JAJSFV7C September 2016 – March 2020 UCD90160A
PRODUCTION DATA.
This feature allows with the use of up to 3 GPIs to enable and disable any rail. This is useful for implementing system low-power modes and the Advanced Configuration and Power Interface (ACPI) specification that is used for operating system directed power management in servers and PCs. In up to 8 system states, the power system designer can define which rails are on and which rails are off. If a new state is presented on the input pins, and a rail is required to change state, it does so with regard to its sequence-on or sequence-off dependencies.
The OPERATION command is modified when this function causes a rail to change its state. This means that the ON_OFF_CONFIG for a given rail must be set to use the OPERATION command for this function to have any effect on the rail state. The first three pins configured with the GPI_CONFIG command are used to select 1 of 8 system states. Whenever the device is reset, these pins are sampled and the system state, if enabled, are used to update each rail state. When selecting a new system state, changes to the status of the GPIs must not take longer than 1 microsecond. See the UCD90xxx Sequencer and System Health Controller PMBus Command Reference for complete configuration settings of PIN_SELECTED_RAIL_STATES.
| GPI 2 State | GPI 1 State | GPI 0 State | System State |
|---|---|---|---|
| NOT Asserted | Not Asserted | Not Asserted | 0 |
| NOT Asserted | Not Asserted | Asserted | 1 |
| NOT Asserted | Asserted | Not Asserted | 2 |
| NOT Asserted | Asserted | Asserted | 3 |
| Asserted | Not Asserted | Not Asserted | 4 |
| Asserted | Not Asserted | Asserted | 5 |
| Asserted | Asserted | Not Asserted | 6 |
| Asserted | Asserted | Asserted | 7 |