Breakdown and clamping — the two numbers that define the protection threshold
This 1N6121AUS is a Zener-type transient-voltage-suppression (TVS) diode from Microchip, designed to clamp overvoltage transients on a 32.7 V nominal rail. The breakdown voltage (Vbr) is guaranteed at a minimum of 40.9 V, meaning the device starts conducting avalanche current when the line exceeds that threshold. The clamping voltage (Vc) is held to a maximum of 59.1 V at the peak pulse current of 8.5 A under the 10/1000 µs waveform — this is the voltage the protected circuitry must survive without damage. The SQ-MELF B package is a hermetic, surface-mount ceramic body — common in high-reliability and military/aerospace designs where moisture sensitivity and long-term field life are critical.
The hermetic MELF package also resists moisture ingress better than molded plastic SMDs, which matters for conformal-coated assemblies or high-humidity environments.
For volume BOM commitments, we source against the RFQ quantity through our multi-supplier network — no stock-holding claim, but the active status means lead times are predictable. The SQ-MELF package is a standard Microchip offering, so alternate date-code lots are traceable through the authorized chain.