SNVS859C July   2012  – September 2016 LM25101


  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Device Options
  6. Pin Configuration and 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 Switching Characteristics
    7. 7.7 Typical Characteristics
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Start-Up and UVLO
      2. 8.3.2 Level Shift
      3. 8.3.3 Output Stages
    4. 8.4 Device Functional Modes
  9. Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. Selecting External Gate Driver Resistor
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Community Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

10 Power Supply Recommendations

The total IC power dissipation is the sum of the gate driver losses and the bootstrap diode losses. The gate driver losses are related to the switching frequency (f), output load capacitance on LO and HO (CL), and supply voltage (VDD), which can be roughly calculated using Equation 5.

Equation 5. PDGATES = 2 × f × CL × VDD2

There are some additional losses in the gate drivers due to the internal CMOS stages used to buffer the LO and HO outputs. Figure 24 shows the measured gate driver power dissipation versus frequency and load capacitance. At higher frequencies and load capacitance values, the power dissipation is dominated by the power losses driving the output loads and agrees well with Equation 5. Figure 24 can be used to approximate the power losses due to the gate drivers.

The bootstrap diode power loss is the sum of the forward bias power loss that occurs while charging the bootstrap capacitor and the reverse bias power loss that occurs during reverse recovery. Since each of these events happens once per cycle, the diode power loss is proportional to frequency. Larger capacitive loads require more energy to recharge the bootstrap capacitor resulting in more losses. Higher input voltages (VIN) to the half bridge result in higher reverse recovery losses. Figure 25 was generated based on calculations and lab measurements of the diode recovery time and current under several operating conditions and can be used to approximate the diode power dissipation.

The total IC power dissipation can be estimated from these plots by summing the gate drive losses with the bootstrap diode losses for the intended application.

LM25101 30192905.gif
VDD = 12 V Neglecting Diode Losses
Figure 24. Gate Driver Power Dissipation (LO + HO)
LM25101 30192906.gif
VIN = 50 V
Figure 25. Diode Power Dissipation