JAJSFU6C July   2018  – July 2019 LM5180

ADVANCE INFORMATION for pre-production products; subject to change without notice.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      代表的なアプリケーション
      2.      標準的な効率、VOUT = 5V
  4. 4 改訂履歴
  5. 5 概要（続き）
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 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  Integrated Power MOSFET
      2. 8.3.2  PSR Flyback Modes of Operation
      3. 8.3.3  Setting the Output Voltage
        1. 8.3.3.1 Diode Thermal Compensation
      4. 8.3.4  Control Loop Error Amplifier
      5. 8.3.5  Precision Enable
      6. 8.3.6  Configurable Soft Start
      7. 8.3.7  External Bias Supply
      8. 8.3.8  Minimum On-Time and Off-Time
      9. 8.3.9  Overcurrent Protection
      10. 8.3.10 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1: Wide VIN, Low IQ PSR Flyback Converter Rated at 5 V, 1 A
        1. 9.2.1.1 Design Requirements
        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  Custom Design With Excel Quickstart Tool
          3. 9.2.1.2.3  Flyback Transformer – T1
          4. 9.2.1.2.4  Flyback Diode – DFLY
          5. 9.2.1.2.5  Zener Clamp Circuit – DF, DCLAMP
          6. 9.2.1.2.6  Output Capacitor – COUT
          7. 9.2.1.2.7  Input Capacitor – CIN
          8. 9.2.1.2.8  Feedback Resistor – RFB
          9. 9.2.1.2.9  Thermal Compensation Resistor – RTC
          10. 9.2.1.2.10 UVLO Resistors – RUV1, RUV2
          11. 9.2.1.2.11 Soft-Start Capacitor – CSS
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Design 2: PSR Flyback Converter With Dual Outputs of 15 V and –7.7 V at 200 mA
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
          1. 9.2.2.2.1 Flyback Transformer – T1
          2. 9.2.2.2.2 Flyback Diodes – DFLY1 and DFLY2
          3. 9.2.2.2.3 Input Capacitor – CIN
          4. 9.2.2.2.4 Feedback Resistor – RFB
          5. 9.2.2.2.5 UVLO Resistors – RUV1, RUV2
        3. 9.2.2.3 Application Curves
      3. 9.2.3 Design 3: PSR Flyback Converter With Stacked Dual Outputs of 24 V and 5 V
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
          1. 9.2.3.2.1 Flyback Transformer – T1
          2. 9.2.3.2.2 Feedback Resistor – RFB
          3. 9.2.3.2.3 UVLO Resistors – RUV1, RUV2
        3. 9.2.3.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12デバイスおよびドキュメントのサポート
    1. 12.1 デバイス・サポート
      1. 12.1.1 デベロッパー・ネットワークの製品に関する免責事項
      2. 12.1.2 開発サポート
      3. 12.1.3 WEBENCH® ツールによるカスタム設計
    2. 12.2 ドキュメントのサポート
      1. 12.2.1 関連資料
    3. 12.3 ドキュメントの更新通知を受け取る方法
    4. 12.4 コミュニティ・リソース
    5. 12.5 商標
    6. 12.6 静電気放電に関する注意事項
    7. 12.7 Glossary
  13. 13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

8.3.5 Precision Enable

The precision EN/UVLO input supports adjustable input undervoltage lockout (UVLO) with hysteresis for application specific power-up and power-down requirements. EN/UVLO connects to a comparator with a 1.5-V reference voltage and 50-mV hysteresis. An external logic signal can be used to drive the EN/UVLO input to toggle the output on and off for system sequencing or protection. The simplest way to enable the LM5180 is to connect EN/UVLO directly to VIN. This allows the LM5180 to start up when VIN is within its valid operating range. However, many applications benefit from using a resistor divider RUV1 and RUV2 as shown in Figure 21 to establish a precision UVLO level.

LM5180 UVLOcircuit_nvsb06.gifFigure 21. Programmable Input Voltage UVLO With Hysteresis

Use Equation 10 and Equation 11 to calculate the input UVLO voltages turn-on and turn-off voltages, respectively, where VUV-RISING and VUV-FALLING are the UVLO comparator thresholds and IUV-HYST is the hysteresis current.

Equation 10. LM5180 q_Vin-on_nvsb06.gif
Equation 11. LM5180 q_Vin-off_nvsb06.gif

The LM5180 also provides a low-IQ shutdown mode when the EN/UVLO voltage is pulled below a base-emitter voltage drop (approximately 0.6 V at room temperature). If the EN/UVLO voltage is below this hard shutdown threshold, the internal LDO regulator powers off, and the internal bias-supply rail collapses, shutting down the bias currents of the LM5180. The LM5180 operates in standby mode when the EN/UVLO voltage is between the hard shutdown and precision-enable thresholds.