Bidirectional Zener clamp, 1500 W peak pulse
The 1.5KE150C-B: The bidirectional configuration means a single device protects both polarities — useful on AC signal lines or DC rails where the polarity could reverse during a fault. It is not a power-line protector (the spec explicitly flags no power line protection), so keep it on signal or low-power DC bus applications.
DO-201 axial, through-hole, -55 to 175 °C
Housed in a DO-201AA (DO-27) axial-lead package, the 1.5KE150C-B is a through-hole part — the leads are formed for through-hole insertion, not surface mount. The operating junction temperature range spans -55 °C to 175 °C, covering industrial and most automotive under-hood ambient conditions without derating at the high end. The DO-201 body is large enough to read the marking without magnification — helpful for field-service verification when you are swapping it on a board without a schematic in hand. Polarity is obvious on a bidirectional part: no band to misinterpret.
Obsolete — sourced through independent channels
Littelfuse lists the 1.5KE150C-B as obsolete. There is no pin-compatible direct replacement from Littelfuse in the same 1.5KE series with identical breakdown and standoff ratings. If you need a drop-in alternative, the closest functional match is another 1500 W bidirectional TVS in DO-201 with a 128 V standoff — but confirm the breakdown window and clamping voltage against your circuit's protection threshold.