LM2931T-5.0 LM2931T-5.0/NOPB LM2931T-5.0G LM2931T-50 LM2931T-5V LM2931Z LM2931Z-3.3 LM2931Z-5 LM2931Z-5.0 LM2931Z-5.0 稳压(齐纳)二极管