SNVSAH5A September   2017  – May 2020 LM73605 , LM73606

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Efficiency versus Load Current VOUT = 5 V, fSW = 500 kHz, Auto Mode
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Electrical Characteristics
    6. 6.6 Timing Characteristics
    7. 6.7 Switching Characteristics
    8. 6.8 System Characteristics
    9. 6.9 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Synchronous Step-Down Regulator
      2. 7.3.2  Auto Mode and FPWM Mode
      3. 7.3.3  Fixed-Frequency Peak Current-Mode Control
      4. 7.3.4  Adjustable Output Voltage
      5. 7.3.5  Enable and UVLO
      6. 7.3.6  Internal LDO, VCC_UVLO, and BIAS Input
      7. 7.3.7  Soft Start and Voltage Tracking
      8. 7.3.8  Adjustable Switching Frequency
      9. 7.3.9  Frequency Synchronization and Mode Setting
      10. 7.3.10 Internal Compensation and CFF
      11. 7.3.11 Bootstrap Capacitor and VBOOT-UVLO
      12. 7.3.12 Power-Good and Overvoltage Protection
      13. 7.3.13 Overcurrent and Short-Circuit Protection
      14. 7.3.14 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Active Mode
        1. 7.4.3.1 CCM Mode
        2. 7.4.3.2 DCM Mode
        3. 7.4.3.3 PFM Mode
        4. 7.4.3.4 Fault Protection Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Custom Design With WEBENCH® Tools
        2. 8.2.2.2  Output Voltage Setpoint
        3. 8.2.2.3  Switching Frequency
        4. 8.2.2.4  Input Capacitors
        5. 8.2.2.5  Inductor Selection
        6. 8.2.2.6  Output Capacitor Selection
        7. 8.2.2.7  Feedforward Capacitor
        8. 8.2.2.8  Bootstrap Capacitors
        9. 8.2.2.9  VCC Capacitor
        10. 8.2.2.10 BIAS
        11. 8.2.2.11 Soft Start
        12. 8.2.2.12 Undervoltage Lockout Setpoint
        13. 8.2.2.13 PGOOD
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Layout For EMI Reduction
      2. 10.1.2 Ground Plane
      3. 10.1.3 Optimize Thermal Performance
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Related Links
    4. 11.4 Receiving Notification of Documentation Updates
    5. 11.5 Support Resources
    6. 11.6 Trademarks
    7. 11.7 Electrostatic Discharge Caution
    8. 11.8 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.1 Overview

The LM73605 and LM73606are easy-to-use synchronous step-down DC/DC converters that operate from a 3.5-V to 36-V supply voltage. It is capable of delivering up to 5-A (LM73605) or 6-A (LM73606) DC load current with exceptional efficiency and thermal performance in a very small solution size.

The LM73605 and LM73606employs fixed-frequency peak current-mode control with configurable auto or FPWM operation mode. Auto mode provides very high efficiency at light loads, and FPWM mode maintains constant switching frequency over entire load range.

The device is internally compensated, which reduces design time and the number of external components. The switching frequency is programmable from 350 kHz to 2.2 MHz by an external resistor. The LM73605 and LM73606 can also synchronize to an external clock within the same frequency range. The wide switching frequency range allows the device to be optimized for a wide range of system requirements. It can be optimized for small solution size with higher frequency; or for high efficiency with lower switching frequency. The LM73605 and LM73606have very low quiescent current, which is critical for battery-operated systems. It allows for a wide range of voltage conversion ratios due to very small minimum on-time (tON-MIN) and minimum off-time (tOFF-MIN). Automated frequency foldback is employed at very high or low duty cycles to further extend the operating range.

The LM73605 and LM73606 also feature a power-good (PGOOD) flag, precision enable, internal or adjustable soft start, pre-biased start-up, and output voltage tracking. Protection features include thermal shutdown, undervoltage lockout (UVLO), cycle-by-cycle current limiting, and short-circuit hiccup protection. It provides flexible and easy-to-use solutions for a wide range of applications.

The family requires very few external components and has a pin out designed for simple, optimum PCB layout for enhanced EMI and thermal performance. The LM73605 and LM73606 devices are available in a 30-pin WQFN leadless package.