SLUSD66D September   2019  – February 2021 TPS92520-Q1

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Buck Converter Switching Operation
      2. 7.3.2  Switching Frequency and Adaptive On-Time Control
      3. 7.3.3  Minimum On-Time, Off-Time, and Inductor Ripple
      4. 7.3.4  LED Current Regulation and Error Amplifier
      5. 7.3.5  Start-up Sequence
      6. 7.3.6  Analog Dimming and Forced Continuous Conduction Mode
      7. 7.3.7  External PWM Dimming and Input Undervoltage Lockout (UVLO)
      8. 7.3.8  Internal PWM Dimming
      9. 7.3.9  Shunt FET Dimming or Matrix Beam Application
      10. 7.3.10 Bias Supply
      11. 7.3.11 Bootstrap Supply
      12. 7.3.12 ADC
        1. 7.3.12.1 Input Voltage Measurement: VINx
        2. 7.3.12.2 LED Voltage Measurement: CSNx
        3. 7.3.12.3 Bias Supply Measurement: V5D
        4. 7.3.12.4 External Limp-Home Input Measurement: LHI
        5. 7.3.12.5 Junction Temperature Measurement: TEMP
      13. 7.3.13 Faults and Diagnostics
      14. 7.3.14 Output Short Circuit Fault
      15. 7.3.15 Output Open Circuit Fault
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power On Reset (POR)
      2. 7.4.2 Detect SPI Communication
      3. 7.4.3 Standalone Mode
      4. 7.4.4 Load Mode
      5. 7.4.5 Run Mode
      6. 7.4.6 Sleep Mode
      7. 7.4.7 Limp-Home Mode
    5. 7.5 Programming
      1. 7.5.1 Serial Interface
      2. 7.5.2 Command Frame
      3. 7.5.3 Response Frame
        1. 7.5.3.1 Read Response Frame Format
        2. 7.5.3.2 Write Response Frame Format
        3. 7.5.3.3 Write Error/POR Frame Format
      4. 7.5.4 SPI Error
      5. 7.5.5 SPI for Multiple Slave Devices in Parallel Configuration
      6. 7.5.6 SPI for Multiple Slave Devices in Daisy Chain Configuration
    6. 7.6 Register Maps
      1. 7.6.1 Configuration Registers
        1. 7.6.1.1 SYSCFG1 Register (address = 0x00) [reset = 0x10]
        2. 7.6.1.2 SYSCFG2 Register (address = 0x01) [reset = 0x00]
        3. 7.6.1.3 CMWTAP Register (address = 0x02) [reset = 0x08]
      2. 7.6.2 STATUS Registers
        1. 7.6.2.1 STATUS1 Register (address = 0x03)
        2. 7.6.2.2 STATUS2 Register (address = 0x04)
        3. 7.6.2.3 STATUS3 Register (address = 0x05)
      3. 7.6.3 Device Control Registers
        1. 7.6.3.1  Thermal Warning Limit (address = 0x06) [reset = 0x8A]
        2. 7.6.3.2  SLEEP Command (address = 0x07) [reset = 0x00]
        3. 7.6.3.3  CH1IADJL Control Register (address = 0x08) [reset = 0x00]
        4. 7.6.3.4  CH1IADJH Control Register (address = 0x09) [reset = 0x00]
        5. 7.6.3.5  CH2IADJL Control Register (address = 0x0A) [reset = 0x00]
        6. 7.6.3.6  CH2IADJH Control Register (address = 0x0B) [reset = 0x00]
        7. 7.6.3.7  PWMDIV Register (address = 0x0C) [reset = 0x04]
        8. 7.6.3.8  CH1PWML Register (address = 0x0D) [reset = 0x00]
        9. 7.6.3.9  CH1PWMH Register (address = 0x0E) [reset = 0x00]
        10. 7.6.3.10 CH2PWML Register (address = 0x0F) [reset = 0x00]
        11. 7.6.3.11 CH2PWMH Register (address = 0x10) [reset = 0x00]
        12. 7.6.3.12 CH1TON Register (address = 0x11) [reset = 0x07]
        13. 7.6.3.13 CH2TON Register (address = 0x12) [reset = 0x07]
      4. 7.6.4 ADC Measurements
        1. 7.6.4.1  CH1VIN Measurement (address = 0x13)
        2. 7.6.4.2  CH1VLED Measurement (address = 0x14)
        3. 7.6.4.3  CH1VLEDON Measurement (address = 0x15)
        4. 7.6.4.4  CH1VLEDOFF Measurement (address = 0x16)
        5. 7.6.4.5  CH2VIN Measurement (address = 0x17)
        6. 7.6.4.6  CH2VLED Measurement (address = 0x18)
        7. 7.6.4.7  CH2VLEDON Measurement (address = 0x19)
