Diodes Incorporated 1SMB5946B-13

Overview

1SMB5946B-13 from Diodes Incorporated is a 3.0W surface-mount power Zener diode with a nominal zener voltage of 75V (±5% tolerance), 5Ω dynamic impedance at 140mA test current, and 2000Ω maximum knee impedance. It features ESD rating >16kV (HBM), RoHS-compliant lead-free finish, and SMB package for high-reliability voltage regulation in DC power rails.

For engineers reviewing the 1SMB5946B-13 datasheet, 1SMB5946B-13 pinout, 1SMB5946B-13 application, or 1SMB5946B-13 equivalent, key selection criteria include zener voltage stability under thermal stress, power derating above +25°C, junction-to-terminal thermal resistance, and compliance with Class 3 ESD requirements in industrial power supplies.

Technical Context

This Zener diode operates in reverse breakdown to maintain stable reference voltage across load variations. Its 75V nominal zener voltage is specified at I_ZT = 140mA, with temperature coefficient optimized for mid-range voltage regulation where drift must remain below ±0.08%/°C.

The device uses copper alloy leadframe with matte tin plating and is qualified to J-STD-020 moisture sensitivity Level 1. Thermal resistance from junction to terminal is 25°C/W, enabling effective heat transfer to PCB copper when mounted per AP02001 pad layout.

Key Specifications

Pinout & Package

Package: SMB (Surface Mount Small Outline), molded plastic case rated UL 94V-0, cathode band marking, 0.096 g weight.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ75A and 1N5365B, the 1SMB5946B-13 uniquely balances continuous 3.0W regulation, SMT manufacturability, and Class 3 ESD robustness-making it optimal for space-constrained industrial controllers needing stable DC reference under thermal and ESD stress.

Availability

1SMB5946B-13 is available at Aetrix Electronics and suitable for industrial power supply protection, automotive body control modules, telecom line card surge suppression, and programmable logic controller input conditioning requiring stable component supply and full RoHS compliance.

Supply support for 1SMB5946B-13 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design and manufacturing operations across Asia and the Americas.

The 1SMB59xxB series belongs to Diodes' high-power Zener diode product line, engineered specifically for precision voltage regulation and overvoltage protection in compact SMT power systems operating from -65°C to +150°C.

FAQ

What is the maximum continuous power dissipation for 1SMB5946B-13 at +75°C?

The 1SMB5946B-13 is rated for 3.0W continuous power dissipation at lead temperature (T_L) = +75°C. Above this temperature, it derates linearly at 40 mW/°C. This rating assumes mounting on FR-4 PCB using Diodes Inc.'s AP02001 recommended pad layout for optimal thermal conduction.

Does 1SMB5946B-13 support automated optical inspection (AOI) after reflow?

Yes. The SMB package features consistent cathode band marking and uniform surface finish compatible with standard AOI systems. Its RoHS-compliant matte tin plating provides high-contrast visual identification, and the 0.096g weight ensures stable placement during pick-and-place operations.

How does the 75V zener voltage tolerance affect circuit accuracy?

The ±5% tolerance means the actual V_Z falls between 71.25V and 78.75V at 140mA. For reference designs, this requires accounting for worst-case regulation window in feedback loop calculations. The low 5Ω Z_ZT minimizes additional error from load current variation.

Can 1SMB5946B-13 replace older 1N5365B in existing designs?

Direct replacement is possible only if mechanical constraints allow SMB footprint adoption and thermal design accommodates higher R_θJA (226°C/W vs. TO-204AA's ~100°C/W). Electrical behavior is functionally equivalent, but layout revision and thermal validation are required due to different package thermal paths.