VRM 9.0 DC-DC Converter Design Guidelines

VRM 9.0 DC-DC Converter Design Guidelines
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Table 4, Environmental Specifications
Operating Non-Operating
Temperature VRM ambient 0°C to +60°C at full load with a
maximum rate of change of 10°C/hour and air
at a velocity of 400 LFM directed along the
connector axis
1
Ambient –40°C to 70°C
with a maximum rate of
change of 20°C/hour.
2
Humidity To 85% relative humidity. To 95% relative humidity.
Altitude 0 to 10,000 feet 0 to 50,000 feet.
Electrostatic
discharge
15 KV initialization level. The direct ESD
event shall cause no out-of-regulation
conditions.
3
25 KV initialization level.
1
See Section 1.1 for test conditions. Air flow at 400 LFM applies to modules for server and workstation systems;
desktop motherboards typically get much less airflow.
2
Thermal shock of –40°C to +70°C, 10 cycles; transfer time shall not exceed 5 minutes, duration of exposure to
temperature extremes shall be 20 minutes.
3
Includes overshoot, undershoot, and nuisance trips of over-voltage protection, over-current protection or remote
shutdown circuitry.
3.2 Shock and Vibration
PROPOSED
The VRM should not be damaged and the interconnect integrity not compromised during:
• A shock of 50G with an 11 millisecond half sine wave, non-operating, the shock to be
applied in each of the orthogonal axes.
• Vibration of 0.01G² per Hz at 5 Hz, sloping to 0.02G² per Hz at 20 Hz and maintaining
0.02G² per Hz from 20 Hz to 500 Hz, non-operating, applied in each of the orthogonal axes.
3.3 Electromagnetic Compatibility PROPOSED
Design, including materials, should be consistent with the manufacture of units that comply with
the limits of FCC Class B and CISPR22 Class B for radiated emissions.
3.4 Reliability PROPOSED
Design, including materials, should be consistent with the manufacture of units with an MTBF of
500,000 hours of continuous operation at 55°C, maximum-outputs load, and worst-case line,
while meeting specified requirements. MTBF should be calculated in accordance with MIL-
STD-217F.
3.5 Safety PROPOSED
The voltage regulator is to be UL Recognized to standard UL1950 3rd Ed., including
requirements of IEC950 and EN 60950. Plastic parts and printed wiring board are to be UL
Recognized with 94V-0 flame class.