Intel ATX 0.9 - Manual (Page 19)

Intel ATX Power Supply Design Guide
Version 0.9
Page 19
3.5 Output Protection
3.5.1 Overvoltage Protection
The overvoltage sense circuitry and reference shall reside in packages that are separate and
distinct from the regulator control circuitry and reference. No single point fault shall be
able to cause a sustained overvoltage condition on any or all outputs. The supply shall
provide latch-mode overvoltage protection as defined below.
Table 11: Overvoltage Protection
Output Min. Nom. Max. Unit
+12VDC - - 15.6 Volts
+5VDC 5.74 6.3 7.0 Volts
+3.3VDC 3.76 4.2 4.3 Volts
3.5.2 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 +3.3VDC, +5VDC, or +12VDC
rails to return or any other rail. Shorts between main output rails and +5VSB 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. The +5VSB must be capable of being
shorted indefinitely, but when the short is removed, the power supply shall recover
automatically or by cycling the PS_ON#. The power supply shall be capable of
withstanding a continuous short-circuit to the output without damage or overstress to the
unit (components, PCB traces, connectors, etc.) under the input conditions specified in
Section 3.1. The maximum short-circuit energy in any output shall not exceed 240 VA.
3.5.3 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.
3.5.4 Overcurrent Protection
Overload currents applied to each tested output rail will cause the output to trip before
reaching or exceeding 240 VA. For testing purposes, the overload currents should be
ramped at a minimum rate of 10 A/s starting from full load.
3.5.5 Output Bypass
The output return may be connected to the power supply chassis. The return will be
connected to the system chassis by the system components.