ZHCSR75 November   2022 TPSM82902

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Mode Selection and Device Configuration (MODE/S-CONF)
      2. 7.3.2 Adjustable VO Operation (External Voltage Divider)
      3. 7.3.3 Setable VO Operation (VSET and Internal Voltage Divider)
      4. 7.3.4 Soft Start/Tracking (SS/TR)
      5. 7.3.5 Smart Enable with Precise Threshold
      6. 7.3.6 Power Good (PG)
      7. 7.3.7 Undervoltage Lockout (UVLO)
      8. 7.3.8 Current Limit And Short Circuit Protection
      9. 7.3.9 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Pulse Width Modulation (PWM) Operation
      2. 7.4.2 AEE (Automatic Efficiency Enhancement)
      3. 7.4.3 Power Save Mode Operation (Auto PFM/PWM)
      4. 7.4.4 100% Duty-Cycle Operation
      5. 7.4.5 Output Discharge Function
      6. 7.4.6 Starting into a Pre-Biased Load
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application with Adjustable Output Voltage
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Custom Design With WEBENCH® Tools
        2. 8.2.2.2 Programming the Output Voltage
        3. 8.2.2.3 Capacitor Selection
          1. 8.2.2.3.1 Output Capacitor
          2. 8.2.2.3.2 Input Capacitor
          3. 8.2.2.3.3 Soft-Start Capacitor
        4. 8.2.2.4 Tracking Function
      3. 8.2.3 Application Curves
    3. 8.3 Typical Application with Setable VO Using VSET
      1. 8.3.1 Design Requirements
      2. 8.3.2 Detailed Design Procedure
      3. 8.3.3 Application Curves
    4. 8.4 Power Supply Recommendations
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
        1. 8.5.2.1 Thermal Considerations
  9. 9 Device and Documentation Support
    1. 9.1 Device Support
      1. 9.1.1 第三方产品免责声明
      2. 9.1.2 Development Support
        1. 9.1.2.1 Custom Design With WEBENCH® Tools
    2. 9.2 接收文档更新通知
    3. 9.3 支持资源
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 术语表
  10. 10Mechanical, Packaging, and Orderable Information

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7.3.8 Current Limit And Short Circuit Protection

The TPSM82902 is protected against overload and short circuit events. If the inductor current exceeds the high-side FET current limit (ILIMH), the high-side switch is turned off and the low-side switch is turned on to ramp down the inductor current. The high-side FET turns on again only if the current in the low-side FET has decreased below the low-side FET current limit threshold.

Due to internal propagation delay, the actual current can exceed the static current limit during that time. The dynamic current limit is given as Equation 1:

Equation 1. GUID-3F358AEC-E394-4983-B16D-03DC1C9A72D7-low.gif

where

  • ILIMH is the static high-side FET current limit as specified in the Electrical Characteristics.
  • L is the effective inductance at the peak current (approximately 0.9 μH).
  • VL is the voltage across the inductor (VIN – VOUT).
  • tPD is the internal propagation delay of typically 50 ns.

The current limit can exceed static values, especially if the input voltage is high and very small inductances are used. The dynamic high-side switch peak current can be calculated as follows:

Equation 2. GUID-9F95E2F1-6E52-47C5-8FAF-9CAC28A0546A-low.gif