        8. 7.6.4.8  CH2VLEDOFF Measurement (address = 0x1A)
        9. 7.6.4.9  TEMPL Measurement (address = 0x1B)
        10. 7.6.4.10 TEMPH Measurement (address = 0x1C)
        11. 7.6.4.11 V5D Measurement (address = 0x1D)
      5. 7.6.5 Limp-Home Configuration and Command Registers
        1. 7.6.5.1  LHCFG1 Register (address = 0x1E) [reset =0x00]
        2. 7.6.5.2  LHCFG2 Register (address = 0x1F) [reset =0x00h]
        3. 7.6.5.3  LHIL Measurement (address = 0x20)
        4. 7.6.5.4  LHIH Measurement (address = 0x21)
        5. 7.6.5.5  LHIFILTL Register (address = 0x22)
        6. 7.6.5.6  LHIFILTH Register (address = 0x23)
        7. 7.6.5.7  LH1IADJL Register (address = 0x24) [reset = 0x00]
        8. 7.6.5.8  LH1IADJH Register (address = 0x25) [reset = 0x00]
        9. 7.6.5.9  LH2IADJL Register (address = 0x26) [reset = 0x00]
        10. 7.6.5.10 LH2IADJH Register (address = 0x27) [reset = 0x00]
        11. 7.6.5.11 LH1PWML Register (address = 0x28) [reset = 0x00]
        12. 7.6.5.12 LH1PWMH Register (address = 0x29) [reset = 0x00]
        13. 7.6.5.13 LH2PWML Register (address = 0x2A) [reset = 0x00]
        14. 7.6.5.14 LH2PWMH Register (address = 0x2B) [reset = 0x00]
        15. 7.6.5.15 LH1TON Register (address = 0x2C) [reset = 0x07]
        16. 7.6.5.16 LH2TON Register (address = 0x2D) [reset = 0x07]
      6. 7.6.6 RESET Register (address = 0x2E) (Write-Only)
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1  Duty Cycle Consideration
      2. 8.1.2  Switching Frequency Selection
      3. 8.1.3  LED Current Set Point
      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 Undervoltage Protection
      10. 8.1.10 CSN Protection Diode
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
        1. 8.2.1.1 Detailed Design Procedure
          1. 8.2.1.1.1 Calculating Duty Cycle
          2. 8.2.1.1.2 Calculating Minimum On-Time and Off-Time
          3. 8.2.1.1.3 Minimum Switching Frequency
          4. 8.2.1.1.4 LED Current Set Point
          5. 8.2.1.1.5 Inductor Selection
          6. 8.2.1.1.6 Output Capacitor Selection
          7. 8.2.1.1.7 Bootstrap Capacitor Selection
          8. 8.2.1.1.8 Compensation Capacitor Selection
          9. 8.2.1.1.9 External Channel Enable and PWM dimming
      2. 8.2.2 Application Curves
    3. 8.3 Initialization Setup
      1. 8.3.1 Initialize Device without Watchdog timer
      2. 8.3.2 Initialize Device with Watchdog Timer
      3. 8.3.3 Limp-Home Mode
  9. 9 Power Supply Recommendations
  10. 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
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.2 Switching Frequency and Adaptive On-Time Control

The TPS92520-Q1 uses an adaptive on-time control scheme and does not have a dedicated on-board oscillator. The one-shot timer incorporates a 6-bit current steering DAC and is programmed by the CHxTON registers. The on-time is calculated internally using Equation 1 and is inversely proportional to the measured input voltage, VIN, and proportional to the measured CSP voltage, VCSP.

Equation 1. GUID-8BA62093-E1A5-478F-A84F-81094F98E699-low.gif

Given the duty ratio of the buck converter is VCSP / VIN, the switching period, TSW, remains nearly constant over all operating points. Use Equation 2 to calculate the switching period.

Equation 2. GUID-2FAA8E03-3975-40E9-8255-478AA56A1980-low.gif

Use Equation 3 to calculate the switching frequency.

Equation 3. GUID-DF2D6C07-7849-4BD7-A967-46B3B52A69A7-low.gif

TI recommends a switching frequency setting between 110 kHz and 2.2 MHz, corresponding to a decimal value of the CHxTON register ranging from 1 to 43.