SNVSAF0B December   2015  – May 2016 LM25122-Q1

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
    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 Over-Load 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
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Timing Resistor RT
        2. 8.2.2.2  UVLO Divider RUV2, RUV1
        3. 8.2.2.3  Input Inductor LIN
        4. 8.2.2.4  Current Sense Resistor RS
        5. 8.2.2.5  Current Sense Filter RCSFP, RCSFN, CCS
        6. 8.2.2.6  Slope Compensation Resistor RSLOPE
        7. 8.2.2.7  Output Capacitor COUT
        8. 8.2.2.8  Input Capacitor CIN
        9. 8.2.2.9  VIN Filter RVIN, CVIN
        10. 8.2.2.10 Bootstrap Capacitor CBST and Boost Diode DBST
        11. 8.2.2.11 VCC Capacitor CVCC
        12. 8.2.2.12 Output Voltage Divider RFB1, RFB2
        13. 8.2.2.13 Soft-Start Capacitor CSS
        14. 8.2.2.14 Restart Capacitor CRES
        15. 8.2.2.15 Low-Side Power Switch QL
        16. 8.2.2.16 High-Side Power Switch QH and Additional Parallel Schottky Diode
        17. 8.2.2.17 Snubber Components
        18. 8.2.2.18 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 Community Resources
    2. 11.2 Trademarks
    3. 11.3 Electrostatic Discharge Caution
    4. 11.4 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • AEC-Q100 Qualified with the following results:
    • Device Temperature Grade 1: -40°C to +125°C Ambient Operating Temperature Range
    • Device HBM ESD Classification Level 2
    • Device CDM ESD Classification Level C6
  • Maximum Input Voltage : 42 V
  • Min Input Voltage : 3 V (4.5 V for startup)
  • Output Voltage up to 50 V
  • Bypass (VOUT = VIN) Operation
  • 1.2 V Reference with ±1.0% Accuracy
  • Free-Run and Synchronizable Switching to 600 kHz
  • 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
  • Multiphase Capability
  • Thermally Enhanced 20-Pin HTSSOP

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 LM25122 is a multiphase 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 600 kHz. 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 180º 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)
LM25122-Q1 HTSSOP (20) 6.50 mm × 4.40 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Application Diagram

LM25122-Q1 Simp_App_Circ_SNVSAF0.gif