ADT7420UCPZ-R2 datasheet(21/24 Pages) AD

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Data Sheet

ADT7420

Rev. 0 | Page 21 of 24

INT AND CT OUTPUTS

The INT and CT pins are open-drain outputs, and both pins

require a 10 kΩ pull-up resistor to VDD. The ADT7420 must

be fully powered up to VDD before reading INT and CT data.

UNDERTEMPERATURE AND OVERTEMPERATURE

DETECTION

The INT and CT pins have two undertemperature/overtempera-

ture modes: comparator mode and interrupt mode. The interrupt

mode is the default power-up overtemperature mode. The INT

output pin becomes active when the temperature is greater than

the temperature stored in the THIGH setpoint register or less than

the temperature stored in the TLOW setpoint register. How this

pin reacts after this event depends on the overtemperature mode

selected.

Figure 18 illustrates the comparator and interrupt modes for

events exceeding the THIGH limit with both pin polarity settings.

Figure 19 illustrates the comparator and interrupt modes for

events exceeding the TLOW limit with both pin polarity settings.

Comparator Mode

In comparator mode, the INT pin returns to its inactive status

when the temperature drops below the THIGH − THYST limit or

rises above the TLOW + THYST limit.

Putting the ADT7420 into shutdown mode does not reset the

INT state in comparator mode.

Interrupt Mode

In interrupt mode, the INT pin goes inactive when any ADT7420

only when the temperature is greater than the temperature stored

in the THIGH setpoint register or less than the temperature stored

in the TLOW setpoint register.

Placing the ADT7420 into shutdown mode resets the INT pin

in the interrupt mode.

TEMPERATURE

82°C

81°C

80°C

79°C

78°C

77°C

76°C

75°C

74°C

73°C

INT PIN

(COMPARATOR MODE)

POLARITY = ACTIVE LOW

INT PIN

(INTERRUPT MODE)

POLARITY = ACTIVE LOW

INT PIN

(INTERRUPT MODE)

POLARITY = ACTIVE HIGH

INT PIN

(COMPARATOR MODE)

POLARITY = ACTIVE HIGH

HIGH

HIGH – THYST

TIME

READ

Figure 18. INT Output Temperature Response Diagram for THIGH Overtemperature Events

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