The STMicroelectronics 1.5KE7V5CARL is a 1500W bidirectional Zener TVS diode from the 1.5KE TRANSIL series, packaged in a through-hole DO-201AA / DO-27 axial case. It is designed for general-purpose transient overvoltage protection on DC power rails, low-frequency signal lines, and AC secondary-side circuits where a single device must clamp both polarities. The bidirectional configuration (one channel) means it replaces two back-to-back unidirectional TVS diodes, saving board space and BOM lines on bipolar supplies or AC-coupled lines. The key protection numbers: reverse standoff voltage of 6.4V (the maximum DC voltage the protected line can carry without the diode conducting), minimum breakdown voltage of 7.13V (where clamping begins), and a maximum clamping voltage of 14.5V at the peak pulse current of 690A for an 8/20µs waveform. The 1500W peak pulse power rating (10/1000µs waveform) is the headline surge capability — it tells you this part handles a 1.5kW transient for a millisecond-class event, typical for lightning-induced surges or inductive load dumps in industrial and telecom gear. One spec that limits application scope: capacitance of 4250pF at 1MHz. That is high compared to modern low-capacitance TVS diodes (which run 1–10pF). This part is not suitable for protecting high-speed data lines (Ethernet, USB, CAN-FD) — the capacitive loading would distort signal edges. It belongs on power inputs, relay coils, solenoid drivers, or DC bus rails where signal integrity is not the concern.
Obsolete — sourcing reality and the replacement question
STMicroelectronics no longer manufactures this exact order code. The closest functional sibling in the same family is the 1.5KE7V5A — the unidirectional version of the same 1500W, 6.4V standoff, 7.13V breakdown, 14.5V clamp ratings. The difference is the number of bidirectional channels: the 1.5KE7V5CARL is a single bidirectional device; the 1.5KE7V5A is unidirectional and requires two devices (back-to-back) to achieve bidirectional protection. No official ST successor order code is listed for the 1.5KE7V5CARL, so the replacement path is either the unidirectional sibling with a layout change, or a functionally equivalent bidirectional TVS from another manufacturer at the same 6.4V standoff / 1500W rating class.