PC87366 Datasheet, PDF (55/240 Pages) National Semiconductor (TI) – 128-Pin LPC SuperI/O with System Hardware Monitoring, MIDI and Game Ports

2.0 Device Architecture and Configuration (Continued)
2.8.12 SuperI/O Configuration D Register (SIOCFD)
This is a battery-backed register.
Location: Index 2Dh
Type:
Varies per bit
Bit
7
6
5
4
3
Name
LED Polarity Last PSON PSON
Control
State
Polarity
Crowbar Timeout
Reset
0
0
Strap
1
1
2
1
Resume
Last PSON
State
Power
Supply Off
0
0
0
Power
Button
Mode
0
Bit
Description
7 LED Polarity Control. This is a R/W bit. It determines if the LED outputs are active high or active low when
they are lit.
0: Active high (default at V_SB power-up reset)
1: Active low
6 Last Power Supply On State. This is a RO bit. When operating in Legacy mode (bit 0 of this register is set to 0), this
bit reflects the state of the PSON pin sampled during the last power failure (no V_SB), regardless of the polarity of PSON.
0: Off
1: On
5 Power Supply On Polarity. This is a RO bit. The polarity of PSON is determined during V_SB power-up by the
PSONPOL strap.
4-3 Crowbar Timeout. This is a R/W bit.
Bits
5 4 Value (Seconds)
0 0 0.5 to 0.75
0 1 1.0 to 1.25
1 0 1.25 to 1.5
1 1 2.0 to 2.25 (default at V_PP power-up reset)
2 Resume Last Power Supply On State. This is a R/W bit. When it is set to 1, PSON resumes its last state, sampled
during the last power failure, after power returns. When this bit is set to 0, the PSON state is determined by the
SLPS3 state.
0: SLPS3 (default at V_PP power-up reset)
1: Last PSON state. For correct operation, the system’s ACPI controller must be configured to resume to OFF.
This enables the power supply control logic to know the state of the chipset ACPI state machine after power
failure (no V_DD and V_SB).
1 Power Supply Off. This is a R/W bit. It always returns 0 when read. When using Legacy mode (bit 0 is set to
0) and setting this bit to 1, this bit inactivates the PSON output, thereby shutting off the power supply.
0: No action (default at V_PP power-up reset)
1: Inactivate PSON in Legacy mode
0 Power Button Mode. This is a R/W bit.
0: Legacy (default at V_SB power-up reset)
1: ACPI
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