TIDT256A March   2022  – March 2022

 

  1.   Description
  2.   Features
  3.   Applications
  4. 1Test Prerequisites
    1. 1.1 LM5156-Q1
      1. 1.1.1 Loading LM5156-Q1
      2. 1.1.2 LM5156-Q1 SEPIC Bode Loop Testing
    2. 1.2 Loading UCC14240-Q1
    3. 1.3 UCC5870-Q1 and UCC5870-Q1 EVM GUI
    4. 1.4 Voltage and Current Requirements
    5. 1.5 Required Equipment
    6. 1.6 Considerations
    7. 1.7 Dimensions
  5. 2Testing and Results
    1. 2.1 SEPIC Efficiency Graphs
    2. 2.2 SEPIC Efficiency Data
    3. 2.3 SEPIC Bode Plots
    4. 2.4 Thermal Images
  6. 3Waveforms
    1. 3.1 SEPIC Switching
    2. 3.2 SEPIC Output Voltage Ripple
    3. 3.3 SEPIC Load Transients
    4. 3.4 SEPIC Start-Up Sequence
    5. 3.5 Isolated Bias Supply Start Up and Shutdown
    6. 3.6 Isolated Gate Drive

3.5 Isolated Bias Supply Start Up and Shutdown

Isolated bias supply start-up and shutdown waveforms are shown in this section. The focus of these tests was on proper ramp up and ramp down of outputs with abrupt and noisy loading and with a noisy and bouncing enable signal.

GUID-20220322-SS0I-WVKW-4SCM-5GMCXBFFGMLR-low.jpg
24 VDC into isolated DC/DC:
75-mA load between +15-V and –5-V output
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output with 0.5-V overshoot
Scope channel 3 (blue) is the enable signal
Scope channel 4 (green) is the –5-V output.
Figure 3-13 Isolated DC/DC Turn On by Rising Enable Signal
GUID-20220322-SS0I-ZGKW-P5XT-TGXGTGCSTQTD-low.jpg
24 VDC into isolated DC/DC:
75-mA load between +15-V and –5-V output
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output with 0.5-V overshoot
Scope channel 3 (blue) is the enable signal
Scope channel 4 (green) is the –5-V output
Figure 3-15 Isolated DC/DC Turn On by Rising Enable Signal With Switch Bounce
GUID-20220322-SS0I-97NB-VHWS-KBPSLL98KMKN-low.jpg
24 VDC into isolated DC/DC:
75-mA load between +15-V and –5-V output
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output
Scope channel 3 (blue) is the enable signal
Scope channel 4 (green) is the –5-V output.
Figure 3-14 Isolated DC/DC Turn Off by Falling Enable Signal
GUID-20220322-SS0I-FHVZ-MXDF-74B2XVW62FMK-low.jpg
24 VDC ramped up into isolated DC/DC:
75-mA load between +15-V and –5-V output. Enable is always high.
Scope channel 1 (yellow) is load current off DC/DC (noisy)
Scope channel 2 (red) is the +15-V output with 0.5-V overshoot
Scope channel 3 (blue) is ramping up main VIN
Scope channel 4 (green) is the –5-V output.
Figure 3-16 Isolated DC/DC Turn On by Rising Main VIN to 24 V