SLUUCJ2 July   2021 UCC14240-Q1


  1.   Trademarks
  2. 1Introduction
    1. 1.1 Pin Configuration and Functions
  3. 2Description
    1. 2.1 EVM Electrical Performance Specifications
  4. 3Schematic
  5. 4EVM Setup and Operation
    1. 4.1 Reference
    2. 4.2 External Connections for Easy Evaluation
    3. 4.3 Powering the EVM
      1. 4.3.1 Power on for Start-up
      2. 4.3.2 Power off for Shutdown
    4. 4.4 EVM Test Points
    5. 4.5 Oscilloscope Probes: Probing the EVM
  6. 5 Performance Data
    1. 5.1 Efficiency Data
    2. 5.2 Regulation Data
    3. 5.3 Start-up Waveforms
    4. 5.4 Inrush Current
    5. 5.5 AC Ripple Voltage
    6. 5.6 EN and /PG Timing
    7. 5.7 Shutdown
    8. 5.8 Steady State
    9. 5.9 Thermal Performance
  7. 6Assembly and Printed Circuit Board (PCB) Layers
  8. 7Bill of Materials (BOM)
  9. 8Revision History

Oscilloscope Probes: Probing the EVM

Using TP4, TP6 and TP10 oscilloscope probe PCB test points: The UCC12240-Q1 is a high frequency DC-DC module that requires careful measurement for accurately capturing transient events and measuring high frequency, AC ripple voltage. Remove the “witch hat” probe tip cover and ground lead from the scope probe. If scope probe ground springs are not available, wrap a piece of 22 AWG bare wire around the scope probe ground ring and insert the probe tip and ground into the EVM as shown in Figure 4-5.


Figure 4-5 UCC14240EVM-052, PCB Scope Probe Test Points

The EVM output nomenclature (VDD, VEE, COM) corresponds to what is commonly used when referring to isolated gate driver ICs. As shown in Figure 3-1, TP5 (COM) is the midpoint of a capacitive divider and is intended to connect to the COM pin of the isolated gate driver IC. When the UCC14240-Q1 is used to bias a gate driver IC, VDD (VDD-COM) and VEE (VEE-COM) are referred to with respect to COM. In this case consider COM to be GND as it acts as a virtual GND to the gate driver IC. Because the midpoint of the capacitive divider is sensitive to charge imbalance, do not connect any ground-referenced, test equipment to TP5 (COM) when probing the EVM. A battery powered DVM can be used to measure VEE with respect to COM. When testing the EVM as a stand-alone bias power supply, limit oscilloscope probing of the secondary-side outputs to TP4 and TP6 which are referenced to VEE . As a result, VDD shows an oscilloscope measurement of VDD+|VEE| and VEE shows |VEE|. Connecting any ground-referenced test equipment to COM results in a false but safe overcurrent condition causing VDD and VEE to inadvertently drop out of regulation during light-load operation.