Part of the Day · SS34 — SMB 3A 40V Schottky diode

Part of the Day · 2026-10-23

A 3A Schottky diode in an SMB package, often used for freewheeling in DC-DC converters and reverse-polarity protection. Its forward voltage is a low 0.50V at 3A.

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 (SMB · top view · approx. 20×)

Pins The end with the band (or notch) is the cathode (−)

Package SMB

Key specifications

Values are from the Won-Top Electronics (WTE) datasheet.

Marking and pins

Typical uses

• Freewheeling diode in DC-DC buck converters
• Reverse-polarity protection on power inputs — low voltage drop
• Reverse-current blocking for solar panels and batteries

Companion & similar parts

• SS36 — 60V type from the same datasheet — higher forward voltage, max 0.75V
• SS32 — 20V type of the same family — do not use in a 40V position
• SS310 — 100V type of the same family, forward voltage max 0.85V

The body is marked with the part number SS34 as is. Schottky reverse current rises sharply with temperature (0.5mA at 25℃ → 20mA at 100℃), so allow margin in high-temperature, high-voltage positions.