TFX12V Power Supply Design Guide
Thin Form Factor with 12 V Connector
Version 2.0
Table 6: Typical Power Distribution for 270 W SFX12V Configurations
Output | Minimum | Maximum | Peak |
| Current | Current | Current |
| (amps) | (amps) | (amps) |
+12 V1DC | 1.0 | 7.0 | 9.0 |
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+12 V2DC | 1.0 | 13.0 |
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+5 VDC | 0.3 | 18.0 |
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+3.3 VDC | 0.5 | 17.0 |
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0.0 | 0.3 |
| |
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+5 VSB | 0.0 | 2.0 | 2.5 |
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Note: Total combined output of 3.3 V and 5 V is 
20 W
Peak currents may last up to 17 seconds with not more than one occurrence per minute
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| 270W Cross Regulation |
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| (5V rail + 3.3V rail vs. 12V1 +12V2) |
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| 120 |
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t s ) | 100 |
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( w a t | 80 |
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e r |
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| Combined Power | |
o w | 60 |
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| (5V rail + 3.3V rail) | ||
p |
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. 3 V | 40 |
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3 |
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+ | 20 |
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V |
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5 |
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| 0 |
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| 0 | 40 | 80 | 120 | 160 | 200 | 240 |
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| 12V power (watts) |
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Figure 5 Cross Loading Graph for 270W Configuration
2.2.4Power Limit / Hazardous Energy Levels
Under normal or overload conditions, no output shall continuously provide 240 VA under any conditions of load including output short circuit, per the requirement of UL 1950/CSA 950 / EN 60950/IEC 950 specification.
2.2.5Efficiency General
The power supply should be a minimum of 70% efficient under “Full” load, 70% under “typical” load, and 60% in a “light” load idle condition. The efficiency of the power supply should be tested at nominal input voltage of
16
