SLVUCH7A september   2022  – june 2023 TPS25990

 

  1.   1
  2.   TPS25990EVM: Evaluation Module for TPS25990 eFuse
  3.   Trademarks
  4. 1Introduction
    1. 1.1 EVM Features
    2. 1.2 EVM Applications
  5. 2Description
  6. 3Schematic
  7. 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 USB-to-GPIO Interface Adapter
      5. 4.2.5 Loads
  8. 5Test Setup and Procedures
    1. 5.1  Hot Plug
    2. 5.2  Start-up with Enable
    3. 5.3  Current Limit Based Start-up Behavior
    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 Quick Output Discharge (QOD)
    11. 5.11 Thermal Performance of TPS25990EVM
  9. 6Using the TPS25990EVM-GUI
    1. 6.1 Access the TPS25990EVM-GUI
    2. 6.2 Introduction to the TPS25990EVM-GUI
    3. 6.3 Establishing Communication Between the EVM and GUI
    4. 6.4 Quick Info
    5. 6.5 Configuration
    6. 6.6 Telemetry
    7. 6.7 Blackbox
    8. 6.8 Register Map Page
  10. 7EVAL Board Assembly Drawings and Layout Guidelines
    1. 7.1 PCB Drawings
  11. 8Bill Of Materials (BOM)
  12. 9Revision History

5.8 Provision to Apply Load Transient and Overcurrent Event Using an Onboard Switching Circuit

The TPS25990EVM provides an add-on circuit to facilitate load transients and persistent overcurrent events. The implementation consists of three low side MOSFETs (Q4, Q5, and Q6) and a mono-shot gate driver circuit (U7 and U8) as well as six onboard load resistors of 1 Ω each (R45 to R50) in parallel. Using a single pole single through (SPST) switch (S1), the mono-shot gate driver generates a gate signal lasting 1 ms, 2 ms, 5 ms, 10 ms, and 20 ms. By pressing the switch SW3, the low side MOSFETs are turned on for that specific duration, creating a load transient on the steady-state load above. Use the following instructions to apply a load transient or persistent overcurrent event using this onboard switching circuit:

  1. The overcurrent blanking timer duration (tTIMER) is 2.18 ms by default. The overcurrent blanking timer duration can be programmed via PMBus using the OC_TIMER (E6h) register if another timer duration is needed in the range of 0 ms to 27.8 ms.
  2. The reference voltage for overcurrent protection and active current sharing is at 1 V by default. The reference voltage can also be programmed via PMBus using the VIREF (E0h) register if another reference voltage is needed in the range of 0.3 V to 1.2 V.
  3. Configure the jumper J6 in a good position to set required circuit breaker threshold (IOCP) as per Table 4-3.
  4. Set the input supply voltage VIN to 12 V and current limit to 200 A.
  5. Connect the power supply between VIN (Connector T1) and PGND (Connector T3) and enable the power supply.
  6. Connect a steady-state load between VOUT (Connector T2) and PGND (Connector T3).
  7. Use the single pole single through (SPST) switch (S1) to configure the transient load turn on duration. Press the switch SW3 to turn on the Q4, Q5, and Q6 MOSFETs, which creates a load transient of 72 A (typical) between VOUT and PGND with 12 V output.
  8. Observe the waveforms of VOUT (TP4), MOSFET GATE (J9), and input current using an oscilloscope.

Another option is to apply a custom load transient using an external function generator, connected between TP30 and TP31, and the shunt of jumper J9 set to "2-3".

CAUTION: In that case, make sure to limit the transient load current magnitude to a safe level for reliable operation of the load resistors (R45 to R50) based on their maximum permissible peak pulse power vs pulse duration plot.

Figure 5-13 and Figure 5-14 show the test waveforms of transient overload and persistent overload events respectively using the onboard switching circuit.

GUID-20220913-SS0I-RFQJ-4THS-LW9VWBPFPTJV-low.svgFigure 5-13 Transient Overload Performance in TPS25990EVM Using the Onboard Switching Circuit (VIN = 12 V, tITIMER = 14 ms, COUT = 1470 μF, RIMON = 1.47 ∥ 1.1 kΩ, VIREF = 1 V, IOUT(Steady-State) = 85 A, and IOUT(Transient) = 65 A for 9 ms)
GUID-20220913-SS0I-WLXF-D7RC-XDQLGWQZFNBZ-low.svgFigure 5-14 Persistent Overload Performance in TPS25990EVM Using the Onboard Switching Circuit (VIN = 12 V, tITIMER = 14 ms, COUT = 1470 μF, RIMON = 1.47 ∥ 1.1 kΩ, VIREF = 1 V, IOUT(Steady-State) = 85 A, and IOUT(Transient) = 65 A for 18 ms)