Share: Problems with using LM25119

qwqwqw2088

Share: Problems with using LM25119 [Copy link]

Question 1: LM25119 application problem As shown in the attached schematic diagram, I used LM25119 to make a power supply with an output of 12V & 30A. The UVLO pin of the main chip uses a transistor to control the on/off of the chip. The current shutdown signal and UVLO situation are shown in the attached Figure 2. A 0.7V signal is added to the base of the transistor, and the UVLO pin can be pulled down to 0V for 300ms. The problem now is that this 300ms time cannot turn off the output of LM25119. May I ask, when UVLO is pulled low, how long does it take for LM25119 to turn off the output? Is there any way to adjust this delay time, or other ways to control the output of lm25119? Thank you! TI expert answers: If VCCDIS > 1.25 V, the internal VCC regulators are disabled. The drive voltage is turned off, the MOS does not start, and the output is naturally turned off. If this is inconvenient, try to reduce the SS pin capacitance based on your existing circuit, for example, within 1nF. If it still does not meet the requirements, continue to reduce it until it is directly suspended. However, you need to evaluate whether there is a problem with the lack of soft start and excessive surge current. >>More Questions and Answers Question 2: About the uneven current in the two paths of LM25119Input 24V, output 12V, load 30A, frequency 400KHZ, the current in the two paths is uneven, is there anyone who can solve it? Please let me know! ! ! ! ! These are the current waveforms of the two paths Is there any expert who can analyze it? ? ? ? ? Where to start? This chip does not seem to have an adjustment for the current sharing coefficient? Can you explain it in detail? Thank you! >>More Questions and Answers