What the clamping and breakdown specs mean for your rail
The SMAJ20CA-13: Its 20V reverse standoff voltage means it sits across a 20V nominal rail without conducting leakage; the breakdown range starts at 22.2V minimum, so the device begins to avalanche before the rail exceeds about 22V. The single-channel construction protects one line per device.
Obsolete — what that means for procurement
Diodes Incorporated lists the SMAJ20CA-13 as Obsolete. No official successor order code is recorded.
Housed in the DO-214AC (SMA) surface-mount package, with the supplier device package also designated SMA. The footprint is standard for this JEDEC outline — the cathode band (or bidirectional marking) orients the part on the pad.