SNVS593J October   2008  – November 2014 LM25085 , LM25085-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 Handling Ratings - LM25085
    3. 6.3 Handling Ratings - LM25085-Q1
    4. 6.4 Recommended Operating Conditions
    5. 6.5 Thermal Information
    6. 6.6 Electrical Characteristics
    7. 6.7 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  Regulation Control Circuit
      2. 7.3.2  On-Time Timer
      3. 7.3.3  Shutdown
      4. 7.3.4  Current Limiting
      5. 7.3.5  Current Limit Off-Time
      6. 7.3.6  VCC Regulator
      7. 7.3.7  PGATE Driver Output
      8. 7.3.8  P-Channel MOSFET Selection
      9. 7.3.9  Soft-Start
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Standby Mode with VIN <4.5 V
      2. 7.4.2 RT Shutdown 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  RFB1 and RFB2
        2. 8.2.2.2  RT, PFET
        3. 8.2.2.3  L1
        4. 8.2.2.4  RSEN, RADJ
        5. 8.2.2.5  COUT
        6. 8.2.2.6  R3, C1, C2
        7. 8.2.2.7  Alternate Output Ripple Configurations
          1. 8.2.2.7.1 Reduced Ripple Configuration
          2. 8.2.2.7.2 Lowest Cost Configuration
        8. 8.2.2.8  CIN, CBYP
        9. 8.2.2.9  D1
        10. 8.2.2.10 CVCC
        11. 8.2.2.11 IC Power Dissipation
      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 Third-Party Products Disclaimer
    2. 11.2 Related Links
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • LM25085-Q1 is an Automotive Grade product that is AEC-Q100 Grade 1 Qualified (-40°C to 125°C Operating Junction Temperature)
  • Wide 4.5V to 42V Input Voltage Range
  • Adjustable Current Limit Using RDS(ON) or a Current Sense Resistor
  • Programmable Switching Frequency to 1MHz
  • No Loop Compensation Required
  • Ultra-Fast Transient Response
  • Nearly Constant Operating Frequency with Line and Load Variations
  • Adjustable Output Voltage from 1.25V
  • Precision ±2% Feedback Reference
  • Capable of 100% Duty Cycle Operation
  • Internal Soft-Start Timer
  • Integrated High Voltage Bias Regulator
  • Thermal Shutdown

2 Applications

  • Automotive Infotainment
  • Battery/Super Capacitor Chargers
  • LED Drivers

3 Description

The LM25085 is a high efficiency PFET switching regulator controller that can be used to quickly and easily develop a small, efficient buck regulator for a wide range of applications. This high voltage controller contains a PFET gate driver and a high voltage bias regulator which operates over a wide 4.5V to 42V input range. The constant on-time regulation principle requires no loop compensation, simplifies circuit implementation, and results in ultra-fast load transient response. The operating frequency remains nearly constant with line and load variations due to the inverse relationship between the input voltage and the on-time. The PFET architecture allows 100% duty cycle operation for a low dropout voltage. Either the RDS(ON) of the PFET or an external sense resistor can be used to sense current for over-current detection.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
LM25085-Q1 HVSSOP (8) 3.00 mm x 3.00 mm
LM25085 VSSOP (8) 3.00 mm x 3.00 mm
WSON (8) 3.00 mm x 3.00 mm
HVSSOP (8) 3.00 mm x 3.00 mm
  1. For all available packages, see the orderable addendum at the end of the datasheet.

Simplified Schematic

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