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LT8705A cannot work normally

hello

our product SPEC: input voltage :10V-60V, output: 14.6V/10A,  we use LT8705 to design circuit.

Now we test this power supply.  and set the input voltage is 12V, and output current from 1A to 5A。

when the output current is 3A,  output voltage is below 14V; we measurement the waveform on pin of SW2, find that there are abnormal DIP waveform which should be high.

which items do we need to check that can fix this issue?

Thanks a lot!

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  • Hi JesseLee,

    Four-switch buck-boost is not an easy design especially at 146W. We would always recommend to start with our demo board as working reference design because PCB layout can be a big factor to making converter work properly. Please also verify your design in LTspice. 

    For further support, please connect to local ADI FAE. If you can provide project details, customer, estimate annual usage, I can help connect you to one. Another way is to post question to technical support through this channel: form.analog.com/.../techsupport.aspx

  • To investigate a layout issue, compare your layout with the DC2596A layout. Erratic switching duty cycle often indicates a layout issue. It is possible that converter is toggling between buck-boost mode and boost mode causing a changing SW2 duty cycle