The PS SYSMON unit has two normal temperature lower alarm threshold registers; ALARM_LOWER_TEMP_LPD and ALARM_LOWER_TEMP_FPD. The PL SYSMON unit has one normal temperature lower alarm threshold register; ALARM_LOWER_TEMP_PL.
The temperature alarm is set when the measured temperature exceeds the value in the ALARM_UPPER_TEMP_xx register. The temperature at which the alarm is cleared depends on the [threshold_mode] bit setting in the lower alarm threshold register. The alarm deasserts either immediately after the temperature drops below the upper limit, or when hysteresis is enabled, when the temperature reaches the lower limit.
All of these registers define a lower temperature threshold that can be used in one of the following ways.
•Normal Lower Threshold Mode
In normal mode, the alarm is asserted when the temperature is below the lower threshold. When the temperature returns to between the upper and lower thresholds, the alarm is deasserted. This mode is selected when bit  of the lower threshold register is set to 1.
•Hysteresis Lower Threshold Mode
In hysteresis mode, the alarm is asserted when the temperature goes above the upper threshold and deasserts when it falls below the lower threshold. The hysteresis mode is selected when bit  of the lower threshold register is set to 0.