Schottky rectifier — 40 V, 3 A, hermetic barrel
The 1N5822US is a 40 V, 3 A Schottky rectifier in a hermetic SQ-MELF (B) package from Microchip Technology. Its 500 mV forward drop at 3 A keeps conduction losses low in power rectification, freewheeling, and OR-ing stages. The junction temperature range spans -65 to 125 °C — a military-grade temperature window that suits avionics power supplies, downhole instrumentation, or outdoor telecom rectifier stages where commercial parts would derate or fail.
Switching speed and leakage — what the ratings mean
Listed with a fast recovery spec of < 500 ns at > 200 mA — unusual for a Schottky, which is already a majority-carrier device. This suggests the part is characterized for higher-frequency rectification (e.g., 100 kHz+ switching supplies) where stored charge in a standard Schottky could still cause ringing. Reverse leakage is 100 µA at the full 40 V rating. Leakage in a Schottky doubles roughly every 10 °C; at 125 °C junction, expect leakage in the milliampere range — factor that into standby power budgets for hot environments.
SQ-MELF (B) is a hermetic ceramic barrel with metallized end caps — no plastic body, no moisture sensitivity. It survives high-humidity or vacuum environments where a standard SMC package would absorb moisture and pop during reflow. Surface-mount, but the barrel shape requires careful solder-paste stencil design: the end-cap terminations need enough paste volume to form a fillet without bridging to the body. The package footprint is non-standard — confirm the land pattern against the manufacturer's recommended pad layout before committing the PCB.
Lifecycle and compliance
RoHS non-compliant. The hermetic construction typically uses lead-bearing solder in the end-cap termination. For EU or RoHS-enforced builds, an exemption (e.g., RoHS Annex III exemption 7a for high-melting-temperature solder) may be required — verify with your compliance team before specifying.