JAJS013I December   2000  – September 2020 DCP010505B , DCP010505DB , DCP010507DB , DCP010512B , DCP010512DB , DCP010515B , DCP010515DB , DCP011512DB , DCP011515DB , DCP012405B , DCP012415DB

PRODUCTION DATA  

  1. 特長
  2. アプリケーション
  3. 概要
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagrams
    3. 7.3 Feature Description
      1. 7.3.1  Isolation
        1. 7.3.1.1 Operation or Functional Isolation
        2. 7.3.1.2 Basic or Enhanced Isolation
        3. 7.3.1.3 Continuous Voltage
        4. 7.3.1.4 Isolation Voltage
        5. 7.3.1.5 Repeated High-Voltage Isolation Testing
      2. 7.3.2  Power Stage
      3. 7.3.3  Oscillator And Watchdog Circuit
      4. 7.3.4  Thermal Shutdown
      5. 7.3.5  Synchronization
      6. 7.3.6  Light Load Operation (< 10%)
      7. 7.3.7  Load Regulation (10% to 100%)
      8. 7.3.8  Construction
      9. 7.3.9  Thermal Management
      10. 7.3.10 Power-Up Characteristics
    4. 7.4 Device Functional Modes
      1. 7.4.1 Disable and Enable (SYNCIN Pin)
      2. 7.4.2 Decoupling
        1. 7.4.2.1 Ripple Reduction
        2. 7.4.2.2 Connecting the DCP01B in Series
        3. 7.4.2.3 Connecting the DCP01B in Parallel
  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 Capacitor
        2. 8.2.2.2 Output Capacitor
        3. 8.2.2.3 SYNCIN Pin
      3. 8.2.3 DCP010505 Application Curves
      4. 8.2.4 PCB Design
      5. 8.2.5 Decoupling Ceramic Capacitors
      6. 8.2.6 Input Capacitor and the Effects of ESR
      7. 8.2.7 Ripple and Noise
        1. 8.2.7.1 Output Ripple Calculation Example
      8. 8.2.8 Dual DCP01B Output Voltage
      9. 8.2.9 Optimizing Performance
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Device Nomenclature
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Support Resources
    5. 11.5 Trademarks
    6. 11.6 Glossary
    7. 11.7 Electrostatic Discharge Caution
  12. 12Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ(パッケージ|ピン)
サーマルパッド・メカニカル・データ
発注情報

Decoupling Ceramic Capacitors

All capacitors have losses because of internal equivalent series resistance (ESR), and to a lesser degree, equivalent series inductance (ESL). Values for ESL are not always easy to obtain. However, some manufacturers provide graphs of frequency versus capacitor impedance. These graphs typically show the capacitor impedance falling as frequency is increased (as shown in Figure 8-4). In Figure 8-4, XC is the reactance due to the capacitance, XL is the reactance due to the ESL, and f0 is the resonant frequency. As the frequency increases, the impedance stops decreasing and begins to rise. The point of minimum impedance indicates the resonant frequency of the capacitor. This frequency is where the components of capacitance and inductance reactance are of equal magnitude. Beyond this point, the capacitor is not effective as a capacitor.

GUID-26568367-8AB5-4851-B028-70C21524C43F-low.gifFigure 8-4 Capacitor Impedance versus Frequency

However, there is a 180° phase difference resulting in cancellation of the imaginary component. The resulting effect is that the impedance at the resonant point is the real part of the complex impedance, namely, the value of the ESR. The output capacitor's resonant frequency must be higher than the default switching frequency (800 kHz) of the device to properly decouple noise at and below the switching frequency.

The effect of the ESR is to cause a voltage drop within the capacitor. The value of this voltage drop is simply the product of the ESR and the transient load current, as shown in Equation 1.

Equation 1. VIN = VPK – (ESR × ITR)

where

  • VIN is the voltage at the device input
  • VPK is the maximum value of the voltage on the capacitor during charge
  • ITR is the transient load current

The other factor that affects the performance is the value of the capacitance. However, for the input and the full wave outputs (single-output voltage devices), ESR is the dominant factor.