TIDT320A january   2023  – july 2023

 

  1.   1
  2.   Description
  3.   Features
  4.   Applications
  5. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Functional Block Diagram
    3. 1.3 Pin Functions
  6. 2Waveforms
    1. 2.1 Switching Frequency and Operating Modes
    2. 2.2 Output Voltage Ripple
    3. 2.3 Load Transients
    4. 2.4 Start-Up Sequence
  7. 3Testing and Results
    1. 3.1 Efficiency Graphs
    2. 3.2 Efficiency Data
    3. 3.3 No Load and OFF State Power Consumption
    4. 3.4 Thermal Images
    5. 3.5 Bode Plots
    6. 3.6 Load Regulation

3.4 Thermal Images

Thermal images are shown in the following figures. All images were captured with the unit under test (UUT) enclosed in a 30-cm × 45-cm × 20-cm Plexiglas box at 25ºC ambient, after a 30-minute warm up. For the full load images, the unit was tested with 390-VDC input, 3.7-A load on 12VSB and no load on P18V and S12V. Forced air was used, with the fan current limited to 200 mA. Table 3-8 summarizes the results of the full load images. In the OFF state image, the unit was tested with a 310-VDC input and DIS shorted to PGND. No forced air flow was used. The maximum temperature was 65.3°C, measured on the depletion mode start-up or sensing FET Q2.

Table 3-8 Full Load Thermal Summary
Reference Designator Description Maximum Temperature (°C)
U1 LMG2610 GaN half-bridge 52.1
U3 UCC28782 ACF controller 48.5
N/A Planar transformer PCB near core on primary side 53.0
CORE50 Planar transformer core 49.5
N/A Planar transformer PCB near core on secondary side 51.7
Q50 Synchronous rectifier FET 52.4
U50 UCC24612 SR driver 57.6
R3 Secondary current sense resistor 48.8
GUID-20230104-SS0I-9RLH-HZ4R-J342NBHGLPFM-low.jpg Figure 3-4 Thermal Image Full Load (GaN-Side of Assembly)
GUID-20230104-SS0I-DC4D-DVWS-C9R4VXXH9HHD-low.jpg Figure 3-5 Thermal Image Full Load (Transformer-Side of Assembly)
GUID-20230104-SS0I-N5KJ-QHMG-NFSZGCPQPHB5-low.jpg Figure 3-6 Thermal Image OFF State(GaN-Side of Assembly)