LM3940D-3.3 LM3940D-5.0 LM3940IMP LM3940IMP-1.8 LM3940IMP-2.5 LM3940IMP3.3 LM3940IMP-3.3 LM3940IMP-3.3 TEL:88834448 LM3940IMP-3.3 电源IC LM3940IMP-3.3/5.0V