ZHCSJN7J October   2002  – May 2019 TPS795

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      TPS79530 波纹抑制与频率
      2.      TPS79530 与频率
  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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 Shutdown
      2. 7.3.2 Start-Up
      3. 7.3.3 Undervoltage Lockout (UVLO)
      4. 7.3.4 Regulator Protection
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 Dropout Operation
      3. 7.4.3 Disabled
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input and Output Capacitor Requirements
        2. 8.2.2.2 Output Noise
        3. 8.2.2.3 Dropout Voltage
        4. 8.2.2.4 Programming the TPS79501 Adjustable LDO Regulator
      3. 8.2.3 Application Curves
    3. 8.3 What to Do and What Not to Do
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Board Layout Recommendation to Improve PSRR and Noise Performance
      2. 10.1.2 Regulator Mounting
      3. 10.1.3 Thermal Considerations
      4. 10.1.4 Estimating Junction Temperature
    2. 10.2 Layout Examples
  11. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 开发支持
        1. 11.1.1.1 评估模块
        2. 11.1.1.2 Spice 模型
      2. 11.1.2 器件命名规则
    2. 11.2 文档支持
      1. 11.2.1 相关文档
    3. 11.3 接收文档更新通知
    4. 11.4 社区资源
    5. 11.5 商标
    6. 11.6 静电放电警告
    7. 11.7 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

8.2.2.4 Programming the TPS79501 Adjustable LDO Regulator

The output voltage of the TPS79501 adjustable regulator is programmed using an external resistor divider as shown in Figure 26.

TPS795 ai_adj_ldo_lvs350.gifFigure 26. Typical Application, Adjustable Output

The output voltage is calculated using Equation 1.

Equation 1. TPS795 q_vout_lvs350.gif

where

  • VREF = 1.2246 V typical (the internal reference voltage)

Resistors R1 and R2 should be chosen for approximately 40-µA divider current. Lower value resistors can be used for improved noise performance, but the device wastes more power. Higher values should be avoided, as leakage current at FB increases the output voltage error.

The recommended design procedure is to choose R2 = 30.1 kΩ to set the divider current at 40 µA, C1 = 15 pF for stability, and then calculate R1 using Equation 2.

Equation 2. TPS795 q_r1_lvs350.gif

To improve the stability of the adjustable version, TI suggests placing a small compensation capacitor between OUT and FB.

The approximate value of this capacitor can be calculated using Equation 3.

Equation 3. TPS795 q_c1_lvs350.gif

The suggested value of this capacitor for several resistor ratios is shown in the table within Figure 26. If this capacitor is not used (such as in a unity-gain configuration), then the minimum recommended output capacitor is 2.2 µF instead of 1 µF.