Answers to questions during the use of UCC28220,,,

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Answers to questions during the use of UCC28220,,, [Copy link]

Question 1: Questions about the full-bridge power supply made by ucc28220 A full-bridge power supply made by UCC28220 is connected to a boost inductor in front. When the full bridge is interleaved, the open loop boost is about 100V. The transformer turns ratio is 5:25, and the output adopts bridge rectification. The CS1 and CS2 current detection is realized using the drive signal of UCC28220. UCC28220 uses voltage mode control. When the project is loaded with 200W, the drive is turned off for more than 10 seconds and then restarted with the maximum duty cycle (the output voltage is constantly decreasing at this time), causing the boost part to reach 350V and break through the full-bridge MOS tube and the diode of the absorption circuit. I tried to lift the CS1 and CS2 pins and connect them to the chip ground, but the problem still exists. I have measured other pins and found no abnormalities. I still have no clue after a few days. Could you please tell me what is the cause? TI expert asked: If it is switch control, how is the PWM duty cycle controlled? >>More Questions and Answers Question 2: Why is the UCC28220 PWM output always 0? I am debugging the UCC28220 PWM control IC. The peripherals are connected according to the typical circuit. Now the 8-pin Ctrl terminal inputs a 1V constant voltage, and the 4-pin and 6-pin current detection CS1 and CS2 are not connected. The other peripheral components and pin levels are consistent with the datasheet, but I think the current output should be a PWM square wave with the maximum duty cycle determined by the resistors Rchg and Rdischg connected to the 9-pin and 10-pin, but now OUT1 and OUT2 are always 0. I have been looking for a day and a half but can't find the reason. The levels of other pins are normal, but the output is always 0. Has anyone used this chip? Can you give me some advice? Thank you very much! TI expert answer: UCC28220 is a current feedback loop. The CTRL pin is only the input of the voltage loop. A triangle wave signal must be input to the CS current detection pin to output a PWM wave. www.ti.com.cn/power >>More questions and answers