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TFX12V Power Supply Design Guide
Thin Form Factor with 12-V Connector
Version 2.0
Table 15. Over Voltage Protection
Output Minimum Nominal Maximum Unit
+12 V1DC 13.4 15.0 15.6 Volts
+12 V2DC 13.4 15.0 15.6 Volts
+5 VDC 5.74 6.3 7.0 Volts
+3.3 VDC 3.76 4.2 4.3 Volts
2.4.2 Short-circuit Protection
An output short circuit is defined as any output impedance of less than 0.1 ohms. The power supply shall
shut down and latch off for shorting the +3.3 VDC, +5 VDC, or +12 VDC rails to return or any other rail.
Shorts between main output rails and +5 VSB shall not cause any damage to the power supply. The power
supply shall either shut down and latch off or fold back for shorting the negative rails. +5 VSB must be
capable of being shorted indefinitely, but when the short is removed, the power supply shall recover
automatically or by cycling PS_ON#. The power supply shall be capable of withstanding a continuous short
circuit to the output without damage or overstress to the unit (for example, to components, PCB traces, and
connectors) under the input conditions specified in Section 3.1.
2.4.3 No-load Operation
No damage or hazardous condition should occur with all the DC output connectors disconnected from the
load. The power supply may latch into the shutdown state.
2.4.4 Over Current Protection
Overload currents applied to each tested output rail cause the output to trip before reaching or exceeding 240
VA. For testing purposes, the overloaded currents should be ramped at a minimum rate of 10 A/s starting
from full load.
2.4.5 Over-temperature Protection
As an option, the power supply may include an over-temperature protection sensor, which can trip and shut
down the power supply at a preset temperature point. Such an overheated condition is typically the result of
internal current overloading or a cooling fan failure. If the protection circuit is non-latching, then it should have
hysteresis built in to avoid intermittent tripping.
2.4.6 Output Bypass
The output return may be connected to the power supply chassis, and will be connected to the system
chassis by the system components.