ZHCSQC2A November   2015  – July 2022 TPS51216-EP

PRODUCTION DATA  

  1. 1 特性
  2. 2 应用
  3. 3 说明
  4. 4 Revision History
  5. 5 说明（续）
  6. 6 Pin Configuration and 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 VDDQ Switch Mode Power Supply Control
      2. 8.3.2 VREF and REFIN, VDDQ Output Voltage
      3. 8.3.3 Soft-Start and Powergood
      4. 8.3.4 Power State Control
      5. 8.3.5 Discharge Control
      6. 8.3.6 VTT Overcurrent Protection
      7. 8.3.7 V5IN Undervoltage Lockout (UVLO) Protection
      8. 8.3.8 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 MODE Pin Configuration
  9. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 D-CAP Mode
      2. 9.1.2 Light-Load Operation
      3. 9.1.3 VTT and VTTREF
      4. 9.1.4 VDDQ Overvoltage and Undervoltage Protection
      5. 9.1.5 VDDQ Overcurrent Protection
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 List of Materials
        2. 9.2.2.2 External Components Selection
      3. 9.2.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 接收文档更新通知
    2. 12.2 支持资源
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 术语表
  13. 13Mechanical, Packaging, and Orderable Information

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9.1.5 VDDQ Overcurrent Protection

The VDDQ SMPS has cycle-by-cycle overcurrent limiting protection. The inductor current is monitored during the off-state using the low-side MOSFET RDS(on) and the controller maintains the off-state while the voltage across the low-side MOSFET is larger than the overcurrent trip level. The current monitor circuit inputs are PGND and SW pins so that those should be properly connected to the source and drain terminals of low-side MOSFET. The overcurrent trip level, VTRIP, is determined by Equation 4.

Equation 4. GUID-856B7233-095A-4EFF-ADCE-B68A6DAB1569-low.gif

where

  • RTRIP is the value of the resistor connected between the TRIP pin and GND
  • ITRIP is the current sourced from the TRIP pin. ITRIP is 10 μA typically at room temperature, and has 4700 ppm/°C temperature coefficient to compensate the temperature dependency of the low-side MOSFET RDS(on).

Because the comparison is done during the off-state, VTRIP sets the valley level of the inductor current. The load current OCL level, IOCL, can be calculated by considering the inductor ripple current as shown in Equation 5.

Equation 5. GUID-40D9A860-7470-40C5-AA9D-2FCF40F7DE41-low.gif

where

  • IIND(ripple) is inductor ripple current

In an overcurrent condition, the current to the load exceeds the current to the output capacitor, thus the output voltage tends to fall down. Eventually, it crosses the undervoltage protection threshold and shuts down.