Part of the Day · 1N5819 — DO-41 1A 40V Schottky diode

Part of the Day · 2026-10-24

A leaded 1A Schottky diode in a DO-41 package, widely used for reverse-polarity protection and freewheeling in low-voltage power supplies. Its forward voltage is max 0.60V at 1A, so it loses less than an ordinary rectifier diode (1N4007: max 1.1V).

Actual size

↓ Actual size, left edge aligned to 0 on the ruler

One ruler tick = 1mm. On PC this is actual size on a 24-inch FHD monitor at 100% zoom; on iPhone it adjusts automatically. For other screens, use “Calibrate ruler” below.

Enlarged (DO-41 · top view · approx. 13×)

Pins The banded end is the cathode (−)

leads partly shown · Package DO-41

Key specifications

Values are from the Diodes Incorporated datasheet.

Marking and pins

Typical uses

• Reverse-polarity protection on power inputs — the low voltage drop suits 5V and 3.3V circuits
• Freewheeling diode in small DC-DC converters and inverters
• Reverse-current blocking for batteries and solar panels, OR-ing diode to combine two supplies

Companion & similar parts

• 1N5817 — 20V type from the same datasheet — lower forward voltage (max 0.450V at 1A) but lower voltage rating
• 1N5818 — 30V type from the same datasheet — max 0.550V at 1A
• 1N4007 — Same DO-41 1A size but a 1000V standard-recovery type — for high-voltage rectification, with higher forward voltage and slower

The body is marked 1N5819 plus a date code (YWW — 2-digit year and week). Schottky reverse current rises sharply with temperature (1.0mA at 25℃ → 10mA at 100℃) and the maximum temperature is only 125℃, so allow margin in hot positions. The 1.0A average current is rated at a lead temperature of 90℃, measured 9.5mm from the body.