ZHCSEU9C March   2016  – June 2018 LMZ34202

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      简化应用
      2.      效率与输出电流间的关系
  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
    8. 6.8 Typical Characteristics (Thermal Derating)
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Adjusting the Output Voltage
      2. 7.3.2  Switching Frequency (RT)
      3. 7.3.3  Recommended Operating Range
      4. 7.3.4  Synchronization (CLK)
      5. 7.3.5  Output Capacitor Selection
      6. 7.3.6  VERSA-COMP Pin Configurations
      7. 7.3.7  Input Capacitor Selection
      8. 7.3.8  Output On/Off Inhibit (INH/UVLO)
      9. 7.3.9  Under Voltage Lockout (UVLO)
      10. 7.3.10 Remote Sense
      11. 7.3.11 VBSEL
      12. 7.3.12 Soft-Start (SS/TR)
      13. 7.3.13 Power Good (PWRGD) and Pull-up (PWRGD_PU)
      14. 7.3.14 Overcurrent Protection
      15. 7.3.15 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Active Mode
      2. 7.4.2 Light Load Operation
      3. 7.4.3 Shutdown Mode
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Minimum External Component Application
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2 Output Voltage Set-Point
          3. 8.2.1.2.3 RT and RTSEL
          4. 8.2.1.2.4 VERSA-COMP
          5. 8.2.1.2.5 VBSEL
          6. 8.2.1.2.6 Input Capacitors
          7. 8.2.1.2.7 Output Capacitors
        3. 8.2.1.3 Application Curves
      2. 8.2.2 INH Control Application
        1. 8.2.2.1 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Switching Frequency
        2. 8.2.3.2 Power Good
        3. 8.2.3.3 Inhibit Control
        4. 8.2.3.4 VERSA-COMP
        5. 8.2.3.5 VBSEL
        6. 8.2.3.6 Soft-Start Capacitors
        7. 8.2.3.7 Input Capacitors
        8. 8.2.3.8 Output Capacitors
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 EMI
  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 使用 WEBENCH® 工具创建定制设计
      2. 11.1.2 第三方产品免责声明
    2. 11.2 接收文档更新通知
    3. 11.3 社区资源
    4. 11.4 商标
    5. 11.5 静电放电警告
    6. 11.6 术语表
  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

7.3.9 Under Voltage Lockout (UVLO)

The LMZ34202 device has an internal UVLO circuit which prevents the device from operating until the PVIN voltage exceeds the UVLO threshold, (3.2 V (typ)). The device will begin switching and the output voltage will begin to rise once PVIN exceeds the threshold, however PVIN must be greater than (VOUT/0.75) in order to for VOUT to regulate at the set-point voltage.

Applications may require a higher UVLO threshold to prevent early turn-on, for sequencing requirements, or to prevent input current draw at lower input voltages. An external resistor divider can be added to the INH/UVLO pin to adjust the UVLO threshold higher. The external resistor divider can be configured as shown in Figure 24. Table 10 lists standard values for RUVLO1 and RUVLO2 to adjust the UVLO voltage higher.

LMZ34202 LMZ36002UVLOSetting.gifFigure 24. Adjustable PVIN UVLO

Table 10. Resistor Values for Adjusting PVIN UVLO

PVIN UVLO (V) 4.5 10 15 20 25 30
RUVLO1 (kΩ) 100 100 100 100 100 100
RUVLO2 (kΩ) 46.4 21.0 14.0 10.5 8.45 6.98