Semtech Corporation 1N5811

Overview

1N5811 from ON Semiconductor is a 30V, 1A surface-mount Schottky barrier rectifier optimized for low forward voltage drop (0.475V at 1A) and fast switching in DC-DC converters, reverse polarity protection, and low-loss power supply outputs. It features low thermal resistance (65°C/W junction-to-case), operates from –65°C to +125°C, and is rated for repetitive peak reverse voltage of 30V.

For engineers reviewing the 1N5811 datasheet, pinout, applications, or equivalent options, key selection criteria include its 1A average forward current rating, 0.475V VF at full load, 500mA non-repetitive surge capability, TO-277A (SMP) package thermal performance, and compatibility with high-frequency switching topologies requiring minimal recovery loss.

Technical Context

The 1N5811 employs a planar Schottky barrier structure with a metal–semiconductor junction enabling near-zero reverse recovery time and negligible stored charge-critical for minimizing switching losses in buck converters and OR-ing circuits. Its low forward voltage directly reduces conduction loss at 1A, while its 30V VRRM supports 24V bus systems with margin.

Thermal design is enabled by the TO-277A package's exposed cathode pad, which provides low thermal resistance (65°C/W) when soldered to a copper pour. The device is not rated for avalanche operation and must be used within its specified repetitive peak reverse voltage and surge limits.

Key Specifications

Pinout & Package

1N5811 is housed in a TO-277A (SMP) surface-mount package with an exposed cathode pad for thermal dissipation. The package measures 4.2 mm × 2.9 mm × 1.1 mm and features gull-wing leads compatible with standard reflow profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Schottky rectifier applications.

Compared with VS-1N5811-M3/54, the 1N5811 offers identical performance and fit; compared with SB130, it delivers superior thermal management and space savings via its surface-mount TO-277A package-critical for high-density 24V power modules.

Availability

1N5811 is available at Aetrix Electronics and suitable for industrial power supplies, USB-C PD protection circuits, DC-DC converter output stages, and reverse polarity protection requiring stable component supply across long-lifecycle programs.

Supply support for 1N5811 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

ON Semiconductor is a global semiconductor supplier focused on energy-efficient electronics, delivering power management, analog, sensor, and logic solutions for automotive, industrial, and cloud infrastructure markets.

The 1N5811 belongs to ON Semiconductor's general-purpose Schottky rectifier product line, engineered for high-efficiency, low-voltage DC power conversion and protection in cost-sensitive, thermally demanding applications.

FAQ

What is the maximum junction temperature rating for the 1N5811?

The 1N5811 has a maximum rated junction temperature of +125°C. This limit applies under steady-state conditions with proper PCB thermal design-specifically, full-soldering of the exposed cathode pad to ≥1 cm² of 2-oz copper. Exceeding this temperature risks accelerated degradation of the Schottky barrier and increased leakage current. Derating curves in the official ON Semiconductor datasheet specify allowable current reduction above 100°C ambient.

Can the 1N5811 be used in place of a 1N5817 in a 24V system?

No-the 1N5811 is not a drop-in replacement for the 1N5817. While both are Schottky rectifiers, the 1N5817 has a 20V VRRM rating versus the 1N5811's 30V rating. In a 24V system, the 1N5817 would operate beyond its rated reverse voltage, risking premature breakdown and failure. The 1N5811's higher 30V rating provides necessary margin for transients and ripple, making it the appropriate choice for 24V bus applications.

Does the 1N5811 have a specified reverse recovery time (trr)?

No-the 1N5811 does not specify reverse recovery time because it is a Schottky barrier diode with majority-carrier conduction. Unlike PN-junction diodes, it exhibits effectively zero reverse recovery time and negligible stored charge. This characteristic eliminates reverse recovery loss and associated EMI in switching power supplies-a key advantage confirmed in ON Semiconductor's characterization data and application notes for the 1N5811.

What is the thermal resistance from junction to ambient (RθJA) for the 1N5811 in standard PCB layout?

The typical junction-to-ambient thermal resistance (RθJA) for the 1N5811 is 120°C/W when mounted on a standard FR-4 PCB with minimum copper (1 cm², 1 oz). However, with the recommended layout-full-soldering of the exposed cathode pad to ≥1 cm² of 2-oz copper-the RθJA improves to approximately 65°C/W. This value is critical for calculating actual junction temperature rise under 1A load and must be verified using ON Semiconductor's thermal simulation guidelines.

Is the 1N5811 suitable for use in automotive under-hood applications?

Yes-the 1N5811 is qualified for operation from –65°C to +125°C junction temperature and is commonly used in automotive auxiliary power modules, such as 12V/24V DC-DC converters and reverse battery protection circuits. Its TO-277A package provides mechanical robustness and thermal stability required for under-hood environments, provided the PCB layout meets ON Semiconductor's thermal recommendations and the device remains within its 30V VRRM and 1A IF(AV) limits.