ZHCSTG6A July   2023  – October 2023 TPS25984

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5. 4 Revision History
  6. 5 说明（续）
  7. 6 Pin Configuration and Functions
  8. 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 Logic Interface
    7. 7.7 Timing Requirements
    8. 7.8 Switching Characteristics
    9. 7.9 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Undervoltage Protection
      2. 8.3.2  Insertion Delay
      3. 8.3.3  Overvoltage Protection
      4. 8.3.4  Inrush Current, Overcurrent, and Short-Circuit Protection
        1. 8.3.4.1 Slew Rate (dVdt) and Inrush Current Control
          1. 8.3.4.1.1 Start-Up Time Out
        2. 8.3.4.2 Steady-State Overcurrent Protection (Circuit-Breaker)
        3. 8.3.4.3 Active Current Limiting During Start-Up
        4. 8.3.4.4 Short-Circuit Protection
      5. 8.3.5  Analog Load Current Monitor (IMON)
      6. 8.3.6  Mode Selection (MODE)
      7. 8.3.7  Parallel Device Synchronization (SWEN)
      8. 8.3.8  Stacking Multiple eFuses for Unlimited Scalability
        1. 8.3.8.1 Current Balancing During Start-Up
      9. 8.3.9  Analog Junction Temperature Monitor (TEMP)
      10. 8.3.10 Overtemperature Protection
      11. 8.3.11 Fault Response and Indication (FLT)
      12. 8.3.12 Power-Good Indication (PG)
      13. 8.3.13 Output Discharge
      14. 8.3.14 FET Health Monitoring
      15. 8.3.15 Single Point Failure Mitigation
        1. 8.3.15.1 IMON Pin Single Point Failure
        2. 8.3.15.2 ILIM Pin Single Point Failure
        3. 8.3.15.3 IREF Pin Single Point Failure
        4. 8.3.15.4 ITIMER Pin Single Point Failure
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
      1. 9.1.1 Single Device, Standalone Operation
      2. 9.1.2 Multiple Devices, Parallel Connection
      3. 9.1.3 Multiple eFuses, Parallel Connection With PMBus
      4. 9.1.4 Digital Telemetry Using External Microcontroller
    2. 9.2 Typical Application: 12-V, 3.3-kW Power Path Protection in Data Center Servers
      1. 9.2.1 Application
      2. 9.2.2 Design Requirements
      3. 9.2.3 Detailed Design Procedure
      4. 9.2.4 Application Curves
    3. 9.3 Best Design Practices
    4. 9.4 Power Supply Recommendations
      1. 9.4.1 Transient Protection
      2. 9.4.2 Output short-Circuit Measurements
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Documentation Support
      1. 10.1.1 Related Documentation
    2. 10.2 支持资源
    3. 10.3 Trademarks
    4. 10.4 静电放电警告
    5. 10.5 术语表
  12. 11Mechanical, Packaging, and Orderable Information

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)

8.3.4.3 Active Current Limiting During Start-Up

The TPS25984x responds to output overcurrent conditions during start-up by actively limiting the current. The device constantly senses the current flowing through each one (IDEVICE) and provides an analog current output (IILIM) on the ILIM pin, which in turn produces a proportional voltage (VILIM) across the ILIM pin resistor (RILIM) as per Equation 9.

Equation 9. V I L I M = I D E V I C E × G I L I M × R I L I M

Where GILIM is the current monitor gain (IILIM : IDEVICE)

The overcurrent condition is detected by comparing this voltage against a threshold which is a scaled voltage (CLREFSAT) derived from the reference voltage (VIREF) on the IREF pin as presented in Equation 10.

Equation 10. C L R E F S A T = 0.7 × V I R E F 3

The reference voltage (VIREF) can be controlled in two ways, which sets the start-up current limit threshold (ILIM) accordingly.

  1. In the standalone mode of operation, the internal current source interacts with the external IREF pin resistor (RIREF) to generate the reference voltage as shown in Equation 11.
    Equation 11. V I R E F = I I R E F × R I R E F
  2. In a primary and secondary configuration, the primary eFuse or controller drives the voltage on the IREF pin to provide an external reference (VIREF).

The active current limit (ILIM) threshold during start-up can be calculated using Equation 12.

Equation 12. I I L I M = C L R E F S A T G I L I M × R I L I M

When the load current through the device during start-up exceeds ILIM, the device tries to regulate and hold the load current at ILIM.

During current regulation, the output voltage drops, resulting in increased device power dissipation across the FET. If the device internal temperature (TJ) exceeds the thermal shutdown threshold (TSD), the FET is turned off. After the part shuts down due to a TSD fault, it either stays latched off (TPS259840 variants) or restarts automatically after a fixed delay (TPS259841 variants). See Overtemperature protection section for more details on device response to overtemperature.

Note:

The active current limit block employs a foldback mechanism during start-up based on the output voltage (VOUT). When VOUT is below the foldback threshold (VFB), the current limit threshold is further lowered.