12V rail ESD clamp in a SOD-523 footprint
The ESD5Z12T5G is a unidirectional Zener-type ESD suppressor from onsemi, designed to clamp transients on signal lines with a 12V reverse standoff voltage. Its 240W peak pulse power rating means it can absorb the energy from an ESD strike or a short cable discharge without failing — useful on I/O ports and connector pins where the board has limited space. The 55pF capacitance at 1MHz is low enough to avoid loading high-speed interfaces like USB 2.0 or 100BASE-TX, where added capacitance would round the edges and close the eye diagram. The SOD-523 package is a 1.6 mm × 0.8 mm body — it fits under a connector shroud or alongside a series resistor without crowding the adjacent passives.
Breakdown starts at 14.1V minimum, giving a 2.1V guard band above the 12V rail — enough to keep the part out of conduction during normal operation while still reacting before the downstream IC's absolute maximum is hit. The clamping voltage is 25V at the peak pulse current of 9.6A (8/20µs waveform), which is the voltage the protected IC sees across its pins during the event.
onsemi lists the ESD5Z12T5G as Active, so there is no last-time-buy deadline or end-of-life notice to track. For volume pricing or a firm lead time, submit an RFQ against your BOM quantity — we source through authorized channels and confirm availability at quote time.
Where it fits on the board
Surface-mount to SOD-523 — the footprint is a two-pad layout with the cathode marked by a bar on the body. No power-line protection — this is a signal-line clamp, not a mains transient suppressor.