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

7.3.2 Boost Controller

The TPS61197 regulates the output voltage with peak current mode PWM control. The control circuitry turns on an external switch FET at the beginning of each switching cycle. The input voltage is applied across the inductor and stores the energy as the inductor current ramps up. During this portion of the switching cycle, the load current is provided by the output capacitor. When the inductor current rises to the threshold set by the error amplifier (EA) output, the switch FET is turned off and the external Schottky diode is forward biased. The inductor transfers stored energy to replenish the output capacitor and supply the load current. This operation repeats each switching cycle. The switching frequency is programmed by an external resistor.

A ramp signal from the oscillator is added to the current ramp to provide slope compensation, shown in the Functional Block Diagram. The duty cycle of the converter is then determined by the PWM logic block which compares the EA output and the slope compensated current ramp. The feedback loop regulates the OVP pin to a reference voltage generated by the current regulation control circuit which senses the LED current at the IFB pin. The output of the EA is connected to the COMP pin. An external RC compensation network must be connected to the COMP pin to optimize the feedback loop for stability and transient response.

The TPS61197 consistently adjusts the boost output voltage to account for any changes in LED forward voltages. In the event that the boost controller is not able to regulate the output voltage due to the minimum pulse width (ton(min), in the Electrical Characteristics table), the TPS61197 enters pulse skip mode. In this mode, the device keeps the power switch off for several switching cycles to prevent the output voltage from rising above the regulated voltage. This operation typically occurs in light load condition or when the input voltage is higher than the output voltage.