onsemi SZ1SMB5917BT3G

Overview

SZ1SMB5917BT3G from onsemi is a 3 W surface-mount Zener diode with nominal Zener voltage of 4.7 V (±5%), maximum Zener impedance of 79.8 Ω at 5 mA test current, and reverse leakage current ≤1.5 μA at 3.76 V. It operates across −65 °C to +150 °C and is AEC−Q101 qualified for automotive power rail clamping and voltage reference applications.

For engineers reviewing the SZ1SMB5917BT3G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener tolerance, thermal derating above 75 °C, junction-to-lead thermal resistance (40 °C/W), and Pb-free SMB package compatibility with automated SMT assembly.

Technical Context

This device functions as a precision DC voltage regulator and overvoltage clamp in low-power analog and digital supply rails. Its 4.7 V nominal Zener voltage targets 5 V system logic rails, with tight ±5% tolerance and low dynamic impedance enabling stable regulation under varying load currents.

The SMB package provides top-side or bottom-side PCB mounting flexibility, modified L-bend leads for enhanced pad adhesion, and UL 94 V−0 flammability rating. Thermal performance is defined by 3.0 W steady-state dissipation at TL = 75 °C and 550 mW at TA = 25 °C, with linear derating above both thresholds.

Key Specifications

Pinout & Package

Package: SMB (Case 403A), surface-mount plastic package with cathode polarity band, Pb-free, UL 94 V−0 rated, 2.30 mm nominal width, 3.56 mm nominal length, 1.02 mm nominal height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1SMB5917BT3G, SZ1SMB5917BT3G adds AEC−Q101 qualification and PPAP capability for automotive programs, while BZX84-C4V7LT1G offers footprint reduction at the cost of 90% lower power handling-making it viable only in non-power-critical signal conditioning roles.

Availability

SZ1SMB5917BT3G is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor signal conditioning, consumer USB-C power delivery adapters, and medical portable diagnostic devices requiring stable component supply and long-term lifecycle assurance.

Supply support for SZ1SMB5917BT3G 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

onsemi (Semiconductor Components Industries, LLC) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The SZ1SMB59xxT3G series is designed specifically for automotive-grade voltage regulation and transient suppression, emphasizing AEC−Q101 reliability, Pb-free compliance, and robust thermal performance in harsh environments.

FAQ

What is the Zener voltage tolerance of SZ1SMB5917BT3G?

The SZ1SMB5917BT3G has a nominal Zener voltage of 4.7 V with a tolerance of ±5%, meaning its actual breakdown voltage falls between 4.46 V and 4.94 V at 5 mA test current. This tolerance is confirmed in the Electrical Characteristics table on page 3 of the onsemi datasheet and applies across the full operating temperature range of −65 °C to +150 °C. The SZ1SMB5917BT3G maintains this specification under steady-state conditions with proper thermal management.

Is SZ1SMB5917BT3G suitable for automotive applications?

Yes, SZ1SMB5917BT3G is explicitly AEC−Q101 qualified and PPAP capable, as stated in the Features section of the onsemi datasheet. Its construction-including void-free transfer-molded plastic, modified L-bend leads, and UL 94 V−0 flammability rating-meets automotive reliability requirements. The SZ prefix denotes compliance with automotive site and control change protocols, making SZ1SMB5917BT3G appropriate for under-hood and infotainment systems where extended temperature operation and process traceability are mandatory.

What is the maximum power dissipation of SZ1SMB5917BT3G at ambient temperature?

SZ1SMB5917BT3G delivers 550 mW maximum steady-state power dissipation at T_A = 25 °C, with linear derating of 4.4 mW/°C above that temperature. This value is specified in the Maximum Ratings table and assumes use on an FR-4 board with the recommended footprint. At T_A = 75 °C, the device is limited to 3.0 W only when lead temperature (T_L) is maintained at 75 °C-requiring direct thermal coupling to a copper plane or heatsink. The SZ1SMB5917BT3G's 40 °C/W junction-to-lead thermal resistance enables this higher power mode when properly mounted.

How does the ESD rating of SZ1SMB5917BT3G compare to standard industrial Zeners?

SZ1SMB5917BT3G features Class 3 Human Body Model (HBM) ESD rating (>16 kV), significantly exceeding typical industrial Zener diodes rated at Class 2 (≥4 kV) or unqualified parts. This high ESD immunity is achieved through optimized junction design and packaging, supporting robust handling in automotive manufacturing lines and reducing field failures due to electrostatic discharge during assembly. The SZ1SMB5917BT3G datasheet confirms this rating in the Features section and positions it as a key advantage for high-reliability applications.

Can SZ1SMB5917BT3G be used in parallel for higher current handling?

No, SZ1SMB5917BT3G should not be operated in parallel without external balancing resistors due to inherent Zener voltage tolerances (±5%) and temperature coefficient variations. Even matched units exhibit unequal current sharing, risking thermal runaway in one device. For higher current applications, select a single higher-power Zener (e.g., 5 W or 10 W SMB variants) or implement active regulation. The onsemi datasheet does not recommend parallel operation for the SZ1SMB5917BT3G and specifies all ratings for individual device use.