SNVSBJ0A December   2019  – June 2020 LM5170


  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Simplified Application Circuit
      2.      Channel Current Tracking ISETA Command
  4. Revision History
  5. Description (continued)
  6. Pin Configuration and Functions
    1.     Pin Functions
  7. Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Bias Supply (VCC, VCCA)
      2. 8.3.2  Undervoltage Lockout (UVLO) and Master Enable or Disable
      3. 8.3.3  High Voltage Input (VIN, VINX)
      4. 8.3.4  Current Sense Amplifier
      5. 8.3.5  Control Commands
        1. Channel Enable Commands (EN1, EN2)
        2. Direction Command (DIR)
        3. Channel Current Setting Commands (ISETA or ISETD)
      6. 8.3.6  Channel Current Monitor (IOUT1, IOUT2)
      7. 8.3.7  Cycle-by-Cycle Peak Current Limit (IPK)
      8. 8.3.8  Error Amplifier
      9. 8.3.9  Ramp Generator
      10. 8.3.10 Soft Start
        1. Soft-Start Control by the SS Pin
        2. Soft Start by MCU Through the ISET Pin
        3. The SS Pin as the Restart Timer
      11. 8.3.11 Gate Drive Outputs, Dead Time Programming and Adaptive Dead Time (HO1, HO2, LO1, LO2, DT)
      12. 8.3.12 PWM Comparator
      13. 8.3.13 Oscillator (OSC)
      14. 8.3.14 Synchronization to an External Clock (SYNCIN, SYNCOUT)
      15. 8.3.15 Diode Emulation
      16. 8.3.16 Power MOSFET Failure Detection and Failure Protection (nFAULT, BRKG, BRKS)
        1. Failure Detection Selection at the SYNCOUT Pin
        2. Nominal Circuit Breaker Function
      17. 8.3.17 Overvoltage Protection (OVPA, OVPB)
        1. HV-V- Port OVP (OVPA)
        2. LV-Port OVP (OVPB)
    4. 8.4 Device Functional Modes
      1. 8.4.1 Multiphase Configurations (SYNCOUT, OPT)
        1. Multiphase in Star Configuration
        2. Configuration of 2, 3, or 4 Phases in Master-Slave Daisy-Chain Configurations
        3. Configuration of 6 or 8 Phases in Master-Slave Daisy-Chain Configurations
      2. 8.4.2 Multiphase Total Current Monitoring
    5. 8.5 Programming
      1. 8.5.1 Dynamic Dead Time Adjustment
      2. 8.5.2 Optional UVLO Programming
  9. Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Typical Key Waveforms
        1. Typical Power-Up Sequence
        2. One to Eight Phase Programming
      2. 9.1.2 Inner Current Loop Small Signal Models
        1. Small Signal Model
        2. Inner Current Loop Compensation
      3. 9.1.3 Compensating for the Non-Ideal Current Sense Resistor
      4. 9.1.4 Outer Voltage Loop Control
    2. 9.2 Typical Application
      1. 9.2.1 60-A, Dual-Phase, 48-V to 12-V Bidirectional Converter
        1. Design Requirements
        2. Detailed Design Procedure
          1.  Determining the Duty Cycle
          2.  Oscillator Programming
          3.  Power Inductor, RMS and Peak Currents
          4.  Current Sense (RCS)
          5.  Current Setting Limits (ISETA or ISETD)
          6.  Peak Current Limit
          7.  Power MOSFETS
          8.  Bias Supply
          9.  Boot Strap
          10. RAMP Generators
          11. OVP
          12. Dead Time
          13. IOUT Monitors
          14. UVLO Pin Usage
          15. VIN Pin Configuration
          16. Loop Compensation
          17. Soft Start
          18. ISET Pins
        3. Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Development Support
    2. 12.2 Receiving Notification of Documentation Updates
    3. 12.3 Support Resources
    4. 12.4 Trademarks
    5. 12.5 Electrostatic Discharge Caution
    6. 12.6 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Undervoltage Lockout (UVLO) and Master Enable or Disable

The UVLO pin serves as the master enable or disable pin. To use the UVLO pin to program undervoltage lockout control for the HV-port, LV-port, or VCC rail, see Optional UVLO Programming for details.

There are two UVLO voltage thresholds. When the pin voltage is externally pulled below 1.25 V, the LM5170 is in shutdown mode, in which all gate drivers are in the OFF state, all internal logic resets, the VINX pin is disconnected from VIN pin, and the IC draws less than 20 µA through the VIN, VCC and VCCA pins.

When the VCC voltage is above the 8.5 V and the UVLO pin voltage is pulled higher than 1.5 V but lower than 2.5 V, the LM5170 is in the initialization mode in which the nFAULT pin is pulled up to approximately 5 V, but the rest of the LM5170 remain off.

When the UVLO pin is pulled higher than 2.5 V, which is the UVLO release threshold and the master enable threshold, the LM5170 starts the MOSFET failure detection in a period of 2 to 3 ms (see Power MOSFET Failure Detection and Failure Protection (nFAULT, BRKG, BRKS)). If no failure is detected, BRKG pin starts to source a 330-µA current to charge the gates of the breaker MOSFETs.

When the BRKG to BRKS voltage is above 8.5 V, the LM5170 enters standby mode. In standby mode, the VINX pin is internally connected to the VIN pin through an internal cutoff switch (see Figure 20), and the internal 1-MΩ OVPB pullup resistor is connected to the CSB1 pin through another internal cutoff switch (see Figure 36). The oscillator and the RAMP1 and RAMP2 generators start to operate, and the SYNCOUT pin starts to send clock pulses at the oscillator frequency, and the LM5170 is ready to operate. The LO1, LO2, HO1, and HO2 drivers remain off until the EN1, EN2, and DIR inputs command them to operate.

When a MOSFET gate-to-source short-circuit failure is detected, the LM5170 is latched off. The latch can only be reset by pulling the VCC pin below 8 V, or by pulling the UVLO pin below 1.25 V. For details, see Power MOSFET Failure Detection and Failure Protection (nFAULT, BRKG, BRKS).