SNVSCM3 June   2024 LM5171

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
      1. 6.1.1 Device Configurations (CFG) and I2C Address
      2. 6.1.2 Definition of IC Operation Modes
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1  Bias Supplies and Voltage Reference (VCC, VDD, and VREF)
      2. 6.3.2  Undervoltage Lockout (UVLO) and Controller Enable or Disable
      3. 6.3.3  High Voltage Inputs (HV1, HV2)
      4. 6.3.4  Current Sense Amplifier
      5. 6.3.5  Control Commands
        1. 6.3.5.1 Channel Enable Commands (EN1, EN2)
        2. 6.3.5.2 Direction Command (DIR1 and DIR2)
        3. 6.3.5.3 Channel Current Setting Commands (ISET1 and ISET2)
      6. 6.3.6  Channel Current Monitor (IMON1, IMON2)
        1. 6.3.6.1 Individual Channel Current Monitor
        2. 6.3.6.2 Multiphase Total Current Monitoring
      7. 6.3.7  Cycle-by-Cycle Peak Current Limit (IPK)
      8. 6.3.8  Inner Current Loop Error Amplifier
      9. 6.3.9  Outer Voltage Loop Error Amplifier
      10. 6.3.10 Soft Start, Diode Emulation, and Forced PWM Control (SS/DEM1 and SS/DEM2)
        1. 6.3.10.1 Soft-Start Control by the SS/DEM Pins
        2. 6.3.10.2 DEM Programming
        3. 6.3.10.3 FPWM Programming and Dynamic FPWM and DEM Change
        4. 6.3.10.4 SS Pin as the Restart Timer
          1. 6.3.10.4.1 Restart Timer in OVP
          2. 6.3.10.4.2 Restart Timer after a DIR Change
      11. 6.3.11 Gate Drive Outputs, Dead Time Programming and Adaptive Dead Time (HO1, HO2, LO1, LO2, DT/SD)
      12. 6.3.12 Emergency Latched Shutdown (DT/SD)
      13. 6.3.13 PWM Comparator
      14. 6.3.14 Oscillator (OSC)
      15. 6.3.15 Synchronization to an External Clock (SYNCI, SYNCO)
      16. 6.3.16 Overvoltage Protection (OVP)
      17. 6.3.17 Multiphase Configurations (SYNCO, OPT)
        1. 6.3.17.1 Multiphase in Star Configuration
        2. 6.3.17.2 Daisy-Chain Configurations for 2, 3, or 4 Phases parallel operations
        3. 6.3.17.3 Daisy-Chain configuration for 6 or 8 phases parallel operation
      18. 6.3.18 Thermal Shutdown
    4. 6.4 Programming
      1. 6.4.1 Dynamic Dead Time Adjustment
      2. 6.4.2 UVLO Programming
    5. 6.5 Registers
      1. 6.5.1 I2C Serial Interface
      2. 6.5.2 I2C Bus Operation
      3. 6.5.3 Clock Stretching
      4. 6.5.4 Data Transfer Formats
      5. 6.5.5 Single READ From a Defined Register Address
      6. 6.5.6 Sequential READ Starting From a Defined Register Address
      7. 6.5.7 Single WRITE to a Defined Register Address
      8. 6.5.8 Sequential WRITE Starting From A Defined Register Address
      9. 6.5.9 REGFIELD Registers
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Small Signal Model
        1. 7.1.1.1 Current Loop Small Signal Model
        2. 7.1.1.2 Current Loop Compensation
        3. 7.1.1.3 Voltage Loop Small Signal Model
        4. 7.1.1.4 Voltage Loop Compensation
    2. 7.2 Typical Application
      1. 7.2.1 60A, Dual-Phase, 48V to 12V Bidirectional Converter
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1  Determining the Duty Cycle
          2. 7.2.1.2.2  Oscillator Programming
          3. 7.2.1.2.3  Power Inductor, RMS and Peak Currents
          4. 7.2.1.2.4  Current Sense (RCS)
          5. 7.2.1.2.5  Current Setting Limits (ISETx)
          6. 7.2.1.2.6  Peak Current Limit
          7. 7.2.1.2.7  Power MOSFETS
          8. 7.2.1.2.8  Bias Supply
          9. 7.2.1.2.9  Boot Strap
          10. 7.2.1.2.10 OVP
          11. 7.2.1.2.11 Dead Time
          12. 7.2.1.2.12 Channel Current Monitor (IMONx)
          13. 7.2.1.2.13 UVLO Pin Usage
          14. 7.2.1.2.14 HVx Pin Configuration
          15. 7.2.1.2.15 Loop Compensation
          16. 7.2.1.2.16 Soft Start
          17. 7.2.1.2.17 PWM to ISET Pins
          18. 7.2.1.2.18 Proper Termination of Unused Pins
        3. 7.2.1.3 Application Curves
          1. 7.2.1.3.1 Efficiency
          2. 7.2.1.3.2 Step Load Response
          3. 7.2.1.3.3 Dual-Channel Interleaving Operation
          4. 7.2.1.3.4 Typical Start Up and Shutdown
          5. 7.2.1.3.5 DEM and FPWM
          6. 7.2.1.3.6 Mode transition between DEM and FPWM
          7. 7.2.1.3.7 ISET Tracking and PreCharge
          8. 7.2.1.3.8 Protections
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Examples
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Development Support
    2. 8.2 Receiving Notification of Documentation Updates
    3. 8.3 Support Resources
    4. 8.4 Trademarks
    5. 8.5 Electrostatic Discharge Caution
    6. 8.6 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

Package Options

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

6.3.1 Bias Supplies and Voltage Reference (VCC, VDD, and VREF)

The LM5171 integrates a LDO driver to drive an external N-channel MOSFET to generate a 9V bias supply at the VCC pin. The VCC pin can also accept an external supply of 9.5V to 12V and the device turns off the LDO driver to save the power dissipation in the external LDO MOSFET. Figure 6-1 shows typical connections of the bias supply.

When external supply is used, it is recommended to add a block diode to prevent from discharging the VCC during transient in the external supply. If an external supply voltage is greater than 12V, a 10V LDO or switching regulator must be used to produce 10V for VCC. The VCC voltage is directly fed to the low-side MOSFET drivers. A 1μF to 2.2μF ceramic capacitance must be placed between the VCC and PGND pins to bypass the driver switching currents. For the LDO MOSFET, it is recommended to have the Ciss around 300pF or below.

The internal VCC undervoltage (UV) detection circuit monitors the VCC voltage. When the VCC voltage falls below 8V on the falling edge, the LM5171 is held in the shutdown state. For normal operation, the VCC voltage must be greater than 8.5V on the rising edge.

Once the VCC voltage is above the VCC_UV, the VDD and VREF regulator turns on to establish 5.0V and 3.5V, respectively. The VDD regulator can supply up to 10 mA to the external circuit. The VREF is a 1% accurate reference voltage for the external circuit to use, and it has a loading capability of 2mA. A ceramic capacitance between 0.5μF to 2.0uF must be placed between VDD and AGND pins, and 0.1 μF between VREF and AGND pins, respectively.

LM5171 Bias Supplies ConnectionsFigure 6-1 Bias Supplies Connections