SLVUCB8A May   2022  – September 2022 TPS25985

 

  1.   TPS25985 evaluation module for eFuse User's Guide
  2.   Trademarks
  3. 1Introduction
    1. 1.1 EVM Features
    2. 1.2 EVM Applications
  4. 2Description
  5. 3Schematic
  6. 4General Configurations
    1. 4.1 Physical Access
    2. 4.2 Test Equipment and Setup
      1. 4.2.1 Power supplies
      2. 4.2.2 Meters
      3. 4.2.3 Oscilloscope
      4. 4.2.4 Loads
  7. 5Test Setup and Procedures
    1. 5.1  Hot Plug
    2. 5.2  Start-up with Enable
    3. 5.3  Difference Between Current Limit and DVDT Based Start-up Mechanisms
    4. 5.4  Power-up into Short
    5. 5.5  Overvoltage Lockout
    6. 5.6  Transient Overload Performance
    7. 5.7  Overcurrent Event
    8. 5.8  Provision to Apply Load Transient and Overcurrent Event Using an Onboard Switching Circuit
    9. 5.9  Output Hot Short
    10. 5.10 PROCHOT# Implementation Using General-Purpose Comparator
    11. 5.11 Quick Output Discharge (QOD)
    12. 5.12 Thermal Performance of TPS25985EVM
  8. 6EVAL Board Assembly Drawings and Layout Guidelines
    1. 6.1 PCB Drawings
  9. 7Bill Of Materials (BOM)
  10. 8Revision History

5.3 Difference Between Current Limit and DVDT Based Start-up Mechanisms

Use the following instructions to perform the start-up with current limit test:
  1. Configure the jumper J2 position to the desired slew rate mentioned in Table 4-3.

  2. Configure the jumpers J5 and J7 positions to the desired current limits during start-up as mentioned in Table 4-3.

  3. Configure the Jumper J6 position to desired reference voltage for overcurrent protection and active current sharing as mentioned in Table 4-3.

  4. Set the input supply voltage VIN to 12 V and current limit to 100 A.
  5. Connect a load of 0.9 Ω between VOUT (Connector T2) and PGND (Connector T3).
  6. Connect the input supply between VIN (Connector T1) and PGND (Connector T3).
  7. Turn on the power supply by keeping the device disabled using the switch SW1.

  8. Enable the eFuse by releasing the switch SW1.

  9. Observe the waveform at VOUT (TP4) and input current using an oscilloscope. The main intention of this experiment is to observe the output voltage & input current profiles and time required to complete the inrush with two different ILIM set points having all other test conditions identical. The inrush current hits the current limit set point in one case, but does not in the next.

Figure 5-5 and Figure 5-6 show the difference between the current limit and DVDT based start-up mechanisms on the TPS25985EVM eFuse Evaluation Board having two (2) devices in parallel for RILIM of 680 and RLIM2 of 680 Ω and RILIM of 402 and RLIM2 of 402 Ω respectively.

Figure 5-5 Start-up with Current Limit Response of TPS25985 eFuse (VIN = 12 V, EN Stepped Up from 0 V to 3 V, RILIM = 680 Ω, RLIMI2 = 680 Ω, RIREF = 40.2 kΩ, COUT = 18.47 mF, RLOAD = 0.9 Ω, and CDVDT = 33 nF)
Figure 5-6 Start-up with Output Slew Rate Control (only) Response of TPS25985 eFuse (VIN = 12 V, EN Stepped Up from 0 V to 3 V, RILIM = 402 Ω, RILIM2 = 402 Ω, RIREF = 40.2 kΩ, COUT = 18.47 mF, RLOAD = 0.9 Ω, and CDVDT = 33 nF)