FW82801EB Intel, FW82801EB Datasheet - Page 154

• Manufacturer Part Number: FW82801EB
• Manufacturer: Intel

Specifications of FW82801EB

• Lead Free Status / RoHS Status: Not Compliant

Functional Description
5.13.7.4
154
Table 66. Transitions Due to Power Failure
Note: Although PME_EN is in the RTC well, this signal cannot wake the system after a power loss.
Sx-G3-Sx, Handling Power Failures
Power failures can occur if the AC power is cut (a real power failure) or if the system is unplugged.
In either case, PWROK and RSMRST# are assumed to go low.
Depending on when the power failure occurs and how the system is designed, different transitions
could occur due to a power failure.
The AFTER_G3 bit provides the ability to program whether or not the system should boot once
power returns after a power loss event. If the policy is to not boot, the system remains in an S5 state
(unless previously in S4). There are only three possible events that will wake the system after a
power failure.
The ICH5 monitors both PWROK and RSMRST# to detect for power failures. If PWROK goes
low, the PWROK_FLR bit is set. If RSMRST# goes low, PWR_FLR is set.
PME_EN is cleared by RTCRST#, and PME_STS is cleared by RSMRST#.
State at Power Failure
1. PWRBTN#: PWRBTN# is always enabled as a wake event. When RSMRST# is low (G3
2. RI#: RI# does not have an internal pull-up. Therefore, if this signal is enabled as a wake event,
3. RTC Alarm: The RTC_EN bit is in the RTC well and is preserved after a power loss. Like
state), the PWRBTN_STS bit is reset. When the ICH5 exits G3 after power returns
(RSMRST# goes high), the PWRBTN# signal is already high (because V
before RSMRST# goes high) and the PWRBTN_STS bit is 0.
it is important to keep this signal powered during the power loss event. If this signal goes low
(active), when power returns the RI_STS bit is set and the system interprets that as a wake
event.
PWRBTN_STS the RTC_STS bit is cleared when RSMRST# goes low.
S0, S1, S3
S4
S5
AFTERG3_EN bit
1
0
1
0
1
0
Transition When Power Returns
Intel
®
82801EB ICH5 / 82801ER ICH5R Datasheet
S5
S0
S4
S0
S5
S0
CC
-standby goes high