ZHCSBB4B July   2013  – June 2017 TPS61197

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用范围
  3. 3 说明
    1.     Device Images
      1.      简化原理图
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Switching Characteristics
    7. 6.7 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 Supply Voltage
      2. 7.3.2 Boost Controller
      3. 7.3.3 Switching Frequency
      4. 7.3.4 Enable and Undervoltage Lockout
      5. 7.3.5 Power-Up Sequencing and Soft Start-up
      6. 7.3.6 Current Regulation
      7. 7.3.7 PWM Dimming
      8. 7.3.8 Indication for Fault Conditions
    4. 7.4 Device Functional Modes
      1. 7.4.1 Protections
        1. 7.4.1.1 Switch Current Limit Protection Using the ISNS Pin
        2. 7.4.1.2 LED Open Protection
        3. 7.4.1.3 Schottky Diode Open Protection
        4. 7.4.1.4 Schottky Diode Short Protection
        5. 7.4.1.5 IFB Overvoltage Protection
        6. 7.4.1.6 Output Overvoltage Protection Using the OVP Pin
        7. 7.4.1.7 IFB Short-to-Ground Protection
        8. 7.4.1.8 Thermal Shutdown
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Simple Boost Converter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Inductor Selection
          2. 8.2.1.2.2 Output Capacitor
          3. 8.2.1.2.3 Schottky Diode
          4. 8.2.1.2.4 Switch MOSFET and Gate Driver Resistor
          5. 8.2.1.2.5 Current Sense and Current Sense Filtering
          6. 8.2.1.2.6 Loop Consideration
        3. 8.2.1.3 Application Curves
      2. 8.2.2 PWM Dimming Controlled by Boost Converter
      3. 8.2.3 High Boost Ratio Application
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11器件和文档支持
    1. 11.1 接收文档更新通知
    2. 11.2 社区资源
    3. 11.3 商标
    4. 11.4 静电放电警告
    5. 11.5 Glossary
  12. 12机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

7.3.5 Power-Up Sequencing and Soft Start-up

The input voltage, UVLO pin voltage, EN input signal, and the input dimming PWM signal control the power up of the TPS61197. After the input voltage is above the required minimal input voltage of 7.5 V, the internal circuit is ready to be powered up. After the UVLO pin voltage is above the threshold of 1.229 V and the EN signal is high, the internal LDO and logic circuit are activated. When the PWM dimming signal is high, the soft start-up begins.

TPS61197 power_up_seq_lvsc25.gifFigure 16. Power-Up Sequencing

The TPS61197 has integrated the soft-start circuitry working with an external capacitor at the REF pin to avoid inrush current during start-up. During the start-up period, the capacitor at the REF pin is charged with a soft-start current source. When the REF pin voltage is higher than the output feedback voltage at the OVP pin, the boost controller starts switching, and the output voltage starts to ramp up. At the same time, the LED current regulation circuit starts to drive the LED string. At the beginning of the soft start, the charge current is 200 µA. Once the voltage of the REF pin exceeds 2 V, the charge current stops. The output voltage continues to ramp up until the IFB voltage is in regulation of 300 mV. The total soft-start time is determined by the external capacitance at the REF pin. The capacitance must be within 470 nF to 4.7 µF for different start-up time.

TPS61197 soft_start_lvsc25.gifFigure 17. Soft-Start Waveforms