ZHCSP75A July   2022  – December 2022 TPS1HC30-Q1

PRODUCTION DATA  

  1. 特性
  2. 应用
  3. 说明
  4. Revision History
  5. Pin Configuration and Functions
  6. Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 建议运行条件
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 SNS Timing Characteristics
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. Parameter Measurement Information
  8. Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Accurate Current Sense
      2. 8.3.2 Programmable Current Limit
        1. 8.3.2.1 Capacitive Charging
      3. 8.3.3 Inductive-Load Switching-Off Clamp
      4. 8.3.4 Full Protections and Diagnostics
        1. 8.3.4.1  Short-Circuit and Overload Protection
        2. 8.3.4.2  Open-Load and Short-to-Battery Detection
        3. 8.3.4.3  Short-to-Battery Detection
        4. 8.3.4.4  Reverse-Polarity and Battery Protection
        5. 8.3.4.5  Latch-Off Mode
        6. 8.3.4.6  Thermal Protection Behavior
        7. 8.3.4.7  UVLO Protection
        8. 8.3.4.8  Loss of GND Protection
        9. 8.3.4.9  Loss of Power Supply Protection
        10. 8.3.4.10 Reverse Current Protection
        11. 8.3.4.11 Protection for MCU I/Os
      5. 8.3.5 Diagnostic Enable Function
    4. 8.4 Device Functional Modes
      1. 8.4.1 Working Mode
  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 Dynamically Changing Current Limit
        2. 9.2.2.2 EMC Transient Disturbances Test
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
        1. 9.4.2.1 Without a GND Network
        2. 9.4.2.2 With a GND Network
      3. 9.4.3 Thermal Considerations
  10. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 接收文档更新通知
    3. 10.3 支持资源
    4. 10.4 Trademarks
    5. 10.5 静电放电警告
    6. 10.6 术语表
  11. 11Mechanical, Packaging, and Orderable Information

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Dynamically Changing Current Limit

The current limit threshold can be changed dynamically by altering the resistance going from the current limit pin to the ground of the device on the fly. This alteration allows the system to have a different current limit for start-up, when there can be significant inrush current, and during normal operation. The way this is commonly done is by putting two resistors in parallel on the ILIM pin and having a switch to enable or disable one of the resistors. This set-up can be seen in Figure 9-2. Alternatively, a digital potentiometer can be used to adjust the impedance on the ILIM pin on the fly. Care must be taken so that the capacitance on the ILIM pin is below approximately 100 pF to keep the current regulation loop stable. The most common application where this feature is useful is capacitive loads.

Figure 9-2 Dynamic Changing Current Limit Setup

In a capacitive charging case, the initial current to charge the capacitor is the inrush current. Depending on the system requirements, dynamically changing the current limit can help either charge up a capacitor faster or charge up a larger capacitor. To allow a higher inrush level of current through in the beginning, the switch can be closed making the current limit be according to the equation below.

Equation 16. ILIM2 = KCL(RILIM1 + RILIM2) / (RILIM1 × RILIM2)

When the inrush event is over and the output voltage is charged up, the switch opens and the current limit is just the RILIM1 equivalent level. This timing can be seen in Figure 9-3.

Figure 9-3 Capacitive Charging Changing Current Limit

Alternatively, if the switch is open, the current limit starts out at a lower value and then the switch can be closed when the capacitance gets charged up. This lower current limit level allows higher value capacitance to be charged up. The timing diagram can be seen in Figure 9-4.

Figure 9-4 Large Capacitive Charging Changing Current Limit