Diodes Incorporated 1SMB5948B-13

Overview

1SMB5948B-13 from Diodes Incorporated is a 3.0W surface-mount power Zener diode with a nominal zener voltage of 91V (±5%), 4.1Ω dynamic impedance at 200mA test current, 0.25µA maximum reverse leakage at 69.2V, and ESD rating >16kV (HBM). It operates from −65°C to +150°C and is used for precision voltage regulation and overvoltage protection in industrial power supplies.

For engineers reviewing the 1SMB5948B-13 datasheet, 1SMB5948B-13 pinout, 1SMB5948B-13 application, or 1SMB5948B-13 equivalent, key selection criteria include zener voltage tolerance, power derating above +25°C, thermal resistance (R_θJA = 226°C/W), and SMB package compatibility with automated SMT assembly.

Technical Context

This Zener diode functions as a shunt voltage regulator by maintaining a stable 91V breakdown across its terminals under reverse bias when current exceeds the knee threshold. Its low dynamic impedance (4.1Ω) ensures minimal voltage variation under load changes, while the 3.0W power rating supports transient energy clamping in DC bus protection circuits.

The device uses a copper alloy leadframe with matte tin plating, conforms to RoHS 3 and halogen/antimony-free "Green" standards, and features a cathode band polarity indicator. Moisture sensitivity level is rated at Level 1 per J-STD-020, enabling uncomplicated reflow processing without baking.

Key Specifications

Pinout & Package

Package: SMB (Surface Mount Body), molded plastic case with UL 94V-0 flammability rating, cathode band marking, and 0.096g mass. Dimensions: 3.30–3.94mm (L) × 4.06–4.57mm (W) × 1.96–2.21mm (H).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMBJ91A and 1N5377B, the 1SMB5948B-13 uniquely balances SMT manufacturability, ±5% regulation accuracy, and 3.0W continuous dissipation-making it optimal for automated production of compact, high-reliability power management circuits.

Availability

1SMB5948B-13 is available at Aetrix Electronics and suitable for industrial power supplies, automotive battery monitoring systems, and telecom line card protection requiring stable component supply with guaranteed long-term sourcing.

Supply support for 1SMB5948B-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 centers across Asia and manufacturing in Taiwan and China.

The SMB Zener series targets cost-sensitive, high-volume applications demanding robust voltage regulation in compact SMT packages-especially for industrial, computing, and communications infrastructure.

FAQ

What is the maximum continuous reverse voltage that can be safely applied to 1SMB5948B-13 without breakdown?

The device exhibits a nominal zener voltage of 91V with ±5% tolerance, meaning breakdown occurs between 86.45V and 95.55V. Applying a reverse voltage below 86.45V ensures no significant conduction; operation above 95.55V risks exceeding the 3.0W power limit unless current is strictly limited by external series resistance.

How does thermal derating affect power handling at elevated ambient temperatures?

At +25°C ambient, the device dissipates up to 550mW; above this, it derates at 4.4mW/°C. At +85°C ambient, usable power drops to 286mW. For full 3.0W operation, the terminal temperature must be held at ≤+75°C using appropriate PCB copper area and airflow per AP02001 layout guidelines.

Can 1SMB5948B-13 replace a 1N4749A in an existing design?

No-1N4749A is a 1W, DO-41 packaged 24V Zener. The 1SMB5948B-13 is a 91V, 3W SMB device with different voltage, power, package, and thermal characteristics. Direct substitution would cause catastrophic overvoltage failure. Equivalent 24V SMB Zeners include 1SMB5924B (24V, 3W).

Is the cathode band orientation consistent across all SMB-packaged Zeners from Diodes Incorporated?

Yes-the cathode band is always located on the same end of the SMB package body, aligned with the marking code (B948 for this part). This matches JEDEC standard SMB polarity definition and ensures correct orientation during automated placement and visual inspection.