LM2990SX LM2990SX-12 LM2990SX-12/NOPB LM2990SX-15 LM2990SX-15 其他被动元件 LM2990SX-15/NOPB LM2990SX-15-NS LM2990SX-5 LM2990SX-5.0 LM2990SX-5.0/NOPB