ZHCSU09H July   2004  – December 2023 LP2981 , LP2981A

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Output Enable
      2. 6.3.2 Dropout Voltage
      3. 6.3.3 Current Limit
      4. 6.3.4 Undervoltage Lockout (UVLO)
      5. 6.3.5 Thermal Shutdown
      6. 6.3.6 Output Pulldown
    4. 6.4 Device Functional Modes
      1. 6.4.1 Device Functional Mode Comparison
      2. 6.4.2 Normal Operation
      3. 6.4.3 Dropout Operation
      4. 6.4.4 Disabled
  8. 7 Application and Implementation
    1. 7.1 Application Information
      1. 7.1.1 Recommended Capacitor Types
        1. 7.1.1.1 Recommended Capacitors for the Legacy Chip
          1. 7.1.1.1.1 Tantalum Capacitors
          2. 7.1.1.1.2 Ceramic Capacitors
          3. 7.1.1.1.3 Aluminum Capacitors
        2. 7.1.1.2 Recommended Capacitors for the New Chip
      2. 7.1.2 Input and Output Capacitor Requirements
        1. 7.1.2.1 Input Capacitor
        2. 7.1.2.2 Output Capacitor
      3. 7.1.3 Estimating Junction Temperature
      4. 7.1.4 Power Dissipation (PD)
      5. 7.1.5 Reverse Current
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 ON and OFF Input Operation
      3. 7.2.3 Application Curves
  9. 8 Power Supply Recommendations
  10. 9 Layout
    1. 9.1 Layout Guidelines
    2. 9.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Device Nomenclature
    2. 10.2 Documentation Support
      1. 10.2.1 Related Documentation
    3. 10.3 Receiving Notification of Documentation Updates
    4. 10.4 支持资源
    5. 10.5 Trademarks
    6. 10.6 静电放电警告
    7. 10.7 术语表
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

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7.2.2.1 ON and OFF Input Operation

The LP2981/A is shut off by pulling the ON/ OFF input low, and turned on by driving the input high. If this feature is not to be used, the ON/OFF input must be tied to VIN to keep the regulator on at all times (the ON/ OFF input must not be left floating).

For proper operation, the signal source used to drive the ON/ OFF input must be able to swing above and below the specified turn-on or turn-off voltage thresholds which specify an ON or OFF state (see Section 5.5).

The ON/ OFF signal can come from either a totem-pole output, or an open-collector output with pullup resistor to the LP2981 and LP2891A input voltage or another logic supply. The high-level voltage can exceed the LP2981 and LP2891A input voltage, but must remain within the ratings list in Section 5.1 for the ON/ OFF pin.