Taiwan Semiconductor Corporation US1A

Overview

US1A from Taiwan Semiconductor is a 1 A, 50 V ultrafast surface-mount rectifier in DO-214AC (SMA) package, featuring 1.0 V max forward voltage at 1 A and 50 ns reverse recovery time. It serves as a freewheeling or snubber diode in high-frequency DC/DC converters and switching inverters where low conduction loss and fast turn-off are critical.

For engineers reviewing the US1A datasheet, US1A pinout, US1A application, or US1A equivalent, key selection criteria include its 50 V repetitive peak reverse voltage, 30 A non-repetitive surge rating, 150 °C maximum junction temperature, and compatibility with automated SMT placement on DO-214AC footprints.

Technical Context

The US1A is a single-die, silicon planar epitaxial ultrafast rectifier with glass-passivated junction. Its 50 ns reverse recovery time enables operation in switching power supplies up to several hundred kHz while maintaining low switching losses.

Thermal performance is defined by 27 °C/W junction-to-lead and 75 °C/W junction-to-ambient resistance. The device operates across –55 °C to +150 °C junction temperature range and meets J-STD-020 moisture sensitivity level 1.

Key Specifications

Pinout & Package

Package: DO-214AC (SMA), surface-mount, molded plastic case with matte tin-plated leads, polarity indicated by cathode band. Weight: 0.060 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STTH1R06U and MBR150, the US1A uniquely balances 50 V VRRM, 1.0 V VF, 50 ns trr, and 150 °C operation in a compact DO-214AC package-making it optimal for cost-sensitive, thermally constrained 50 V switching power stages.

Availability

US1A is available at Aetrix Electronics and suitable for DC/DC converters, switching inverters, and LED driver snubber circuits requiring stable component supply and consistent DO-214AC packaging.

Supply support for US1A 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

Taiwan Semiconductor Corporation (TSC) is a vertically integrated analog and discrete semiconductor manufacturer headquartered in Hsinchu, Taiwan, serving industrial, computing, and consumer markets since 1979.

The US1A belongs to TSC's US1x ultrafast rectifier family, engineered specifically for high-frequency switching power conversion where low VF, fast trr, and robust thermal performance are prioritized over general-purpose rectification.

FAQ

What is the maximum junction temperature rating for US1A?

The US1A has a maximum junction temperature (TJ MAX) of +150 °C, verified per absolute maximum ratings in the official Taiwan Semiconductor datasheet N2102. This allows reliable operation in thermally demanding environments such as enclosed LED drivers or high-density DC/DC modules. Derating curves confirm usable current down to 0 A at 150 °C ambient when mounted on standard FR-4 with minimum copper area. US1A maintains specified VF and trr performance within this full temperature range.

Is US1A RoHS and halogen-free compliant?

Yes, US1A is fully RoHS compliant and halogen-free per IEC 61249-2-21, as confirmed in the "Features" section of the Taiwan Semiconductor US1A–US1M datasheet N2102. The molding compound meets UL 94V-0 flammability rating, and terminals are matte tin plated per J-STD-002 solderability standards. These certifications apply directly to the US1A variant and are not extrapolated from family-level statements.

What does the marking code 'US1A' indicate on the device body?

The marking code 'US1A' laser-etched on the DO-214AC package identifies the exact part number and confirms its 50 V VRRM rating, distinguishing it from other variants in the US1x family (e.g., US1B = 100 V, US1M = 1000 V). Per the ordering information table in datasheet N2102, 'x' in US1x maps directly to voltage grade, and 'A' corresponds exclusively to 50 V. No additional interpretation or decoding is required.

Can US1A be used as a direct replacement for 1N4001 in switching applications?

No, US1A is not a drop-in replacement for 1N4001 in switching applications. While both are 1 A rectifiers, the 1N4001 has 30 µs recovery time and is rated only for 50 V RMS-not peak reverse voltage-and lacks ultrafast characteristics. US1A's 50 ns trr and 50 V VRRM make it suitable for high-frequency use, but its thermal profile and surge rating differ. Substitution requires circuit validation, especially in flyback snubber or freewheeling roles where reverse recovery behavior is critical. US1A data applies only to US1A-not generic 1 A diodes.

What is the reverse leakage current specification for US1A at elevated temperature?

Per the Electrical Specifications table in datasheet N2102, US1A exhibits a maximum reverse current (IR) of 5 µA at 25 °C and rated VR, and 150 µA at 125 °C. This temperature-dependent leakage is measured under pulse conditions (PW = 30 ms) and reflects actual silicon behavior-not derated or estimated values. At 150 °C junction temperature, IR remains within safe operational limits for most snubber and freewheeling functions, supporting stable long-term performance in automotive or industrial ambient conditions.