The DO-201AD axial package is a through-hole legacy footprint, common in industrial power supplies, telecom line cards, and motor drive snubber circuits where board space isn't the constraint.
Voltage ratings that define the protection window
The breakdown voltage (minimum 15.2V) sits between the 13.6V standoff and the 22.5V clamp — that 2.6V margin is the avalanche region where the diode absorbs the surge. For a 12V nominal rail with 10% tolerance (13.2V max), the 13.6V standoff leaves only 0.4V headroom; a 12V rail at 5% tolerance (12.6V) is safer. The 1500W peak pulse rating at 1ms means the diode can handle a 66.7A surge at the clamp voltage — enough for most secondary-side transients in a 100W-class supply.
Lifecycle reality — obsolete, not gone
onsemi lists the 1N6276A as Obsolete. For sustainment programs — medical, defence, industrial control — this means the only sourcing path is the open market or a last-time buy from remaining distributor stock.
Temperature range and mounting note
The through-hole axial body (DO-201AD) requires a 1.0mm to 1.3mm diameter hole on the PCB — the lead diameter is typically 0.96mm. No moisture sensitivity level applies to hermetic glass-passivated Zener diodes; no bake-out is needed before soldering.