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Irregular switching signal

Category: Hardware
Product Number: LTC7810

Hi,

I'm using the LTC7810 to get 12V 8A output. My input voltage is 48V and my operating frequency is 493 kHz, my design is as attached LTpowercad work

I use electronic load to test the design at the output. While the switching signals are periodic when there is no load, if I enter even a small load (6 ohm - 2 A) into the system, the signals cease to be periodic. I use Force Continuos Mode for all loads.

Can you help me figure out what my problem is?

  • If you are not already doing so, I would suggest testing one phase at a time. When you step the load and the issue begins, does the duty cycle first reduce to a minimum (<~100ns or so)? If so, it might be the current sense issue. I would also compare to the Demo Board DC2529A schematic and layout which, component by component, should be similar (for example, sense filter RC, etc.). Always nice to start with a Demo Board, get familiar with testing and operation then slowly modify to meet your requirements.