SLVSHB5A October   2024  – November 2024 TPS61287

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 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Enable and Start-up
      2. 6.3.2 Undervoltage Lockout (UVLO)
      3. 6.3.3 Programmable EN/UVLO
      4. 6.3.4 Switching Valley Current Limit
      5. 6.3.5 External Clock Synchronization
      6. 6.3.6 Stackable Multi-phase Operation
      7. 6.3.7 Device Functional Modes
        1. 6.3.7.1 Forced PWM Mode
        2. 6.3.7.2 Auto PFM Mode
      8. 6.3.8 Overvoltage Protection
      9. 6.3.9 Thermal Shutdown
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Setting Output Voltage
        2. 7.2.2.2 Inductor Selection
        3. 7.2.2.3 Bootstrap And VCC Capacitors Selection
        4. 7.2.2.4 MOSFET Selection
        5. 7.2.2.5 Input Capacitor Selection
        6. 7.2.2.6 Output Capacitor Selection
        7. 7.2.2.7 Loop Stability
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
        1. 7.4.2.1 Thermal Considerations
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 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

7.2.2.4 MOSFET Selection

The external power MOSFET must be selected with VDS rating that can withstand the maximum output voltage plus transient spikes (ringing). 40V rated MOSFET is selected in this application.

Once the voltage rating is determined, select the MOSFETs by making tradeoffs between MOSFET RDS(ON) and total gate charge (Qg) to balance conduction and switching losses.

Be aware of the deadtime limitation, verify that the low-side and high-side MOSFET are not turned on simultaneously. A leadless package is preferred for this high switching-frequency design to minimumize the driving parasitic inductance. Be careful when adding series gate resistors, as this can decrease the effective deadtime.

The MOSFET gate driver current of the device is supplied from VCC. Before start-up, the VCC voltage is powered from VIN from an internal LDO. Verify that the gate threshold voltage(Vth) of MOSFET is lower than minimum VIN voltage for the target design to guarntee a fully turn on of the MOSFET.

The maximum gate charge power is limited by the 15mA VCC sourcing current limit. Driving loss must be considered to meet the sourcing current limit of VCC.