JAJS843E April   1998  – June 2019 LM2588

PRODUCTION DATA.  

  1. 1 特長
  2. 2 代表的なアプリケーション
  3. 3 概要
    1.     Device Images
      1.      フライバック・レギュレータ
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Pin Configurations
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Ratings
    4. 7.4 Electrical Characteristics: 3.3 V
    5. 7.5 Electrical Characteristics: 5 V
    6. 7.6 Electrical Characteristics: 12 V
    7. 7.7 Electrical Characteristics: Adjustable
    8. 7.8 Electrical Characteristics: All Output Voltage Versions
    9. 7.9 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Flyback Regulator Operation
      2. 8.3.2 Step-Up (Boost) Regulator Operation
      3. 8.3.3 Shutdown Control
      4. 8.3.4 Frequency Adjustment
      5. 8.3.5 Frequency Synchronization
      6. 8.3.6 Programming Output Voltage (Selecting R1 And R2)
      7. 8.3.7 Short-Circuit Condition
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical Flyback Regulator Applications
        1. 9.2.1.1 Design Requirements
          1. 9.2.1.1.1 Transformer Selection (T)
          2. 9.2.1.1.2 Transformer Footprints
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2 Flyback Regulator Input Capacitors
          3. 9.2.1.2.3 Switch Voltage Limits
          4. 9.2.1.2.4 Output Voltage Limitations
          5. 9.2.1.2.5 Noisy Input Line Condition
          6. 9.2.1.2.6 Stability
      2. 9.2.2 Typical Boost Regulator Applications
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
    3. 9.3 System Examples
      1. 9.3.1 Test Circuits
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Heat Sink/Thermal Considerations
  11. 11デバイスおよびドキュメントのサポート
    1. 11.1 デバイス・サポート
      1. 11.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 11.1.2 開発サポート
        1. 11.1.2.1 WEBENCH®ツールによるカスタム設計
    2. 11.2 ドキュメントの更新通知を受け取る方法
    3. 11.3 コミュニティ・リソース
    4. 11.4 商標
    5. 11.5 静電気放電に関する注意事項
    6. 11.6 Glossary
  12. 12メカニカル、パッケージ、および注文情報

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

8.3.4 Frequency Adjustment

The switching frequency of the LM2588 can be adjusted with the use of an external resistor. This feature allows the user to optimize the size of the magnetics and the output capacitor(s) by tailoring the operating frequency. A resistor connected from pin 1 (the Freq. Adj. pin) to ground will set the switching frequency from 100 kHz to 200 kHz (maximum). As shown in Figure 20, the pin can be used to adjust the frequency while still providing the shut down function. A curve in the Performance Characteristics Section graphs the resistor value to the corresponding switching frequency. The table in Table 1 shows resistor values corresponding to commonly used frequencies.

However, changing the LM2588's operating frequency from its nominal value of 100 kHz changes the magnetics selection and compensation component values.

Table 1. Frequency Setting Resistor Guide

RSET(kΩ) FREQUENCY (kHz)
Open 100
200 125
47 150
33 175
22 200