ZHCSCO8E June   2014  – May 2019 TPS65283 , TPS65283-1

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 典型电路原理图
    1.     效率，Vin = 12V，PSM
  5. 5 修订历史记录
  6. 6 说明 （续）
  7. 7 Pin Configuration and Functions
    1.     Pin Functions
  8. 8 Specifications
    1. 8.1 Absolute Maximum Ratings
    2. 8.2 Handling Ratings
    3. 8.3 Recommended Operating Conditions
    4. 8.4 Thermal Information
    5. 8.5 Electrical Characteristics
    6. 8.6 Typical Characteristics
  9. 9 Detailed Description
    1. 9.1 Overview
    2. 9.2 Functional Block Diagram
    3. 9.3 Feature Description
      1. 9.3.1 Power Switch Detailed Description
        1. 9.3.1.1 Overcurrent Condition
        2. 9.3.1.2 Reverse Current and Voltage Protection
        3. 9.3.1.3 nFAULT Response
        4. 9.3.1.4 UVLO
        5. 9.3.1.5 Enable and Output Discharge
        6. 9.3.1.6 Power Switch Input and Output Capacitance
        7. 9.3.1.7 Programming the Current-Limit Threshold
      2. 9.3.2 Buck DC-DC Converter Detailed Description
        1. 9.3.2.1  Output Voltage
        2. 9.3.2.2  Adjustable Switching Frequency
        3. 9.3.2.3  Synchronization
        4. 9.3.2.4  Error Amplifier
        5. 9.3.2.5  Slope Compensation
        6. 9.3.2.6  Enable and Adjusting UVLO
        7. 9.3.2.7  Internal V7V Regulator
        8. 9.3.2.8  Short Circuit Protection
          1. 9.3.2.8.1 High-Side MOSFET Overcurrent Protection
          2. 9.3.2.8.2 Low-Side MOSFET Overcurrent Protection
        9. 9.3.2.9  Bootstrap Voltage (BST) and Low Dropout Operation
        10. 9.3.2.10 Output Overvoltage Protection (OVP)
        11. 9.3.2.11 Power Good
        12. 9.3.2.12 Power-Up Sequencing
        13. 9.3.2.13 Thermal Performance
    4. 9.4 Device Functional Modes
      1. 9.4.1 Operation With VIN < 4.5 V (Minimum VIN)
      2. 9.4.2 Operation With EN Control
      3. 9.4.3 Operation at Light Loads
  10. 10Application and Implementation
    1. 10.1 Application Information
    2. 10.2 Typical Application
      1. 10.2.1 Design Requirements
      2. 10.2.2 Detailed Design Procedure
        1. 10.2.2.1 Output Voltage Setting
        2. 10.2.2.2 Bootstrap Capacitor Selection
        3. 10.2.2.3 Inductor Selection
        4. 10.2.2.4 Output Capacitor Selection
        5. 10.2.2.5 Input Capacitor Selection
        6. 10.2.2.6 Minimum Output Voltage
        7. 10.2.2.7 Compensation Component Selection
      3. 10.2.3 Application Curves
  11. 11Power Supply Recommendations
  12. 12Layout
    1. 12.1 Layout Guidelines
      1. 12.1.1 PCB Layout Recommendation
      2. 12.1.2 Power Dissipation and Junction Temperature
    2. 12.2 Layout Example
  13. 13器件和文档支持
    1. 13.1 文档支持
      1. 13.1.1 相关链接
    2. 13.2 商标
    3. 13.3 静电放电警告
    4. 13.4 Glossary
  14. 14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

10.2.2.4 Output Capacitor Selection

There are two primary considerations for selecting the value of the output capacitor. The output capacitors are selected to meet load transient and output ripple’s requirements. Equation 10 gives the minimum output capacitance to meet the transient specification. For this example, Lo = 4.7 µH, ΔIout = 2 A – 0.0 A = 2 A, and ΔVout = 250 mV (5% of regulated 5 V) for Buck2. Using these numbers gives a minimum capacitance of 15 µF. This design uses a standard 2 × 22-µF ceramic.

Equation 10. TPS65283 TPS65283-1 Eq14_Co_slvscl3.gif

The selection of COUT is driven by the effective series resistance (ESR). Equation 11 calculates the minimum output capacitance needed to meet the output voltage ripple specification. Where ƒsw is the switching frequency, ΔVout is the maximum allowable output voltage ripple, and ΔiL is the inductor ripple current. In this case, the maximum output voltage ripple is 25 mV (0.5% of regulated 5 V). From Equation 9, the output current ripple is 1.24 A. From Equation 11, the minimum output capacitance meeting the output voltage ripple requirement is
14.5 µF with 3-mΩ ESR resistance.

Equation 11. TPS65283 TPS65283-1 Eq15_Co_slvscl3.gif

After considering both requirements, for this example, four 22-µF 6.3-V X7R ceramic capacitor with 3 mΩ of ESR are used. Equation 12 calculates the maximum ESR an output capacitor can have to meet the output voltage ripple specification. Equation 12 indicates the ESR should be less than 20.2 mΩ. In this case, the ceramic caps’ ESR is much smaller than 20.2 mΩ.

Equation 12. TPS65283 TPS65283-1 Eq16_vorip_slvscl3.gif

Factor in additional capacitance deratings for aging, temperature, and dc bias, which increase this minimum value. This example uses a 22-µF 6.3-V X5R ceramic capacitor with 3 mΩ of ESR. Capacitors generally have limits to the amount of ripple current they can handle without failing or producing excess heat. An output capacitor that can support the inductor ripple current must be specified. Some capacitor data sheets specify the root mean square (RMS) value of the maximum ripple current. Equation 13 can be used to calculate the RMS ripple current the output capacitor needs to support. For this application, Equation 13 yields 385 mA.

Equation 13. TPS65283 TPS65283-1 Eq17_Icorms_slvscl3.gif