SLUSEE5E January   2022  – April 2026 TPS4811-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Recommended Operating Conditions
    3. 6.3 ESD Ratings
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Charge Pump and Gate Driver output (VS, PU, PD, BST, SRC)
      2. 8.3.2 Capacitive Load Driving
        1. 8.3.2.1 FET Gate Slew Rate Control
        2. 8.3.2.2 Using Precharge FET - (with TPS48111Q1 Only)
      3. 8.3.3 Overcurrent and Short-Circuit Protection
        1. 8.3.3.1 Overcurrent Protection With Auto-Retry
        2. 8.3.3.2 Overcurrent Protection With Latch-Off
        3. 8.3.3.3 Short-Circuit Protection
      4. 8.3.4 Analog Current Monitor Output (IMON)
      5. 8.3.5 Overvoltage (OV) and Undervoltage Protection (UVLO)
      6. 8.3.6 Remote Temperature sensing and Protection (DIODE)
      7. 8.3.7 Output Reverse Polarity Protection
      8. 8.3.8 TPS4811x-Q1 as a Simple Gate Driver
    4. 8.4 Device Functional Mode (Shutdown Mode)
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application: Driving HVAC PTC Heater Load on KL40 Line in Power Distribution Unit
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Selection of Current Sense Resistor, RSNS
        2. 9.2.2.2 Selection of Scaling Resistor, RSET
        3. 9.2.2.3 Programming the Overcurrent Protection Threshold - RIWRN Selection
        4. 9.2.2.4 Programming the Short-Circuit Protection Threshold - RISCP Selection
        5. 9.2.2.5 Programming the Fault Timer Period - CTMR Selection
        6. 9.2.2.6 Selection of MOSFET, Q1
        7. 9.2.2.7 Selection of Bootstrap Capacitor, CBST
        8. 9.2.2.8 Setting the Undervoltage Lockout and Overvoltage Set Point
        9. 9.2.2.9 Choosing the Current Monitoring Resistor, RIMON
      3. 9.2.3 Application Curves
    3. 9.3 Typical Application: Driving B2B FETs With Pre-Charging the Output Capacitance
      1. 9.3.1 Design Requirements
      2. 9.3.2 External Component Selection
        1. 9.3.2.1 Selection of Pre-Charge Resistor
      3. 9.3.3 Application Curves
    4. 9.4 Typical Application: Designing for EMI
      1. 9.4.1 Common EMI Components
      2. 9.4.2 Programming the Overcurrent Protection Threshold with Added DC Resistance - RIWRN
      3. 9.4.3 Choosing the Current Monitoring Resistor with Added DC Resistance - RIMON
      4. 9.4.4 Programming the Short Circuit Protection Threshold with Added DC Resistance - RISCP
    5. 9.5 Power Supply and EMI Recommendations
    6. 9.6 Layout
      1. 9.6.1 Layout Guidelines
      2. 9.6.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

9.2.2.7 Selection of Bootstrap Capacitor, CBST

The internal charge pump charges the external bootstrap capacitor (connected between BST and SRC pins) with approximately 100μA. In case of switching applications, the BST must be powered externally from VAUX supply (ranging between 8.1V to 15V) through a low-leakage silicon diode such as CMHD3595 or BAT46WH,115 to avoid collapsing the BST-SRC supply. This need is determined by the value of the switching frequency and MOSFET gate charge.

The maximum possible frequency without external supply is given by Equation 19.

Equation 19. F S W , m a x = I B S T 2 × Q g t o t a l = 581 H z

As the present application is switched at 100Hz, external supply is not required. Use the following equation to calculate the minimum required value of the bootstrap capacitor for driving two parallel BUK7S0R5-40HJ MOSFETs.

Equation 20. C B S T = Q g t o t a l 1 V = 380 n F

Select the closest available standard value: 470nF, 10%.