Datasheet

LM76
SNIS109E –JANUARY 2000–REVISED MARCH 2013 www.ti.com
To understand this graph, assume that at the left hand side the system is at some nominal temperature. For the
1st event temperature rises above the upper window limit, T
HIGH
, causing INT to go active. The system responds
to the interrupt by querying the LM76's status bits and determines that T
HIGH
was exceeded, indicating that
temperature is rising. The system then reprograms the temperature limits to a value higher by an amount equal
to the desired granularity. Note that in Event Interrupt Mode, reprogramming the limits has caused a second,
known, interrupt to be issued since temperature has been returned within the window. In Comparator Interrupt
Mode, the LM76 simply stops issuing interrupts.
The 2nd event is another identical rise in temperature. The 3rd event is typical of a drop in temperature. This is
one of the conditions that demonstrates the power of the LM76, as the user receives notification that a lower limit
is exceeded in such a way that temperature is dropping.
The Critical Alarm Event activates the separate T_CRIT_A output. Typically, this would feed circuitry separate
from the processor on the assumption that if the system reached this temperature, the processor might not be
responding.
Note: Event Interrupt mode is drawn as if the user is reading the part. If the user doesn't read, the outputs would go
low and stay that way until the LM76 is read.
Figure 14. Temperature Response Diagram for ACPI Implementation
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