400 W Zener TVS in DO-214AC
The SMAJ170A-13-F: Its 170 V reverse standoff voltage and 189 V minimum breakdown voltage place it on 170 V DC rails or 120 VAC rectified lines where the nominal bus sits below the standoff and the TVS stays out of conduction until a transient pushes past the breakdown threshold.
Clamping and current capability
This means a transient that drives the full 1.4 A through the device will be clamped to 275 V, protecting downstream components rated above that level. The 400 W peak pulse power rating is the product of the clamping voltage and the peak current at that test condition — a standard industry metric for comparing TVS devices across the same waveform. The 400 W rating is derated at elevated temperatures per the datasheet curve; at 150°C the peak pulse power drops to roughly 60% of the 25°C rating, so a hot-running board needs to budget the derated capability.
Package and board fit
Housed in the DO-214AC (SMA) package, the SMAJ170A-13-F is a surface-mount device with a low-profile body suited for dense PCB layouts. The SMA footprint is shared across the SMAJ series, so a common land pattern serves the full voltage range from 5 V to 188 V. The unidirectional design uses a single Zener junction in the avalanche breakdown region. The cathode band on the package identifies the anode-to-ground orientation; reverse the polarity and the device conducts like a forward-biased diode at roughly 0.7 V, which will not protect the circuit. The power line protection flag is marked 'No', meaning this device is intended for signal or DC bus protection, not for AC mains clamping.
Sourcing and compliance
The base product number is SMAJ170, with the -13-F suffix denoting the Tape & Reel packaging option. Compliance documentation (RoHS, REACH) is provided by Diodes Incorporated per standard industry practice for active catalog parts.