Description
The 15V 0.5W Zener diode is a common component used for establishing a stable 15V reference voltage or protecting circuits from transient voltage spikes. The industry-standard part number for this specification is the 1N5245 (or the BZX79-C15 series).
Technical Specifications
| Parameter | Specification |
| Nominal Zener Voltage ($V_Z$) | 15V |
| Power Dissipation ($P_D$) | 0.5W (500mW) |
| Package Type | DO-35 (Small Glass Axial) |
| Tolerance | $\pm 5\%$ |
| Operating Temperature | -65°C to +200°C |
Understanding the Zener Principle
This component is designed to operate in the reverse breakdown region. When the input voltage exceeds 15V, the diode begins to conduct, clamping the output voltage to a stable 15V by shunting excess current to ground.
To function as a regulator, you must use a series current-limiting resistor ($R_s$). This is critical: without this resistor, the diode would draw excessive current from your supply, exceed its 500mW power limit, and likely fail, typically as a short circuit.
Application & Safety Guidelines
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Thermal Management: To keep this 500mW device operating safely, ensure the current ($I_Z$) flowing through it does not exceed the limit. Using the formula $I_{Zmax} = P_D / V_Z$, your maximum current should be kept below ~33mA ($0.5W / 15V$).
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Procurement: You requested 2 pieces. These are widely available at any electronics component retailer; search for “1N5245” to find this exact specification.
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Troubleshooting: If the voltage on your 15V rail is zero or lower than expected, check the Zener diode. A failed Zener diode typically measures as a dead short (near 0 ohms) in both directions on a multimeter.
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