SLUSCV5 May   2022 TPS92643-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Internal Regulator
      2. 7.3.2  Buck Converter Switching Operation
      3. 7.3.3  Bootstrap Supply
      4. 7.3.4  Switching Frequency and Adaptive On-Time Control
      5. 7.3.5  Minimum On-Time, Off-Time, and Inductor Ripple
      6. 7.3.6  LED Current Regulation and Error Amplifier
      7. 7.3.7  Start-Up Sequence
      8. 7.3.8  Analog Dimming and Forced Continuous Conduction Mode
      9. 7.3.9  External PWM Dimming and Input Undervoltage Lockout (UVLO)
      10. 7.3.10 Analog Pulse Width Modulator Circuit
      11. 7.3.11 Output Short and Open-Circuit Faults
      12. 7.3.12 Overcurrent Protection
      13. 7.3.13 Thermal Shutdown
      14. 7.3.14 Fault Indicator and Diagnostics Summary
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Duty Cycle Considerations
      2. 8.1.2  Switching Frequency Selection
      3. 8.1.3  LED Current Programming
      4. 8.1.4  Inductor Selection
      5. 8.1.5  Output Capacitor Selection
      6. 8.1.6  Input Capacitor Selection
      7. 8.1.7  Bootstrap Capacitor Selection
      8. 8.1.8  Compensation Capacitor Selection
      9. 8.1.9  Input Dropout and Undervoltage Protection
      10. 8.1.10 APWM Input and Thermal Protection
      11. 8.1.11 Protection Diodes
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Calculating Duty Cycle
        2. 8.2.2.2 Calculating Minimum On-Time and Off-Time
        3. 8.2.2.3 Minimum Switching Frequency
        4. 8.2.2.4 LED Current Set Point
        5. 8.2.2.5 Inductor Selection
        6. 8.2.2.6 Output Capacitor Selection
        7. 8.2.2.7 Bootstrap Capacitor Selection
        8. 8.2.2.8 Compensation Capacitor Selection
        9. 8.2.2.9 VIN Dropout Protection and PWM Dimming
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Compact Layout for EMI Reduction
          1. 8.4.1.1.1 Ground Plane
      2. 8.4.2 Layout Example
  10. 9 Power Supply Recommendations
  11. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Compact Layout for EMI Reduction
        1. 10.1.1.1 Ground Plane
    2. 10.2 Layout Example
  12. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.14 Fault Indicator and Diagnostics Summary

Table 7-1 summarizes the device behavior under fault conditions.

Table 7-1 Fault Description
FAULT DETECTION DESCRIPTION
Thermal protection TJ > 175°C The thermal protection is activated in the event the maximum MOSFET temperature exceeds the typical value of 175°C. This feature is designed to prevent overheating and damage to the internal switching MOSFETs.
VCC undervoltage lockout VCC(RISE) < 4.4 V The device enters the Undervoltage Lockout (UVLO). The switching operation is disabled, the COMP capacitor is discharged.
VCC(FALL) < 4.2 V
VIN dropout protection VUDIM < 2.34 V The device disables error amplifier and disconnects the compensation network for the corresponding channel. Error amplifier is enabled and compensation network is internally connected when the input voltage rises above the dropout rising threshold, VIN(DO,RISE).
VIN undervoltage lockout VUDIM < 1.12 V The device disables switching operation for the corresponding channel. Switching is enabled when the input voltage rises above the turn-on threshold, VIN(UVLO,RISE).
BST undervoltage lockout VBST(RISE) < 3.2 V The device turns off the high-side MOSFET and turns on the low-side MOSFET for the corresponding channel. Normal switching operation is resumed after the bootstrap voltage exceeds 3.2 V.
VBST(FALL) < 2.93 V
COMP overvoltage VCOMP > 3.2 V The FLT flag is set low to indicate that the COMP voltage exceeded the normal operating range. This condition indicates output open-circuit fault.
Short output VCSN < 1.5 V The FLT flag is set low to indicate an output short-circuit condition based on sensed CSN voltage.
High-side switch current limit IHS > 4.8 A The device turns off the high-side MOSFET, turns on low-side MOSFET and discharges the COMP capacitor. The device attempts to restart after a delay of 5.5 ms.
Low-side switch current limit ILS > 3.2 A The device turns off both high-side and low-side MOSFETs and discharges the COMP capacitor. The device attempts to restart after a delay of 5.5 ms.

Output open and short circuit faults force the FLT pin low when biased through an external resistor and connected to a 5-V supply. The FLT output can be used in conjunction with a microcontroller or system basis chip (SBC) as an interrupt and aid in fault diagnostics.