AT30TS74 datasheet(13/41 Pages) ATMEL

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AT30TS74 [PRELIMINARY DATASHEET]

Atmel-8897D-DTS-AT30TS74-Datasheet_102014

Figure 4-3.

Comparator Mode (Fault Tolerance Queue = 2)

4.4.3

Interrupt Mode

Similar to the Comparator mode, when the device operates in the Interrupt mode, the ALERT pin will go active if

the measured temperature meets or exceeds the high temperature limit set by the THIGH Limit Register and a

valid fault condition exists (the consecutive number of temperature faults has been reached). Unlike the

Comparator mode, however, the ALERT pin will remain active until one of three normal operation events takes

place: any one of the device's registers is read, the device responds to an SMBus Alert Response Address

(ARA), or the device is put into Shutdown mode.

Once the ALERT pin returns to the inactive state, it will not go active again until the measured temperature

drops below the low temperature limit set by the TLOW Limit Register for the appropriate number of consecutive

faults. Again, the ALERT pin will remain active until one of the device's registers is read, the device responds to

an SMBus ARA, or the device is placed into the Shutdown mode.

After the ALERT pin becomes inactive again, the cycle will repeat itself with the ALERT pin going active after the

measured temperature meets or exceeds the THIGH Limit Register value for the proper number of consecutive

faults. This process is cyclical between THIGH and TLOW temperature alarms (e.g. THIGH event, ALERT clear,

TLOW event, ALERT clear, THIGH event, ALERT clear, TLOW event, etc.).

In order for the ALERT pin to normally become active for the first time in the Interrupt Mode, the first event must

be a THIGH temperature alarm event. Therefore, even if the measured temperature initially starts off between the

THIGH and TLOW limits and then drops below the TLOW temperature limit and has met valid fault conditions, the

ALERT pin will still not go active. The high temperature limit set by the THIGH Limit Register must be greater than

the low temperature limit set by the TLOW Limit Register in order for the ALERT pin to activate correctly.

If switching from Comparator mode to Interrupt mode while the ALERT pin is already active, then the ALERT pin

will remain active until it is cleared by one of the events already detailed: any one of the device's registers is

read, the device responds to an SMBus ARA, or the device is put into Shutdown mode. The ALERT pin will also

return to the inactive state if the device receives the General Call Reset command. When reset, the state of the

Configuration Register will return to the power-on default state which will put the device back into the

Comparator mode.

Temperature Measurements/Conversions

THIGH Limit

Temperature

TLOW Limit

ALERT

(Active High, POL = 1)

ALERT

(Active Low, POL = 0)

AT30TS74 Datasheet(PDF) 13 Page - ATMEL Corporation