SLVUCW7 September   2024 TPS1685

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5.   5
  6. 1Evaluation Module Overview
    1. 1.1 Introduction
    2. 1.2 Kit Contents
    3. 1.3 Specification
    4. 1.4 Device Information
  7. 2Hardware
    1. 2.1 General Configurations
      1. 2.1.1 Physical Access
      2. 2.1.2 Test Equipment and Setup
        1. 2.1.2.1 Power Supplies
        2. 2.1.2.2 Meters
        3. 2.1.2.3 Oscilloscope
        4. 2.1.2.4 Loads
  8. 3Implementation Results
    1. 3.1 Test Setup and Procedures
      1. 3.1.1  Hot Plug
      2. 3.1.2  Start-up with Enable
      3. 3.1.3  Power Up Into Short
      4. 3.1.4  Undervoltage Lockout
      5. 3.1.5  Overvoltage Lockout
      6. 3.1.6  Transient Overload Performance
      7. 3.1.7  Overcurrent Event
      8. 3.1.8  Output Hot Short
      9. 3.1.9  Quick Output Discharge (QOD)
      10. 3.1.10 Thermal Performance of TPS1685EVM
  9. 4Hardware Design Files
    1. 4.1 Schematics
    2. 4.2 PCB Drawings
    3. 4.3 Bill of Materials (BOM)
  10. 5Additional Information
    1. 5.1 Trademarks

3.1.8 Output Hot Short

Use the following instructions to perform the output hot short test:

  1. Set the input supply voltage VIN to 54V and connect the power supply between VIN (connector T1) and PGND (Connector T3).
  2. Configure the Jumper J7 in a good position to set the required scalable fast-trip threshold (ISFT) as per 7.
  3. Turn ON the power supply to power up the EVM.
  4. Short the output of the device for example, VOUT (connector T2) to PGND (connector T3) through a short cable.
  5. Observe the waveforms using an oscilloscope.

The test waveforms of output hot short on the TPS1685EVM with two TPS1685 eFuses in parallel are shown in Figure 3-10 and Figure 3-10.

TPS1685EVM Output Hot Short Response (zoomed out) in TPS1685EVM (VIN = 54V, RIMON = 1.1kΩ, RIREF = 40.2kΩ, RSFT = 150kΩ, and COUT = 1mF) Figure 3-9 Output Hot Short Response (zoomed out) in TPS1685EVM (VIN = 54V, RIMON = 1.1kΩ, RIREF = 40.2kΩ, RSFT = 150kΩ, and COUT = 1mF)
TPS1685EVM Output Hot Short Response (zoomed in) in TPS1685EVM (VIN = 54V, RIMON = 1.1kΩ, RIREF = 40.2kΩ, RSFT = 150kΩ, and COUT = 1mF)Figure 3-10 Output Hot Short Response (zoomed in) in TPS1685EVM (VIN = 54V, RIMON = 1.1kΩ, RIREF = 40.2kΩ, RSFT = 150kΩ, and COUT = 1mF)
Note: Make sure there is sufficient input capacitor to eliminate voltage dips at the input. A combination of electrolytic and ceramic capacitors are preferred. With these capacitors, a large current can be provided for a short period of time during short-circuit.

To obtain repeatable and similar short-circuit testing results is very difficult. The following contributes to the variation in results:

  • Source bypassing
  • Input leads
  • Board layout
  • Component selection
  • Output shorting method
  • Relative location of the short
  • Instrumentation

The actual short exhibits a certain degree of randomness because the short microscopically bounces and arcs. Make sure that configuration and methods are used to obtain realistic results. Hence, do not expect to see waveforms exactly like the waveforms in this user's guide because every setup is different.