JAJSGW9A January   2019  – August 2019 TPS560430-Q1

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.      効率と出力電流との関係VOUT = 5V、2100kHz、PFM
  4. 4 改訂履歴
  5. 5 Device Comparison Table
  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 Timing Requirements
    7. 7.7 Switching Characteristics
    8. 7.8 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 Fixed Frequency Peak Current Mode Control
      2. 8.3.2 Adjustable Output Voltage
      3. 8.3.3 Enable
      4. 8.3.4 Minimum ON-Time, Minimum OFF-Time and Frequency Foldback
      5. 8.3.5 Bootstrap Voltage
      6. 8.3.6 Over Current and Short Circuit Protection
      7. 8.3.7 Soft Start
      8. 8.3.8 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Active Mode
      3. 8.4.3 CCM Mode
      4. 8.4.4 Light-Load Operation (PFM Version)
      5. 8.4.5 Light-Load Operation (FPWM Version)
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Custom Design With WEBENCH® Tools
        2. 9.2.2.2 Output Voltage Set-Point
        3. 9.2.2.3 Switching Frequency
        4. 9.2.2.4 Inductor Selection
        5. 9.2.2.5 Output Capacitor Selection
        6. 9.2.2.6 Input Capacitor Selection
        7. 9.2.2.7 Bootstrap Capacitor
        8. 9.2.2.8 Under Voltage Lockout Set-Point
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Compact Layout for EMI Reduction
      2. 11.1.2 Feedback Resistors
    2. 11.2 Layout Example
  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 開発サポート
        1. 12.1.1.1 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

8.3.6 Over Current and Short Circuit Protection

The TPS560430-Q1 is protected from over-current conditions by cycle-by-cycle current limit on both the peak and valley of the inductor current. Hiccup mode is activated if a fault condition persists to prevent over-heating.

High-side MOSFET over-current protection is implemented by the nature of the Peak Current Mode control. The high-side switch current is sensed when the high-side is turned on after a set blanking time. The high-side switch current is compared to the output of the Error Amplifier (EA) minus slope compensation every switching cycle. Please refer to Functional Block Diagram for more details. The peak current of high-side switch is limited by a clamped maximum peak current threshold Ihigh side_LIMIT which is constant.

The current going through low-side MOSFET is also sensed and monitored. When the low-side switch turns on, the inductor current begins to ramp down. The low-side switch will not be turned OFF at the end of a switching cycle if its current is above the low-side current limit ILS_LIMIT. The low-side switch is kept ON so that inductor current keeps ramping down, until the inductor current ramps below the ILS_LIMIT. Then the low-side switch will be turned OFF and the high-side switch will be turned on after a dead time. This is somewhat different to the more typical peak current limit, and results in Equation 6 for the maximum load current.

Equation 6. TPS560430-Q1 slvse22-equation-6.gif

If the feedback voltage is lower than 40% of the VREF, the current of the low-side switch triggers ILS_LIMIT for 256 consecutive cycles, hiccup current protection mode is activated. In hiccup mode, the converter shuts down and keeps off for a period of hiccup, THICCUP (135 ms typical), before the TPS560430-Q1 tries to start again. If over-current or short-circuit fault condition still exist, hiccup repeats until the fault condition is removed. Hiccup mode reduces power dissipation under severe over-current conditions, prevents over-heating and potential damage to the device.

For FPWM version, the inductor current is allowed to go negative. When this current exceed the low-side negative current limit ILS_NEG, the low-side switch is turned off and high-side switch is turned on immediately. This is used to protect the low-side switch from excessive negative current.