JAJSG02D August   2012  – August 2018 LMZ21700

PRODUCTION DATA.  

  1. 1 特長
  2. 2 アプリケーション
  3. 3 概要
    1.     Device Images
      1.      概略回路図
      2.      VIN = 12Vでの効率
  4. 4 改訂履歴
  5. 5 Pin Configuration and Functions
    1. Table 1. Pin Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 Handling Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Package Construction
    4. 7.4 Feature Description
      1. 7.4.1 Input Under Voltage Lockout
      2. 7.4.2 Enable Input (EN)
      3. 7.4.3 Softstart and Tracking Function (SS)
      4. 7.4.4 Power Good Function (PG)
      5. 7.4.5 Output Voltage Setting
      6. 7.4.6 Output Current Limit and Output Short Circuit Protection
      7. 7.4.7 Thermal Protection
    5. 7.5 Device Functional Modes
      1. 7.5.1 PWM Mode Operation
      2. 7.5.2 PSM Operation
  8. 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 (CIN)
        2. 8.2.2.2 Output Capacitor (COUT)
        3. 8.2.2.3 Softstart Capacitor (CSS)
        4. 8.2.2.4 Power Good Resistor (RPG)
        5. 8.2.2.5 Feedback Resistors (RFBB and RFBT)
      3. 8.2.3 Application Curves
        1. 8.2.3.1 VOUT = 1.2 V
        2. 8.2.3.2 VOUT = 1.8 V
        3. 8.2.3.3 VOUT = 2.5 V
        4. 8.2.3.4 VOUT = 3.3 V
        5. 8.2.3.5 VOUT = 5.0 V
    3. 8.3 Do's and Don'ts
  9. 9 Power Supply Recommendations
    1. 9.1 Voltage Range
    2. 9.2 Current Capability
    3. 9.3 Input Connection
      1. 9.3.1 Voltage Drops
      2. 9.3.2 Stability
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Minimize the High di/dt Loop Area
      2. 10.1.2 Protect the Sensitive Nodes in the Circuit
      3. 10.1.3 Provide Thermal Path and Shielding
    2. 10.2 Layout Example
      1. 10.2.1 High Density Layout Example for Space Constrained Applications
        1. 10.2.1.1 35 mm² Solution Size (Single Sided)
  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
    2. 11.2 開発サポート
      1. 11.2.1 WEBENCH®ツールによるカスタム設計
    3. 11.3 ドキュメントの更新通知を受け取る方法
    4. 11.4 コミュニティ・リソース
    5. 11.5 商標
    6. 11.6 静電気放電に関する注意事項
    7. 11.7 Glossary
  12. 12メカニカル、パッケージ、および注文情報
    1. 12.1 Tape and Reel Information

パッケージ・オプション

デバイスごとのパッケージ図は、PDF版データシートをご参照ください。

メカニカル・データ（パッケージ｜ピン）
  • SIL|8
サーマルパッド・メカニカル・データ
発注情報

7.4.3 Softstart and Tracking Function (SS)

When EN is set high for device operation the LMZ21700 will start switching after 50 μs delay and the output voltage will start rising. The VOUT rising slope is controlled by the external capacitor CSS connected to the softstart (SS) pin. The nano module has a 2.5 μA constant current source internally connected to the SS pin to program the softstart time TSS:

Equation 1. TSS = CSS x 1.25 V / 2.5 μA

The softstart capacitor voltage is reset to zero volts when EN is pulled low and when the thermal protection is active.

If tracking function is desired, the SS pin can be used to track external voltage. If the applied external tracking voltage is between 100 mV and 1.2 V, the FB voltage will follow SS according to the following relationship:

Equation 2. VFB = 0.64 x VSS