LM87 datasheet(19/32 Pages) NSC

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Functional Description (Continued)

9.0 WATCHDOG LIMIT COMPARISONS AND

INTERRUPT STRUCTURE

Figure 10 depicts the Interrupt Structure of the LM87. The

LM87 can generate Interrupts as a result of each of its

internal WATCHDOG registers on the analog, temperature,

and fan inputs.

External Interrupts can come from the following sources.

While the label suggests a specific type or source of Inter-

rupt, this label is not a restriction of its usage, and it could

come from any desired source:

•

Chassis Intrusion:

This is an active high interrupt from

any type of device that detects and captures chassis

intrusion violations. This could be accomplished me-

chanically, optically, or electrically, and circuitry external

to the LM87 is expected to latch the event. The design of

the LM87 allows this input to go high even with no power

applied to the LM87, and no clamping or other interfer-

ence with the line will occur. This line can also be pulled

low for at least 20 ms by the LM87 to reset a typical

Chassis Intrusion circuit. This reset is activated by setting

Bit 7 of CI Clear Register (46h) high. The bit in the

10099531

FIGURE 10. Interrupt Structure

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