TIDT293 October   2022

 

  1.   Description
  2.   Features
  3.   Applications
  4. 1Design Variants
  5. 2Design Overview
    1. 2.1 Board Contents
    2. 2.2 Connector Description
    3. 2.3 User Interface
      1. 2.3.1 Switches and Push-buttons
      2. 2.3.2 Jumpers
      3. 2.3.3 Potentiometers
    4. 2.4 Functional Block Diagram
    5. 2.5 Functional Block Descriptions
  6. 3Features and Performance Curves
    1. 3.1  Test Setup
    2. 3.2  Pulse
    3. 3.3  Levels and Free Run
    4. 3.4  INP
    5. 3.5  Dual-Output Power Supply
    6. 3.6  Overtemperature Protection
    7. 3.7  Slew Rate Adjust
    8. 3.8  Settling Time Adjust
    9. 3.9  Low- and High-Level Adjust
    10. 3.10 Pulse-Width Adjust
    11. 3.11 Period and Delay Adjust
    12. 3.12 Frequency Response
  7. 4Operation
    1. 4.1 Initial Setup – Jumper Selection and Potentiometer Settings
    2. 4.2 Procedure
      1. 4.2.1 Initial Power Up
      2. 4.2.2 Connecting the Circuit Under Test
  8. 5Limitations and Capabilities
    1. 5.1 Wiring Inductance
    2. 5.2 Minimum Voltage
    3. 5.3 Battery Life
  9. 6Typical Failure Mechanism
    1. 6.1 Fast Thermal Failure
    2. 6.2 Slow Thermal Failure

5.1 Wiring Inductance

When adjusting to a lower voltage, the load-step current is limited by the wiring inductance and slew rate of the setup. The following scope plot is a 1-A to 10-A load transient for a 1-V output. There is about a 0.7 V voltage drop, leaving 0.3 V for the MOSFET and sense resistor. Use short wires soldered directly to the load step board to reduce wiring inductance. The results in the following waveform use a PSMN008-75B MOSFET in the 125-A variant.

GUID-20220531-SS0I-JMRP-WBFJ-SRWHCRGWMTHD-low.pngFigure 5-1 Wiring Inductance Voltage Drop 1 A to 10 A, 1-V Output Load Transient

A larger load step causes the MOSFET voltage to collapse, resulting in an abnormal load transient. The following scope plot is a 1-A to 15-A load transient for a 1-V output.

GUID-20220531-SS0I-M7DL-ZP2L-56K1MBHF1XK5-low.pngFigure 5-2 Wiring Inductance Voltage Drop 1 A to 15 A, 1-V Output Load Transient