SNVSBU4E June   2022  – August 2024 LM5177

PRODUCTION DATA  

  1.   1
  2. Features
  3. Applications
  4. Description
  5. Pin Configuration and Functions
  6. Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 Handling Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. Parameter Measurement Information
    1. 6.1 Gate Driver Rise Time and Fall Time
    2. 6.2 Gate Driver Dead (Transition) Time
  8. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Power-On Reset (POR System)
      2. 7.3.2  Buck-Boost Control Scheme
        1. 7.3.2.1 Boost Mode
        2. 7.3.2.2 Buck Mode
        3. 7.3.2.3 Buck-Boost Mode
      3. 7.3.3  Power Save Mode
      4. 7.3.4  Supply Voltage Selection – VMAX Switch
      5. 7.3.5  Enable and Undervoltage Lockout
      6. 7.3.6  Oscillator Frequency Selection
      7. 7.3.7  Frequency Synchronization
      8. 7.3.8  Voltage Regulation Loop
      9. 7.3.9  Output Voltage Tracking
      10. 7.3.10 Slope Compensation
      11. 7.3.11 Configurable Soft Start
      12. 7.3.12 Peak Current Sensor
      13. 7.3.13 Current Monitoring and Current Limit Control Loop
      14. 7.3.14 Short Circuit - Hiccup Protection
      15. 7.3.15 nFLT Pin and Protections
      16. 7.3.16 Device Configuration Pin
      17. 7.3.17 Dual Random Spread Spectrum – DRSS
      18. 7.3.18 Gate Driver
    4. 7.4 Device Functional Modes
  9. 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  Custom Design with WEBENCH Tools
        2. 8.2.2.2  Frequency
        3. 8.2.2.3  Feedback Divider
        4. 8.2.2.4  Inductor and Current Sense Resistor Selection
        5. 8.2.2.5  Slope Compensation
        6. 8.2.2.6  Output Capacitor
        7. 8.2.2.7  Input Capacitor
        8. 8.2.2.8  UVLO Divider
        9. 8.2.2.9  Soft-Start Capacitor
        10. 8.2.2.10 MOSFETs QH1 and QL1
        11. 8.2.2.11 MOSFETs QH2 and QL2
        12. 8.2.2.12 Frequency Compensation
        13. 8.2.2.13 External Component Selection
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1 Bi-Directional Power Backup
      2. 8.3.2 Parallel (Multiphase) Operation
  10. Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Power Stage Layout
      2. 10.1.2 Gate Driver Layout
      3. 10.1.3 Controller Layout
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
        1. 11.1.2.1 Custom Design with WEBENCH Tools
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  13. 12Revision History
  14. 13Mechanical, Packaging, and Orderable Information

Package Options

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

Overview

The LM5177 is a four switch buck-boost controller. The device provides a regulated output voltage if the input voltage is higher, equal, or lower than the adjusted output voltage.

In power save mode, the LM5177 supports superb efficiency over the full rage of the output current. The operation modes are on-the-fly pin-selectable during operation. The proprietary buck-boost modulation scheme also runs at a fixed switching frequency, which can be set through the RT/SYNC pin. The switching frequency remains constant during buck, boost, and buck-boost operation. The device maintains small mode transition ripple over all operating modes. Through the activation of the dual random spread spectrum operation, EMI mitigation is achievable at any time of the design process.

The integrated and optional average current monitor can help monitor or limit input and output current of the LM5177. This feature also supports charging backup power elements, like batteries with constant current (CC) and constant voltage (CV).

The output voltage of the LM5177 can be dynamically adjusted during operation (dynamic voltage scaling and envelope tracking). The adjustment is either possible by changing the analog reference voltage of the SS/ATRK pin or it can be done directly with a PWM input signal on the DTRK pin.

The internal wide input LDOs ensure a robust supply of the device functionality under different input and output voltage conditions. Due to the high drive capability and the automatic and headroom depended voltages selection, the power losses are kept at a minimum at high switching frequency operation. The separate bias pin can be connected to the input, output, or an external supply to further reduce power losses in the device. At all times, the internal supply voltage is monitored to avoid undefined failure handling.

The LM5177 integrates a full bridge N-channel MOSFET driver. The gate driver circuit has a high driving capability to ensure high efficiency targets over the wide range of the supported application. The gate driver features an integrated high voltage low dropout bootstrap diode. The internal bootstrap circuit has a protection against an overvoltage that can be injected by negative spikes and an undervoltage lockout protection to avoid a linear operation of the external power FET. The bootstrap circuit ensures 100% duty cycle operation in pure boost or buck mode.

The resistor-to-digital (R2D) interface offers the user a simple and robust selection of all the device functionality where the analog settings of the soft start minimize the inrush current. Additionally, the control loop and slope compensation ensure a best-in-class output performance for the wide range of supported application cases.

The devices built-in protection features ensure a safe operation under different fault conditions. There is a VIN undervoltage lockout protection to avoid brownout situations. Because the input UVLO threshold and hysteresis can be configured through an external feedback divider, the brownout is avoided under the different designs. The device has an output overvoltage protection and an input overvoltage protection for negative current operation. The selectable hiccup overcurrent protection avoids excessive short circuit currents by using the internal cycle-by-cycle peak current protection. Due to the integrated thermal shutdown, the device is protected against thermal damage caused by an overload condition of the internal VCC regulators. All output-related fault events are monitored and indicated at the open-drain nFLT pin of the device.