LM25143: sch. review

Hi Eric,

Please complete and send the LM25143 quickstart calculator as it is useful for component selection, loop design, power loss analysis, etc.

Regards,

Tim

Here are some comments on the schematic:

1. VCC caps should be 2 x 2.2uF (not 0.1uF).
2. Add local VIN cap (e.g. 10-100nF) at the VIN pin of the controller.
3. No need for low-side gate resistor.
4. Use only one inductor, not two in parallel.
5. Consider adding RC filter at CS and VOUT to mitigate any current sense noise.
6. RC snubber resistor should be tied to GND, cap goes to SW (better for heatsinking the resistor). A snubber shouldn't be required with good layout (see EVM).
7. Consider adding more ceramic output cap to conduct the AC ripple current.
8. Tie VCCX to GND if not used.
9. COMP cap at 220pF seems way too low - check the quickstart calculator.
10. DITH cap should be 10nF for ideal 8-10kHz modulating frequency. 0.1uF is too high.
11. RES cap could be higher, e.g. 470nF.
12. VDDA cap should be 470nF too.

Regards,

Tim