Other Parts Discussed in Thread: LM5146, LM5145
Dear Expert
Our design input 20V Vdc form the AC to DC adaputor ,and LM25145 incloud in the AC-DC board ,output 12V ,peak 15A . Now customer found that they could not start up normaly .And we check that some nosie input in the SS/TRK pin and FB pin . And we decup the C602 in SS/TRK pin , R614&C610 in FB pin , then the LM25145 could start up nomaly .
Below is the sch , AC-DC output have same power GND with LM25145 input , but customer AGND connected the PGND without a isolation .
Customer will redesign the AGND & PGND ,1.could u give us more suggestion about the PCB & Sch ?
2. The FB pin also have some about 1.4V noise , but if we take the R614&C610 in FB pin off , the noise will disapper, could u suggst a value of R614&C610 ,now is 100Ω& 100pF .
3.Does Vout cap ESR is inportant ? How could we choose a proper ESR output cap ?
4. Does phase margin should be cross the 0 point ?
