ADM1024ARU datasheet(19/28 Pages) AD

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ADM1024

–19–

REV. 0

INTERRUPT STATUS MIRROR REGISTERS

Whenever a bit in one of the Interrupt Status Registers is updated,

the same bit is written to duplicate registers at addresses 4Ch

and 42h. These registers allow a second management system to

access the status data without worrying about clearing the data.

The data in these registers is for reading only and has no effect

on the interrupt output.

TEMPERATURE INTERRUPT MODES

The ADM1024 has two distinct methods of producing interrupts

for out-of-limit temperature measurements from the internal or

external sensors. Temperature errors can generate an interrupt

on the

INT pin along with other interrupts, but there is also

a separate

THERM pin that generates an interrupt only for

temperature errors.

Operation of the

INT output for temperature interrupts is

illustrated in Figure 22. Assuming that the temperature starts off

within the programmed limits and that temperature interrupt

sources are not masked,

INT will go low if the temperature

measured by any of the internal or external sensors exceeds the

programmed high temperature limit for that sensor, or the hard-

ware limits in register 13h, 14h, 17h, or 18h.

100 C

90 C

80 C

70 C

60 C

50 C

40 C

TEMP

HIGH LIMIT

LOW LIMIT

ACPI CONTROL

METHODS

CLEAR EVENT

INT

*ACPI AND DEFAULT CONTROL METHODS

ADJUST TEMPERATURE LIMIT VALUES

Figure 22. Operation of

INT for Temperature Interrupts

Once the interrupt has been cleared, it will not be reasserted

even if the temperature remains above the high limit(s). However,

INT will be reasserted if:

a. the temperature falls below the low limit for the sensor

b. the high limit is/are reprogrammed to a new value, and the

temperature then rises above the new high limit on the next

monitoring cycle

c. the

THERM pin is pulled low externally, which sets Bit 5 of

Interrupt Status Register 2

d. An interrupt is generated by another source.

Similarly, should the temperature measured by a sensor start off

within limits then fall below the low limit,

INT will be asserted.

Once cleared, it will not be reasserted unless:

a. the temperature rises above the high limit

b. the low limit is/are reprogrammed, and the temperature then

falls below the new low limit

c. the

THERM pin is pulled low externally, which sets Bit 5 of

Interrupt Status Register 2

d. an interrupt is generated by another source.

THERM INPUT/OUTPUT

The Thermal Management Input/Output (

THERM) is a logic

input/output with an internal, 100 k

Ω pull-up resistor, that

provides a separate output for temperature interrupts only. It is

enabled by setting Bit 2 of Conﬁguration Register 1. The

THERM

output has two operating modes that can be programmed by Bit

3 of Conﬁguration Register 2 (address 4Ah). With this bit set to

the default value of 0, the

THERM output operates in “Default”

interrupt mode. With this bit set to 1, the

THERM output oper-

ates in “ACPI” mode.

Thermal interrupts can still be generated at the

INT output

while

THERM is enabled, but if these are not required they can

be masked by writing a 1 to bit 0 of Conﬁguration Register 2

(address 4Ah). The

THERM pin can also function as a logic

input for an external sensor, for example a temperature sensor such

as the ADM22105 used in Figure 23b. If

THERM is taken low

by an external source, the analog output will be forced to FFh to

switch a controlled fan to maximum speed. This also generates

INT output as previously described.

DEFAULT MODE

In Default mode, the

THERM output operates like a thermostat

with hysteresis.

THERM will go low and Bit 5 of Interrupt Status

sensors exceeds the high limit programmed for that sensor.

It will remain asserted until reset by reading Interrupt Status

the temperature falls below the low limit programmed for that

sensor.

ANALOG

OUTPUT

FFH

CLEARED BY

TEMP FALLING

BELOW LOW

LIMIT

TEMP

HIGH LIMIT

THERM

TEMP

PROGRAMMED

VALUE

EXT

THERM

INPUT

CLEARED BY

READ OR

THERM CLEAR

TEMP

LOW LIMIT

Figure 23a.

INT or THERM Output in Default Mode

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