ZHCSQ76 December   2022 TPS25961

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 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 典型特性
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 欠压保护 (UVP) 和欠压锁定 (UVLO)
      2. 7.3.2 Overvoltage Protection
      3. 7.3.3 Inrush Current, Overcurrent and Short Circuit Protection
        1. 7.3.3.1 Slew Rate and Inrush Current Control (dVdt)
        2. 7.3.3.2 Active Current Limiting
        3. 7.3.3.3 Short-Circuit Protection
      4. 7.3.4 Overtemperature Protection (OTP)
      5. 7.3.5 Fault Response
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 典型应用
      1. 8.2.1 Adapter input protection for set-top boxes
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Programming the Current-Limit Threshold: RILM Selection
        2. 8.2.3.2 欠压和过压锁定设定点
        3. 8.2.3.3 Output Voltage Rise Time (tR)
      4. 8.2.4 Application Curves
    3. 8.3 Application Example
      1. 8.3.1 Application Curves
    4. 8.4 Power Supply Recommendations
      1. 8.4.1 瞬态保护
      2. 8.4.2 Output Short-Circuit Measurements
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 Layout Example
  9. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 接收文档更新通知
    3. 9.3 支持资源
    4. 9.4 商标
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 术语表
  10. 10Mechanical, Packaging, and Orderable Information

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7.3.3.2 Active Current Limiting

The device responds to output overcurrent conditions by actively limiting the current.

GUID-20220623-SS0I-8P0G-TVSC-HLJ3RHSSQG4P-low.gif Figure 7-5 TPS25961 Overcurrent Response

In the current limiting state, the output voltage drops resulting in increased power dissipation in the internal FET leading to thermal shutdown if the condition persists for an extended period of time. In this case, the device performs 3 auto-retry attempts to allow the system to recover and then latches-off if the fault persists. See Fault response section for more details on device response after a fault.

The current limit threshold can be adjusted by pinstrapping the ILIM pin.

Use equation below to calculate the RILIM value for overcurrent thresholds < 200 mA.

Equation 4. R ILIM   =  50000 I LIM   - 0.000002

Use equation below to calculate the RILIM value for overcurrent thresholds ≥ 200 mA.

Equation 5. R ILIM   =  50000 I LIM  
Note:
  1. Leaving the ILIM pin open sets the current limit to its minimum value.
  2. The device scales the FET ON resistance in discrete steps according to the RILIM setting to provide optimum performance for the desired current level. At higher ILIM settings, the ON resistance is lower and at lower ILIM settings, the ON resistance is higher. However, for certain RILIM resistor values, the device may select an incorrect ON resistance scaling which is too high for the target load current leading to excessive voltage drop and power dissipation. To avoid this situation, it's recommended to avoid certain RILIM values as per Table 7-1.

Table 7-1 RILIM Values to Avoid
ILIM Resistor Value Device ON Resistance
250 kΩ < RILIM < 500 kΩ Undefined
111 kΩ < RILIM < 142 kΩ Undefined
58.8 kΩ < RILIM < 66.7 kΩ Undefined