package

2 Applications

  • DC-DC Converters and POL Modules
  • Telecommunications Infrastructure
  • Embedded Computing, Servers, Storage

3 Description

The LM27403 is a feature-rich, easy-to-use, synchronous buck controller offering exceptional levels of integration and performance for superior efficiency in high power density, point-of-load (POL) DC-DC regulator solutions. The resistor-programmable switching frequency from 200 kHz to 1.2 MHz and integrated, high-current MOSFET gate drivers with adaptive deadtime offer flexibility to optimize solution size and maximize conversion efficiency.

High precision and low output voltage are easily obtained with a 0.6-V, 1% accurate voltage reference together with a 30-ns high-side MOSFET minimum controllable on-time. Using lossless inductor dc resistance (DCR) current sensing and an inexpensive 2N3904 BJT to sense temperature remotely at the inductor, the LM27403 supports accurate and thermally compensated overcurrent protection (OCP).

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM27403 WQFN (24) 4.00 mm x 4.00 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Typical Application Diagram

Typ_app_circuit_nvs896.gif