Zener Diodes — Voltage Regulation, TVS Protection & Voltage Reference

Zener diodes are semiconductor devices engineered to operate reliably in reverse breakdown, providing a stable reference voltage across a wide range of reverse currents. They serve three critical functions in electronic design: precise voltage regulation, overvoltage transient protection, and low-noise voltage references for analogue circuits. At ADD Components, we supply Zener diodes and transient voltage suppressors from Vishay, ON Semiconductor, STMicroelectronics, Nexperia, and Diodes Incorporated, covering breakdown voltages from 1.8 V to over 400 V. This guide walks through the main Zener diode categories, key parameters, and a representative selection of parts we source for engineering and procurement teams.

Sub-Types / Categories

Standard Zener Voltage Regulators

Standard Zener diodes provide a stable, temperature-compensated reference voltage for shunt regulation, level shifting, and overvoltage clamping in low-power circuits. They are rated by nominal Zener voltage (VZ), power dissipation (typically 250 mW to 5 W), and tolerance (commonly ±5% or ±2% for tighter applications). The Zener breakdown mechanism dominates below approximately 5.6 V, exhibiting a negative temperature coefficient, while avalanche breakdown above 5.6 V produces a positive temperature coefficient. Around 5.6 V, the two effects cancel, yielding near-zero temperature drift, which makes the 5.6 V Zener a popular choice for temperature-stable references. Classic through-hole diode Zeners include the BZX55C series (500 mW, DO-35) and the 1N4728A to 1N4764A series (1 W, DO-41), while SMD diode equivalents like the BZX84C series (250 mW, SOT-23) and BZT52C series (500 mW, SOD-123) suit modern compact designs.

Precision Voltage Reference Zeners

Precision Zener diodes achieve tight initial accuracy of ±1% or better, combined with exceptionally low temperature coefficients below 50 ppm/°C. These parts function as buried Zener references or temperature-compensated Zeners that integrate a series diode with opposing temperature coefficient to cancel drift. Though often implemented as integrated circuits today, discrete precision Zeners including selected grades of the BZX55C and BZX84C families remain critical in analogue instrumentation, data acquisition systems, and calibration equipment. Nexperia and ON Semiconductor offer the BZX84 series in graded tolerance bands (A for ±1%, B for ±2%, C for ±5%), allowing designers to balance cost against precision. For ultra-stable applications requiring long-term drift below 20 ppm, Vishay's precision Zener references provide excellent noise performance critical for high-resolution ADC and DAC circuits.

Transient Voltage Suppressors (TVS)

Transient voltage suppressor diodes are a specialised class of Zener diodes designed to absorb high-energy transient surges from electrostatic discharge (ESD), inductive load switching, and lightning-induced events. Unlike standard Zeners, TVS diodes feature a large junction area in a low-inductance package, capable of dissipating peak pulse power from 200 W to over 5000 W for durations of 10/1000 μs. Bidirectional TVS diodes (suffix CA) protect AC signal lines and polarity-independent nodes, while unidirectional types (suffix A) suit DC power rails. The SMAJ series (400 W, SMA package) from STMicroelectronics addresses data line and low-power rail protection, the SMBJ series (600 W, SMB) covers general-purpose transient suppression, and the 1.5KE series (1500 W, DO-201) tackles higher-energy threats in industrial and automotive environments. Vishay's P6KE and SM6T series round out the through-hole diode and SMD diode TVS portfolios respectively. Key selection criteria include stand-off voltage (VWM), breakdown voltage (VBR), clamping voltage (VC), and peak pulse power rating (PPP).

Key Selection Parameters

• Nominal Zener Voltage (VZ): The specified reverse breakdown voltage at the test current IZT. Choose a value that provides adequate headroom above the regulated voltage in shunt regulator configurations.

• Power Dissipation (Ptot): The maximum continuous power the device can dissipate. Derate for ambient temperature above 25°C. Higher-power Zeners (1 W, 5 W) require careful PCB layout or heatsinking.

• Zener Tolerance: Standard ±5% suffices for most clamping and regulation. Select ±2% or ±1% for precision references and analogue circuits where absolute voltage matters.

• Dynamic Impedance (ZZ): The small-signal resistance in the breakdown region. Lower Zz yields better line and load regulation. Zz decreases with increasing Zener current.

• Temperature Coefficient (TC): Measured in mV/°C or %/°C. For Zeners below 5 V, the negative TC dominates; above 6 V, the positive TC dominates. Use Zener-stacked or temperature-compensated configurations for high-stability designs.

• Leakage Current (IR): Reverse leakage below the breakdown knee. Important for battery-powered circuits where nanoamp-level leakage matters.

• Package: Through-hole diode packages (DO-35, DO-41) for breadboarding and repair; surface mount diode packages (SOD-123, SOD-323, SOT-23) for production. TVS diodes add SMA, SMB, SMC, and DO-214 packages.

Representative Parts We Source

Send Us Your Diode Requirements

ADD Components provides the complete range of Zener diodes and transient voltage suppressors for voltage regulation, overvoltage protection, and precision reference applications. From the smallest BZX84C3V3 in SOT-23 to high-power 1.5KE TVS diodes, we deliver authentic factory-original parts with full traceability and competitive pricing. Our engineering procurement team can help identify alternative parts, consolidate your BOM, and secure consistent supply across Vishay, ON Semiconductor, STMicroelectronics, Nexperia, and Diodes Incorporated product lines.

Submit your part numbers or bill of materials today for a same-day quotation. We ship internationally and support both through-hole diode and surface mount diode requirements.

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