SNVS954H February   2013  – June 2017 LM5122

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings: LM5122, LM5122Z
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 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  Undervoltage Lockout (UVLO)
      2. 7.3.2  High Voltage VCC Regulator
      3. 7.3.3  Oscillator
      4. 7.3.4  Slope Compensation
      5. 7.3.5  Error Amplifier
      6. 7.3.6  PWM Comparator
      7. 7.3.7  Soft-Start
      8. 7.3.8  HO and LO Drivers
      9. 7.3.9  Bypass Operation (VOUT = VIN)
      10. 7.3.10 Cycle-by-Cycle Current Limit
      11. 7.3.11 Clock Synchronization
      12. 7.3.12 Maximum Duty Cycle
      13. 7.3.13 Thermal Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 MODE Control (Forced-PWM Mode and Diode-Emulation Mode)
      2. 7.4.2 MODE Control (Skip-Cycle Mode and Pulse-Skipping Mode)
      3. 7.4.3 Hiccup-Mode Overload Protection
      4. 7.4.4 Slave Mode and SYNCOUT
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Feedback Compensation
      2. 8.1.2 Sub-Harmonic Oscillation
      3. 8.1.3 Interleaved Boost Configuration
      4. 8.1.4 DCR Sensing
      5. 8.1.5 Output Overvoltage Protection
      6. 8.1.6 SEPIC Converter Simplified Schematic
      7. 8.1.7 Non-Isolated Synchronous Flyback Converter Simplified Schematic
      8. 8.1.8 Negative to Positive Conversion
    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  Timing Resistor RT
        3. 8.2.2.3  UVLO Divider RUV2, RUV1
        4. 8.2.2.4  Input Inductor LIN
        5. 8.2.2.5  Current Sense Resistor RS
        6. 8.2.2.6  Current Sense Filter RCSFP, RCSFN, CCS
        7. 8.2.2.7  Slope Compensation Resistor RSLOPE
        8. 8.2.2.8  Output Capacitor COUT
        9. 8.2.2.9  Input Capacitor CIN
        10. 8.2.2.10 VIN Filter RVIN, CVIN
        11. 8.2.2.11 Bootstrap Capacitor CBST and Boost Diode DBST
        12. 8.2.2.12 VCC Capacitor CVCC
        13. 8.2.2.13 Output Voltage Divider RFB1, RFB2
        14. 8.2.2.14 Soft-Start Capacitor CSS
        15. 8.2.2.15 Restart Capacitor CRES
        16. 8.2.2.16 Low-Side Power Switch QL
        17. 8.2.2.17 High-Side Power Switch QH and Additional Parallel Schottky Diode
        18. 8.2.2.18 Snubber Components
        19. 8.2.2.19 Loop Compensation Components CCOMP, RCOMP, CHF
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Development Support
        1. 11.1.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Community Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

1 Features

  • Maximum Input Voltage: 65 V
  • Minimum Input Voltage: 3 V (4.5 V for Start-Up)
  • Output Voltage up to 100 V
  • Bypass (VOUT = VIN) Operation
  • 1.2-V Reference with ±1% Accuracy
  • Free-Run and Synchronizable Switching to 1 MHz
  • Peak-Current-Mode Control
  • Robust 3-A Integrated Gate Drivers
  • Adaptive Dead-Time Control
  • Optional Diode-Emulation Mode
  • Programmable Cycle-by-Cycle Current Limit
  • Hiccup-Mode Overload Protection
  • Programmable Line UVLO
  • Programmable Soft Start
  • Thermal Shutdown Protection
  • Low Shutdown Quiescent Current: 9 μA
  • Programmable Slope Compensation
  • Programmable Skip-Cycle Mode Reduces Standby Power
  • Allows External VCC Supply
  • Inductor DCR Current Sensing Capability
  • Multi-phase Capability
  • Thermally Enhanced 20 or 24-Pin HTSSOP
  • Create a Custom Design Using the LM5122 With the WEBENCH® Power Designer

2 Applications

  • 12-V, 24-V, and 48-V Power Systems
  • Automotive Start-Stop
  • Audio Power Supply
  • High-Current Boost Power Supply

3 Description

The LM5122 is a multi-phase capable synchronous boost controller intended for high-efficiency synchronous boost regulator applications. The control method is based upon peak-current-mode control. Current-mode control provides inherent line feed forward, cycle-by-cycle current limiting, and ease of loop compensation.

The switching frequency is programmable up to 1 MHz. Higher efficiency is achieved by two robust N-channel MOSFET gate drivers with adaptive dead-time control. A user-selectable diode-emulation mode also enables discontinuous-mode operation for improved efficiency at light load conditions.

An internal charge pump allows 100% duty cycle for high-side synchronous switch (bypass operation). A 180° phase shifted clock output enables easy multi-phase interleaved configuration. Additional features include thermal shutdown, frequency synchronization, hiccup-mode current limit, and adjustable line undervoltage lockout.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM5122 HTSSOP (20) 6.50 mm × 4.40 mm
LM5122Z HTSSOP (24) 7.80 mm × 4.40 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

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Simplified Application Diagram

LM5122 Simplified_Schematic.gif