Zener diodes

Haiben is an electronic components supplier based in Shenzhen, China, founded in 2013. Our official catalogue includes a dedicated Zener Diodes category, and Zener diodes form part of the Weforsemi discrete semiconductor range produced by our wholly-owned subsidiary. This page is written for purchasing staff and hardware engineers who need to specify and buy Zener diodes, and it explains what these parts are used for, how the common variants are described, and what we confirm with you before a quotation is issued.

What Zener diodes are bought for

A Zener diode is a diode designed to operate in reverse breakdown at a defined nominal Zener voltage. When the reverse voltage across it reaches that value, the device conducts and holds the voltage across itself at approximately that level, which is why it appears in so many designs as a simple reference or clamp. Engineers and buyers typically purchase Zener diodes for three purposes:

• Shunt voltage regulation. A Zener diode in parallel with a load, fed through a series resistor, holds a roughly constant voltage across the load. The resistor drops the difference between the supply and the Zener voltage, and the operating current is set by its value together with the power rating of the diode.
• Voltage reference. Because the breakdown voltage is defined at manufacture, a Zener diode can provide a fixed reference for comparators, regulators and bias networks.
• Overvoltage clamping and protection. Placed across a signal line or supply rail, a Zener diode limits excursions above its nominal voltage, protecting sensitive inputs downstream.

If your team is new to the component, our article on what a Zener diode is covers the operating principle, and Zener diode as a voltage regulator walks through the shunt regulator arrangement and the role of the series resistor in setting operating current.

Voltage variants and how they are specified

On the Weforsemi range, specification points that buyers ask for include 12 V, 5 V and 3.3 V Zener variants. These are the voltage values requested for a given design; they are not presented here as stocked model numbers, and exact part numbers and datasheet values are confirmed at quotation. That distinction matters when you are building a BOM: the nominal Zener voltage is only one of several parameters that define a usable part.

When you raise an enquiry, the points we confirm on the datasheet are:

• Nominal Zener voltage (V_Z). The reverse voltage at which the diode is specified to break down, for example 3.3 V, 5 V or 12 V.
• Voltage tolerance. The permissible band around the nominal value, usually expressed as a percentage or as a lettered tolerance group, since the breakdown voltage varies from unit to unit and with current.
• Power dissipation. The maximum continuous power the package can dissipate, which together with the series resistor determines the maximum operating current and therefore the load range the shunt regulator can support.
• Package and mounting. Through-hole or surface-mount, and the specific outline, which affects layout, thermal behaviour and assembly process.

Where a design needs a sharp reference rather than a clamp, check the datasheet curves for the tolerance band and the dynamic resistance near the intended operating current before fixing the series resistor.

SMD Zener diodes and packages

Most new boards are assembled with surface-mount devices, so a large share of Zener enquiries are for SMD packages. Surface-mount Zener diodes are commonly supplied in small two-terminal plastic packages and in glass-bodied MELF-style outlines, with the package chosen according to the power dissipation required and the board space available. Larger power-rated Zeners move to packages with better thermal paths, which is why the package and the power rating are always read together rather than separately.

If your BOM also carries rectifiers, switching diodes or TVS devices, our SMD diodes category shows how the surface-mount diode range is organised, and the same ordering discipline applies: state the function, the voltage and current requirements, and the preferred package, and we will confirm the matching datasheet values.

Ordering notes: what we confirm on the datasheet

Zener diodes are easy to over-specify and easy to under-specify. To keep quotations accurate, please include the following in your enquiry:

• The nominal Zener voltage and the tolerance you can accept.
• The expected operating current, or the supply voltage, load current and series resistor value if the regulator design is fixed.
• The required power dissipation and the preferred package, including any assembly constraints.
• Quantities, required delivery date and any documentation you need with the shipment.

We will then confirm the exact part number, the datasheet values for that part, and availability. Because the Weforsemi line covers a broad discrete semiconductor range, we can also discuss alternative voltage variants or packages if your first choice does not fit the schedule.

Frequently asked questions

Can I get a quotation for 5 V and 12 V Zener diodes from the Weforsemi line?

Yes. 5 V, 12 V and 3.3 V are specification points buyers commonly ask for on this range. Send us the nominal voltage, tolerance, operating current and package you need, and we will confirm the exact part number and datasheet values at quotation.

Do you list Zener part numbers and electrical ratings on this page?

No. This page explains how Zener diodes are specified rather than listing model numbers or ratings. Exact part numbers, voltage tolerances, power dissipation and package details are confirmed on the datasheet when we quote.

How do I choose between a through-hole and an SMD Zener diode?

The choice usually follows your assembly process and the power dissipation required. SMD packages suit reflow-assembled boards with modest dissipation, while larger power-rated devices need packages with better thermal performance. Tell us the mounting method and the power you need to dissipate, and we will confirm suitable options on the Weforsemi line.