SLVSB90C January   2012  – November 2023 TPS40170-Q1

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  LDO Linear Regulators and Enable
      2. 6.3.2  Input Undervoltage Lockout (UVLO)
      3. 6.3.3  Equations for Programming the Input UVLO
      4. 6.3.4  Overcurrent Protection and Short-Circuit Protection (OCP and SCP)
      5. 6.3.5  Oscillator and Voltage Feed-Forward
        1. 6.3.5.1 Calculating the Timing Resistance (RRT)
      6. 6.3.6  Feed-Forward Oscillator Timing Diagram
      7. 6.3.7  Soft-Start and Fault-Logic
        1. 6.3.7.1 Soft-Start During Overcurrent Fault
        2. 6.3.7.2 Equations for Soft-Start and Restart Time
      8. 6.3.8  Overtemperature Fault
      9. 6.3.9  Tracking
      10. 6.3.10 Adaptive Drivers
      11. 6.3.11 Start-Up Into Pre-Biased Output
      12. 6.3.12 31
      13. 6.3.13 Power Good (PGOOD)
      14. 6.3.14 PGND and AGND
      15. 6.3.15 Bootstrap Capacitor
      16. 6.3.16 Bypass and Filtering
    4. 6.4 Device Functional Modes
      1. 6.4.1 Frequency Synchronization
  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  Select A Switching Frequency
        2. 7.2.2.2  Inductor Selection (L1)
        3. 7.2.2.3  Output Capacitor Selection (C9)
        4. 7.2.2.4  Peak Current Rating of Inductor
        5. 7.2.2.5  Input Capacitor Selection (C1, C6)
        6. 7.2.2.6  MOSFET Switch Selection (Q1, Q2)
        7. 7.2.2.7  Timing Resistor (R7)
        8. 7.2.2.8  UVLO Programming Resistors (R2, R6)
        9. 7.2.2.9  Bootstrap Capacitor (C7)
        10. 7.2.2.10 VIN Bypass Capacitor (C18)
        11. 7.2.2.11 VBP Bypass Capacitor (C19)
        12. 7.2.2.12 SS Timing Capacitor (C15)
        13. 7.2.2.13 ILIM Resistor (R19, C17)
        14. 7.2.2.14 SCP Multiplier Selection (R5)
        15. 7.2.2.15 Feedback Divider (R10, R11)
        16. 7.2.2.16 Compensation: (R4, R13, C13, C14, C21)
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
      1. 7.3.1 Bootstrap Resistor
      2. 7.3.2 SW-Node Snubber Capacitor
      3. 7.3.3 Input Resistor
      4. 7.3.4 LDRV Gate Capacitor
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.8 Overtemperature Fault

Figure 6-8 shows the over temperature protection scheme. If the junction temperature of the device reaches the thermal shutdown limit of tSD(set) (165°C, typical) and SS charging is completed, an overtemperature FAULT is declared. The soft-start capacitor begins to be discharged. During soft-start discharging period, the PWM switching is terminated; therefore, both HDRV and LDRV are driven low, turning off both MOSFETs.

The soft-start capacitor begins to charge and an overtemperature fault is reset whenever the soft-start capacitor is discharged below VSS(flt,low) (300 mV, typical). During each restart cycle, PWM switching is turned on. When SS is fully charged, PWM switching is terminated. These restarts repeat until the temperature of the device has fallen below the thermal reset level, tSD(reset) (135°C typical). PWM switching continues and the system returns to normal regulation.

GUID-3E5B721B-34FC-4B0A-BACD-96F325516782-low.gifFigure 6-8 Overtemperature Fault Restart Timing

The soft-start timing during an overtemperature fault is the same as the soft-start timing during an overcurrent fault. See the Equations for Soft-Start and Restart Time section.