The AU3321D5 is a SOD-523 RoHS-compliant transient voltage suppressor (TVS) manufactured by Applied Power. It has reverse standoff voltage protection of 10V, 3.5V, and 3.3V, and is designed specifically to protect circuit boards from electrostatic discharge and other transient voltage threats. It is rated for current up to 250mA, and has a peak pulse power rating of 600W. It is available in SOD-523, SMA, and SOT-23 packages. Its size, low cost, and reversibility make it an ideal choice for a wide range of electronic component designs.