SLVSEI3D October   2018  – May 2026 TPS25982

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 Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 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 (UVLO and UVP)
      2. 7.3.2 Overvoltage Protection (OVP)
      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 Circuit Breaker
        3. 7.3.3.3 Active Current Limiting
        4. 7.3.3.4 Short-Circuit Protection
      4. 7.3.4 Overtemperature Protection (OTP)
      5. 7.3.5 Analog Load Current Monitor (IMON)
      6. 7.3.6 Power Good (PG)
      7. 7.3.7 Load Detect/Handshake (LDSTRT)
    4. 7.4 Fault Response
    5. 7.5 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application: Standby Power Rail Protection in Datacenter Servers
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Device Selection
        2. 8.2.2.2 Setting the Current Limit Threshold: RILIM Selection
        3. 8.2.2.3 Setting the Undervoltage Lockout Set Point
        4. 8.2.2.4 Selecting the Current Monitoring Resistor: RIMON
        5. 8.2.2.5 Setting the Output Voltage Ramp Time (TdVdt)
          1. 8.2.2.5.1 Case 1: Start-Up Without Load: Only Output Capacitance COUT Draws Current
          2. 8.2.2.5.2 Case 2: Start-Up With Load: Output Capacitance COUT and Load Draw Current
        6. 8.2.2.6 Setting the Load Handshake (LDSTRT) Delay
        7. 8.2.2.7 Setting the Transient Overcurrent Blanking Interval (tITIMER)
        8. 8.2.2.8 Setting the Auto-Retry Delay and Number of Retries
      3. 8.2.3 Application Curves
    3. 8.3 System Examples
      1. 8.3.1 Optical Module Power Rail Path Protection
        1. 8.3.1.1 Design Requirements
        2. 8.3.1.2 Device Selection
        3. 8.3.1.3 External Component Settings
        4. 8.3.1.4 Voltage Drop
        5. 8.3.1.5 Application Curves
      2. 8.3.2 Input Protection for 12V Rail Applications: PCIe Cards, Storage Interfaces and DC Fans
    4. 8.4 Power Supply Recommendations
      1. 8.4.1 Transient Protection
      2. 8.4.2 Output Short-Circuit Measurements
    5. 8.5 Layout
      1. 8.5.1 Layout Guidelines
      2. 8.5.2 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

7.4 Fault Response

The following events trigger an internal fault which causes the device to shut down:

  • Overtemperature Protection
  • Circuit Breaker Operation
  • ITIMER pin Short to GND
  • ILIM pin Short to GND
Once the device shuts down due to a fault, even if the associated external fault is subsequently cleared, the fault stays latched internally and the output cannot turn on again until the latch is reset. The fault latch can be externally reset by one of the following methods:
  • Input supply voltage is driven low (< VUVP(F))
  • EN/UVLO voltage is driven low (< VSD)
The fault latch can also be reset by an internal auto-retry logic. The user can either disable the auto-retry behavior completely (latch-off behavior) or configure the device to auto-retry indefinitely or for a limited number of times before latching off. The auto-retry behavior is controlled by the connections on the RETRY_DLY and NRETRY pins.

Table 7-3 Pin Configurable Fault Response
EN/UVLORETRY_DLYNRETRYDEVICE STATE
LXXDisabled
HShort to GNDXNo auto-retry (Latch-off)
HOpenOpenAuto-retry 4 times with minimum delay between retries and then latch-off
HOpenShort to GNDAuto-retry indefinitely with minimum delay between retries
HCapacitor to GNDCapacitor to GNDAuto-retry delay and count as per Equation 14 and Equation 15
HCapacitor to GNDOpenAuto-retry 4 times with finite delay between retries as per Equation 14 and then latch-off
HCapacitor to GNDShort to GNDAuto-retry indefinitely with finite delay between retries as per Equation 14

To configure the part for a finite number of auto-retries with a finite auto-retry delay, first select the capacitor value on RETRY_DLY pin using the following equation.

Equation 14. t R E T R Y _ D L Y μ s = 128 × C R E T R Y _ D L Y p F + 4 p F × V R E T R Y _ D L Y _ H Y S V I R E T R Y _ D L Y μ A

Next, select the capacitor value on the NRETRY pin using the following equation.

Equation 15. N R E T R Y = 4 × I R E T R Y _ D L Y μ A × C N R E T R Y p F I N R E T R Y μ A × C R E T R Y _ D L Y p F + 4 p F

The number of auto-retries is quantized to certain discrete levels as shown in Table 7-4 .

Table 7-4 NRETRY Quantization Levels
NRETRY Calculated From Equation 15NRETRY Actual
0 < N < 44
4 < N < 1616
16 < N < 6464
64 < N < 256256
256 < N < 10241024
Table 7-5 NRETRY and RETRY_DLY Combination Examples
Auto Retry Delay915ms416ms91.7ms9.3ms3ms
RETRY_DLY Capacitor22nF10nF2.2nF220pF68pF
No. of Auto RetriesNRETRY Capacitor
4Open
1647nF22nF4.7nF1nF220pF
640.22μF0.1μF22nF2.2nF1nF
2561μF0.47μF0.1μF10nF4.7nF
10243.3μF1.5μF0.47μF33nF10nF
InfiniteShort to GND

A spreadsheet design tool TPS25982xx Design Calculator is also available for simplified calculations.

TPS25982 Auto-Retry After FaultFigure 7-10 Auto-Retry After Fault

The auto-retry logic has a mechanism to reset the count to zero if two consecutive faults occur far apart in time. This ensures that the auto-retry response to any later fault is handled as a fresh sequence and not as a continuation of the previous fault. If the fault which triggered the shutdown and subsequent auto-retry cycle is cleared eventually and does not occur again for a duration equal to 7 retry delay timer periods starting from the last fault, the auto-retry logic resets the internal auto-retry count to zero.