Troubleshooting AC Input Voltage Variations in UCC28056EVM-296 and UCC25630-1EVM-291

Addressing issues with input voltage fluctuations in UCC28056EVM-296 and UCC25630-1EVM-291, where the voltage slowly decreases under different load conditions. Problems include output stopping at varying AC voltages based on load and hunching behavior at different load levels. Countermeasures are needed to stabilize the input voltage without adding new parts. Detailed waveform analysis and images provided.

• Troubleshooting
• Voltage Fluctuations
• UCC28056EVM
• UCC25630-1EVM
• Load Conditions

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Uploaded on Sep 20, 2024 | 0 Views

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1. UCC28056EVM-296 + UCC25630-1EVM-291 ( IC is changed to UCC256304 ) Problems at Input voltage slowly down. Countermeasure required with no parts addition.

2. <Problem 1. > AC Input voltage very slowly down. The AC voltage when the output stops depends on the load value. Output stops at AC78V (load 10A), AC43V (load 5A), AC23V(load 1A) Why? Countermeasure is . <Problem 2.> AC Input voltage very slowly down. Output Hunching at 10A load. Waveform No.4 Not Hunching at 1A load (Waveform No.3) and 5A load (Waveform No.5) Why? Countermeasure is .

3. Blue PFC OUT 100V/div Red LLC TP9 5V/div Green LLC TP6 2V/div Pink LLC OUT 5V/div No1. Input voltage very slowly up at 120W load

4. Blue PFC OUT 100V/div Red LLC TP9 5V/div Green LLC TP6 2V/div Pink LLC OUT 5V/div No2. Input voltage very slowly up at no load

5. Blue PFC OUT 100V/div Red LLC TP9 5V/div Green LLC TP6 2V/div Pink LLC OUT 5V/div No3. Input voltage very slowly down At 1A load Output stops at AC23V

6. Blue PFC OUT 100V/div Red LLC TP9 5V/div Green LLC TP6 2V/div Pink LLC OUT 5V/div No 4. Input voltage very slowly down At 10A load Output stops at AC78V

7. Blue PFC OUT 100V/div Red LLC TP9 5V/div Green LLC TP6 2V/div Pink LLC OUT 5V/div No 5. Input voltage very slowly down At 5A load Output stops at AC43V