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

8.2.1.2.2 Output Capacitor

The output capacitor is mainly selected to meet the requirements for output ripple and loop stability of the whole system. This ripple voltage is related to the capacitance of the capacitor and its equivalent series resistance (ESR). Assuming a capacitor with zero ESR, the minimum capacitance needed for a given ripple can be calculated by:

Equation 9. TPS61197 EQ10_lvsbg1.gif

where

  • VRIPPLE is the peak-to-peak output voltage ripple
  • DMAX is the maximum duty cycle of the boost converter in the application

DMAX is approximately equal to (VOUT(MAX) – VIN(MIN) / VOUT(MAX)) in applications. Care must be taken when evaluating a capacitor’s derating under DC voltage. The DC bias voltage can also significantly reduce capacitance. Ceramic capacitors can loss as much as 50% of its capacitance at its rated voltage. Therefore, leave the margin on the voltage rating to ensure adequate capacitance.

The ESR impact on the output ripple must be considered as well if tantalum or aluminum electrolytic capacitors are used. Assuming there is enough capacitance such that the ripple due to the capacitance can be ignored, the ESR needed to limit the VRIPPLE is:

Equation 10. TPS61197 eq10_vripesr_lvsc25.gif

Ripple current flowing through a capacitor’s ESR causes power dissipation in the capacitor. This power dissipation causes temperature increase internally to the capacitor. Excessive temperature can seriously shorten the expected life of a capacitor. Capacitors have ripple current ratings that are dependent on ambient temperature and must not be exceeded. Therefore, high ripple current type electrolytic capacitor with small ESR is used in the typical application as shown in Figure 18.

In the typical application, the output requires a capacitor in the range of 1 µF to 100 µF. The output capacitor affects the small signal control loop stability of the boost converter. If the output capacitor is below the range, the boost regulator may potentially become unstable.