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Electrical

36 613768

held at zero potential with respect to ground. PS_ON# has no effect on the +12VSB

output, which is always enabled whenever the AC power is present. To support

systems with ALPM this is required for all power supplies. The power supply may be

asked to turn back on before all voltage rails have turned off. The power supply must

be able to turn back on via a change in the PS_ON# signal after 100 ms of the

PS_ON# signal being de-asserted. The power supply shall not latch into a shutdown

state when PS_ON# is driven active by pulses between 10 ms to 100 ms during the

decay of the power rails. When PS_ON# de-asserts (turn on the PSU) with a time

that is greater than 100 ms, from when it is first asserted (turns off), the PSU must

respond to this request and turn back on all voltages rails no matter where the

voltage rails are in ramping down the voltage to an Off state.

Table 4-10 lists PS_ON# signal characteristics.

The power supply shall provide an internal pull-up to TTL high. The power supply shall

also provide debounce circuitry on PS_ON# to prevent it from oscillating on/off at

startup when activated by a mechanical switch. The DC output enable circuitry must

be SELV-compliant in case a human touches the PS_ON# pin.

The power supply shall not latch into a shutdown state when PS_ON# is driven active

by pulses between 10 ms to 100 ms during the decay of the power rails. When

PS_ON# de-asserts (turn on the PSU) with a time that is greater than 100 ms, from

when it is first asserted (turns off), the PSU must respond to this request and turn

back on all voltages rails no matter where the voltage rails are in ramping down the

voltage to an Off state.

Table 4-10: PS_ON# Signal Characteristics

Parameter Minimum Maximum

0 0.8 V

= 0.4 V) - -1.6 mA

= 200 uA) 2.0 V -

open circuit - -5.25 V

Ripple / Noise 400 mV p-p

NOTES:

1. Negative current indicates that the current is flowing from the power supply to the

motherboard.

2. Due to PS_ON# toggle on/off frequently, system and PSU component’s reliability

should be considered based on the days, months, or years of claimed warranty

listed on product specification. Refer to Section 10.2

for more details about PSU

design consideration for S0ix mode.

Intel ATX12VO User Manual

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