Toshiba Semiconductor and Storage 1SS321,LF

Overview

1SS321,LF from TOSHIBA is a silicon epitaxial Schottky barrier diode optimized for low-voltage, high-speed switching applications, featuring VF(2) = 0.42 V (typ.) at IF = 10 mA, IR ≤ 500 nA at VR = 10 V, and CT = 3.2 pF (typ.) at 1 MHz. It is AEC-Q101 qualified and housed in the SC-59 (JEDEC TO-236MOD) package, commonly used in automotive signal clamping and portable DC-DC converter freewheeling paths.

For engineers reviewing the 1SS321,LF datasheet, 1SS321,LF pinout, 1SS321,LF application, or 1SS321,LF equivalent, key selection criteria include forward voltage drop under 10–50 mA load, reverse leakage at 10 V bias, junction capacitance for high-frequency switching, thermal limits up to 125°C, and AEC-Q101 qualification status for automotive-grade reliability validation.

Technical Context

The 1SS321,LF employs a planar Schottky barrier structure with epitaxial silicon construction, enabling fast recovery (trr not specified but implied by high-speed switching classification) and low conduction loss. Its low VF and sub-μA IR support efficient operation in battery-sensitive and low-power signal routing circuits.

Designed for surface-mount use in compact layouts, the device operates within −55°C to +125°C storage and junction temperature ranges, with absolute maximum ratings including VR = 10 V, IFM = 150 mA (unit), and P = 150 mW - all consistent with SC-59 thermal dissipation limits.

Key Specifications

Pinout & Package

Package: SC-59 (JEITA), identical to JEDEC TO-236MOD - three-terminal surface-mount plastic package with anode, cathode, and exposed cathode pad (pin 3 serves as cathode terminal and thermal relief).

Key Features

Applications

Equivalent & Alternatives

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

Compared with RBS208M10T3G and BAT54C,215, the 1SS321,LF delivers the lowest verified reverse leakage (500 nA max) and AEC-Q101 qualification in a single-diode SC-59 package - making it optimal for automotive signal integrity and battery-constrained sensor nodes where leakage-induced offset and qualification compliance are design-critical.

Availability

1SS321,LF is available at Aetrix Electronics and suitable for automotive signal clamping, portable DC-DC converter freewheeling, and industrial sensor biasing applications requiring stable component supply, long-term lifecycle visibility, and RoHS-compliant sourcing.

Supply support for 1SS321,LF 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

Toshiba Electronic Devices & Storage Corporation designs and manufactures discrete semiconductors, power devices, and logic ICs with emphasis on automotive, industrial, and consumer reliability standards.

The 1SS321,LF belongs to Toshiba's legacy Schottky diode product line launched in 1987, engineered specifically for low-voltage, high-speed switching in space-constrained and thermally demanding environments.

FAQ

What is the maximum reverse voltage rating for the 1SS321,LF?

The 1SS321,LF has a maximum reverse voltage (VR) rating of 10 V and a peak reverse voltage (VRM) of 12 V. These values define its safe blocking capability in DC and transient conditions. Exceeding 10 V in continuous operation risks increased reverse leakage and potential junction degradation. The 12 V VRM allows brief surge tolerance during ESD or inductive kick events, provided energy remains within SOA limits.

Is the 1SS321,LF suitable for automotive applications?

Yes, the 1SS321,LF is AEC-Q101 qualified, confirming its reliability for automotive use in non-safety-critical systems such as body electronics, infotainment interfaces, and sensor signal conditioning. It meets stress test requirements including high-temperature operating life and temperature cycling. However, it is not intended for safety-critical functions like airbag control or ADAS power stages per Toshiba's Unintended Use disclaimer.

What does the "LF" suffix indicate in 1SS321,LF?

The "LF" suffix in 1SS321,LF denotes lead-free (Pb-free) construction and RoHS compliance, confirmed by Toshiba's environmental documentation. It specifies that the terminal finish is matte tin, the mold compound is halogen-free, and the entire assembly meets EU Directive 2011/65/EU requirements. No functional or electrical differences exist between 1SS321 and 1SS321,LF beyond material composition.

How is thermal performance managed in the 1SS321,LF's SC-59 package?

The 1SS321,LF uses an SC-59 package with an exposed cathode pad (Pin 3) that serves as both electrical terminal and thermal path. For optimal thermal performance, this pad must be soldered to a minimum 10 mm² PCB copper pour with ≥2 thermal vias. Under these conditions, the device sustains its full 150 mW power dissipation while maintaining junction temperature ≤125°C at Ta = 85°C - critical for under-hood automotive deployment.

Does the 1SS321,LF have a specified reverse recovery time (trr)?

No, the 1SS321,LF datasheet does not specify reverse recovery time (trr) because Schottky barrier diodes are majority-carrier devices with inherently fast switching - typically in the sub-nanosecond range. Toshiba characterizes it as a "high-speed switching" diode based on low CT (3.2 pF) and low VF, which together enable effective operation in >100 MHz signal paths without measurable minority-carrier delay. trr is not a rated parameter for this device.