Taiwan Semiconductor Corporation 1SMA5931

Overview

1SMA5931 from Taiwan Semiconductor is a 1.5W surface-mount Zener diode with a nominal zener voltage of 18 V, ±5% tolerance, 20.8 Ω dynamic impedance at 12 mA test current, and maximum leakage current of 0.5 µA at 13.7 V reverse bias. It operates within -55°C to +150°C junction temperature range and is used for voltage regulation in DC/DC converters and power supply feedback loops.

For engineers reviewing the 1SMA5931 datasheet, 1SMA5931 pinout, 1SMA5931 application, or 1SMA5931 equivalent, key selection criteria include its DO-214AC (SMA) package compatibility, low-inductance glass-passivated junction, Class 3B HBM ESD rating, and verified 1.5 W steady-state power dissipation at TL = 75°C.

Technical Context

The 1SMA5931 functions as a single-die, unidirectional voltage reference device with tightly controlled zener breakdown characteristics. Its 18 V nominal regulation point is guaranteed at thermal equilibrium with IZT = 12 mA, and it maintains stable performance under transient load conditions due to low dynamic impedance (20.8 Ω) and minimal capacitance.

Designed for surface-mount assembly on standard PCBs, the device features matte tin-plated leads compliant with J-STD-002 solderability, meets JEDEC JESD201 Class 2 whisker resistance, and carries UL 94V-0 flammability-rated molding compound - all supporting high-reliability industrial power applications.

Key Specifications

Pinout & Package

Package: DO-214AC (SMA), surface-mount, single-anode/single-cathode configuration with cathode indicated by a visible band. Molding compound meets UL 94V-0; terminals are matte tin-plated and solderable per J-STD-002.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1SMA5931, the 1N4746A offers lower power handling and different packaging, while the SMAZ18 matches the DO-214AC form factor but trades 20.8 Ω impedance for broader process tolerance - making 1SMA5931 optimal for precision feedback loops requiring minimal regulation error.

Availability

1SMA5931 is available at Aetrix Electronics and suitable for switching mode power supplies, on-board DC/DC converters, and lighting applications requiring stable component supply, RoHS compliance, and high-volume tape-and-reel delivery (7,500 units per reel).

Supply support for 1SMA5931 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 semiconductor manufacturer specializing in discrete power devices, analog ICs, and protection components for industrial and consumer markets.

The 1SMA59xx series was developed to deliver high-reliability, surface-mount Zener diodes with enhanced ESD robustness and thermal stability for next-generation compact power conversion systems.

FAQ

What is the zener voltage tolerance for 1SMA5931?

The 1SMA5931 has a nominal zener voltage of 18 V with a guaranteed tolerance of ±5%, meaning the actual measured V_Z falls between 17.1 V and 18.9 V at I_ZT = 12 mA and thermal equilibrium. This tolerance is specified per the device's voltage regulation designation and applies across its full operating temperature range.

Can 1SMA5931 be used in place of 1N4746A?

No - while both regulate at 18 V, the 1SMA5931 uses a DO-214AC (SMA) surface-mount package and delivers 1.5 W power dissipation, whereas the 1N4746A is DO-41 through-hole rated at 1 W. Direct substitution requires PCB redesign and thermal reassessment; 1SMA5931 is not a drop-in replacement for 1N4746A.

What is the maximum DC zener current for 1SMA5931?

The maximum DC zener current (I_ZM) for 1SMA5931 is 83 mA, calculated from P_D = 1.5 W and V_Z = 18 V nominal. This value is confirmed in the Electrical Specifications table and represents the highest continuous reverse current the device can sustain without exceeding its thermal limits.

Does 1SMA5931 meet lead-free soldering standards?

Yes - the 1SMA5931 features matte tin-plated leads compliant with J-STD-002 for solderability and is rated for lead-free reflow profiles. Its DO-214AC package is qualified for standard Pb-free SAC305 processes with peak temperatures up to 260°C, and it carries no lead or halogen content per IEC 61249-2-21.

What is the thermal derating behavior of 1SMA5931 above 75°C?

1SMA5931 derates linearly at 20 mW/°C above TL = 75°C when mounted on a 5 mm × 5 mm copper pad test board. At 100°C lead temperature, its usable power drops to 1.0 W; at 125°C, it falls to 0.5 W. Full derating data is shown in Figure 1 of the official datasheet.