5.1V Zener diode 0.5W Zener diode 5.1 V 1/2W

Here we have a 5.1v 0.5w (watt) zener diode. If you are unfamiliar with diodes, they typically only allow current to flow in one direction. Of course, there are many different kinds and styles of diodes out there. The zener diode is special because it allows current to flow backwards or in reverse at a specific voltage and up to a certain amount. This particular zener diode will allow current to flow in the opposite direction that the diode normally freely allows current to flow when the reverse current reaches 5.1v (volts). The zener diode can reliably operate in this reverse state whereas other diodes are not typically meant to. Some textbook uses for them would be in waveform clippers, voltage shifters, and voltage regulators. Again, there is a myriad of other uses for the 5.1v 0.5w zener diode.

5.1 Volt Zener Diode, 500mW, 5% tolerance. Low noise high stability, suitable for voltage regulation or voltage dropping in low current circuitry.

DO-35 package, For more information please see the Vishay?BZX55 Data Sheet