ZHCSLK4S July   2004  – May 2025 LP2985 , LP2985A

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 Diagrams
    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 Output Pulldown
      6. 6.3.6 Thermal Shutdown
    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 (Legacy Chip)
        2. 7.1.1.2 Recommended Capacitors (New Chip)
      2. 7.1.2 Input and Output Capacitor Requirements
        1. 7.1.2.1 Input Capacitor Requirements
        2. 7.1.2.2 Output Capacitor Requirements
      3. 7.1.3 Noise Bypass Capacitor (CBYPASS)
      4. 7.1.4 Reverse Current
      5. 7.1.5 Power Dissipation (PD)
      6. 7.1.6 Estimating Junction Temperature
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 ON/OFF Operation
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Device Nomenclature
    2. 8.2 接收文档更新通知
    3. 8.3 支持资源
    4. 8.4 Trademarks
    5. 8.5 静电放电警告
    6. 8.6 术语表
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

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7.1.2.1 Input Capacitor Requirements

For the legacy chip, a minimum value of 1μF (over the entire operating temperature range) is required at the input of the LP2985. In addition, place this input capacitor within 1cm of the input pin, connected to a clean analog ground. There are no equivalent series resistance (ESR) requirements for this capacitor; increase capacitance without limit.

For the new chip, although an input capacitor is not required for stability, good analog design practice is to connect a capacitor from IN to GND. This capacitor counteracts reactive input sources and improves transient response, input ripple, and PSRR. Use an input capacitor if the source impedance is more than 0.5Ω. Use a higher value capacitor if large, fast rise-time load or line transients are anticipated. Use this capacitor if the device is located several inches from the input power source.