18V 400mW Zener Diode (NXP)

Description

The 18V 400mW Zener Diode, manufactured by NXP Semiconductors (now Nexperia), is a highly reliable discrete semiconductor designed for voltage regulation and circuit protection. Unlike standard rectifier diodes that block current in the reverse direction, this Zener diode is specifically engineered to conduct in reverse once the applied voltage reaches its precise 18V "breakdown" threshold. This allows it to safely clamp excess voltage and maintain a stable reference.

Available at Tomson Electronics, this 18V Zener is capable of safely dissipating up to 400mW of power. It is an essential, low-cost component for hardware engineers and hobbyists looking to build simple voltage regulators, establish stable reference voltages for op-amps, or protect sensitive logic inputs from dangerous high-voltage spikes.

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Specifications

• Manufacturer: NXP Semiconductors (Nexperia)
• Diode Type: Zener Diode
• Zener Voltage (Vz): 18V (Typical)
• Power Dissipation (Pd): 400 mW (0.4W)
• Package Type: DO-35 (Standard Glass Axial Through-hole)
• Polarity: Marked with a cathode band
• Operating Temperature Range: -65°C to +200°C

Datasheet

Download 18V 400mW Zener Diode (NXP) Datasheet PDF

Applications

• Voltage Regulation: Providing a stable 18V DC output from a fluctuating higher-voltage DC source when paired with a series resistor.
• Overvoltage Protection: Clamping voltage spikes to safely protect sensitive downstream components like microcontrollers or sensors.
• Reference Voltages: Establishing a precise, stable 18V reference for analog-to-digital converters (ADCs) or operational amplifier comparators.
• Waveform Clipping: Shaping and clipping AC analog signals in audio circuits and function generators.

Frequently Asked Questions (FAQ)

Q: How do I wire a Zener diode in my circuit?
A: To use a Zener diode for voltage regulation or clamping, it must be installed in reverse bias. This means you connect the cathode (the side with the black band) to the positive voltage source, and the anode to ground. If installed in forward bias, it will act like a normal diode and drop about 0.7V.

Q: Do I need a resistor to use this diode?
A: Yes! When a Zener diode reaches its breakdown voltage (18V), its resistance drops dramatically. If you do not place a current-limiting series resistor between the power source and the Zener diode, it will draw excessive current, overheat, and destroy itself.

Q: What happens if my circuit draws more than 400mW of power?
A: If the power dissipation (Current × Zener Voltage) exceeds the 400mW rating, the diode will burn out. For circuits requiring higher currents, you should use the Zener diode to drive a higher-power series pass transistor, or select a Zener diode with a higher wattage rating (such as a 1W 1N4746A).

Package Includes

• 1 × 18V 400mW Zener Diode (NXP)