SLVSHR9 December   2024 TPS25984B

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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 Logic Interface
    7. 6.7 Timing Requirements
    8. 6.8 Switching Characteristics
    9. 6.9 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Undervoltage Protection
      2. 7.3.2  Insertion Delay
      3. 7.3.3  Overvoltage Protection
      4. 7.3.4  Inrush Current, Overcurrent, and Short-Circuit Protection
        1. 7.3.4.1 Slew Rate (dVdt) and Inrush Current Control
          1. 7.3.4.1.1 Start-Up Time Out
        2. 7.3.4.2 Steady-State Overcurrent Protection (Circuit-Breaker)
        3. 7.3.4.3 Active Current Limiting During Start-Up
        4. 7.3.4.4 Short-Circuit Protection
      5. 7.3.5  Analog Load Current Monitor (IMON)
      6. 7.3.6  Mode Selection (MODE)
      7. 7.3.7  Digital Overcurrent Indication (D_OC)
      8. 7.3.8  Stacking Multiple eFuses for Scalability
        1. 7.3.8.1 Current Balancing During Start-Up
      9. 7.3.9  Analog Junction Temperature Monitor (TEMP)
      10. 7.3.10 Overtemperature Protection
      11. 7.3.11 Fault Response and Indication (GOK/FLT)
      12. 7.3.12 Power-Good Indication (PG)
      13. 7.3.13 Output Discharge
      14. 7.3.14 FET Health Monitoring
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Single Device, Standalone Operation
      2. 8.1.2 Multiple Devices, Parallel Connection
      3. 8.1.3 Digital Telemetry Using External Microcontroller
    2. 8.2 Typical Application: 12V, 3.3kW Power Path Protection in Data Center Servers
      1. 8.2.1 Application
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
      4. 8.2.4 Application Curves
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Transient Protection
      2. 8.3.2 Output Short-Circuit Measurements
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.3.4.2 Steady-State Overcurrent Protection (Circuit-Breaker)

The TPS25984Bx responds to output overcurrent conditions during steady-state by performing a circuit-breaker action after an internal transient fault blanking interval. This action allows the device to support a higher peak current for a short interval but also ensures robust protection in case of persistent output faults.

The device constantly senses the output load current and provides an analog current output (IILIM) on the ILIM pin which is proportional to the load current, which in turn produces a proportional voltage (VILIM) across the ILIM pin resistor (RILIM) as per Equation 28.

Equation 5. VILIM=IOUT×GILIM×RILIM

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

The overcurrent condition is detected by comparing this voltage against the voltage on the IREF pin as a reference. The reference voltage (VIREF) can be controlled in two ways, which sets the overcurrent protection threshold (IOCP) accordingly.

  • The internal current source interacts with the external IREF pin resistor (RIREF) to generate the reference voltage as shown in Equation 6.
    Equation 6. VIREF=IIREF×RIREF
  • It is also possible to drive the IREF pin from an external low impedance reference voltage source.

The overcurrent protection threshold during steady-state (IOCP) can be calculated using Equation 29.

Equation 7. IOCP=0.75 × VIREFGILIM×RILIM
Note:

Maintain VIREF within the recommended voltage range to ensure proper operation of the overcurrent detection circuit.

TI recommends to add a 150pF capacitor from IREF pin to GND for improved noise immunity.

After an overcurrent condition is detected, that is the load current exceeds the programmed current limit threshold (IOCP), but stays lower than the short-circuit threshold (2 × IOCP or IFFT whichever is lower), the device starts an internal blanking timer. If the load current drops below the current limit threshold before the timer expires, the circuit-breaker action is not engaged. This action allows transient load pulses to pass through the device without tripping the circuit. If the overcurrent condition persists for longer than the timer duration (tITIMER), the circuit-breaker action turns off the FET immediately.

Equation 8 can be used to calculate the RILIM value for the desired overcurrent threshold.

Equation 8. RILIM=0.75×VIREFGILIM×IOCP

Figure 7-4 illustrates the overcurrent response for TPS25984Bx eFuse. After the part shuts down due to a circuit-breaker fault, it either stays latched off (TPS25984B2 variant with MODE pin floating or TPS25984B0/3 variants) or restarts automatically after a fixed delay (TPS25984B2 variant with MODE pin connected to GND or TPS25984B1 variant).

TPS25984B Steady-State Overcurrent (Circuit-Breaker) ResponseFigure 7-4 Steady-State Overcurrent (Circuit-Breaker) Response