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Intel ATX Power Supply Design Guide
Version 0.9
7. Reliability
7.1 Component Derating
The following component derating guidelines shall be followed:
∙Semiconductor junction temperatures shall not exceed 110 °C with an ambient of 50 °C. Any exceptions are subject to final approval.
∙Inductor case temperature shall not exceed safety agency requirements.
∙Capacitor case temperature shall not exceed 95% of rated temperature.
∙Resistor wattage derating shall be > 30%.
∙Component voltage and current derating shall be > 10% at 50 °C. Any exceptions are subject to final approval.
∙Magnetic saturation of any transformer will not be allowed under any line, load, startup, or transient condition including 100% transients on the five main outputs or +5VSB.
7.2Mean Time Between Failures (MTBF)
The MTBF of the power supply shall be calculated utilizing the
∙Full rated load
∙120 VAC input
∙Ground benign
∙25 °C ambient.
The calculated MTBF of the power supply shall be greater than 30,000 hours under the following conditions:
∙Full rated load
∙120 VAC input
∙Ground benign
∙50 °C ambient.
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