ADT7482

Rev. 0 | Page 14 of 24

STATUS REGISTERS

The status registers are read-only registers at Addresses 0x02

(Status Register 1) and Address 0x23 (Status Register 2). They

contain status information for the ADT7482.

Table 12. Status Register 1 Bit Assignments

Bit

Name

Function

ALERT

7

BUSY

1 when ADC converting

No

6

LHIGH1

1 when local high temperature limit

tripped

Yes

5

LLOW1

1 when local low temperature limit

tripped

Yes

4

R1HIGH1

1 when Remote 1 high temperature

limit tripped

Yes

3

R1LOW1

1 when Remote 1 low temperature

limit tripped

Yes

2

D1 OPEN1

1 when Remote 1 sensor open

circuit

Yes

1

R1THRM1

1 when Remote1 THERM limit

tripped

No

0

LTHRM1

1 when local THERM limit tripped

No

These flags stay high until the status register is read, or they are reset by POR

Table 13. Status Register 2 Bit Assignments

Bit

Name

Function

ALERT

7

Res

Reserved for future use

No

6

Res

Reserved for future use

No

5

Res

Reserved for future use

No

4

R2HIGH1

1 when Remote 2 high temperature

limit tripped

Yes

3

R2LOW1

1 when Remote 2 low temperature

limit tripped

Yes

2

D2 OPEN1

1 when Remote 2 sensor open

circuit

Yes

1

R2THRM1

1 when Remote2 THERM limit

tripped

No

0

ALERT

1 when ALERT condition exists.

No

The eight flags that can generate an ALERT are NOR’d together.

When any flags are high, the ALERT interrupt latch is set and

the ALERT output goes low (provided they are not

masked out).

Reading the Status 1 register clears the 5 flags, (Bit 6 through

Bit 2) in Status Register 1, provided the error conditions that

caused the flags to be set have gone away. Reading the Status 2

Register clears the three flags, (Bit 4 through Bit 2) in Status

Register 2, provided the error conditions that caused the flags to

be set have gone away. A flag bit can only be reset if the

corresponding value register contains an in-limit measurement

or if the sensor is good.

The ALERT interrupt latch is not reset by reading the status

register. It is reset when the ALERT output has been serviced by

the master reading the device address, provided the error

condition has gone away and the status register flag bits have

been reset.

When Flag 1 and/or Flag 0 of Status Register 1 or Flag 1 of

Status Register 2 are set, the THERM output goes low to

indicate that the temperature measurements are outside the

programmed limits. The THERM output does not need to be

reset, unlike the ALERT output. Once the measurements are

within the limits, the corresponding status register bits are reset

automatically, and the THERM output goes high. To add

hysteresis, program Register 0x21. The THERM output is reset

only when the temperature falls below the THERM limit minus

hysteresis.

When Pin 8 is configured as THERM2, only the high

temperature limits are relevant. If Flag 6 or Flag 4 of Status

Register 1 or Flag 4 of Status Register 2 are set, the THERM2

output goes low to indicate that the temperature measurements

are outside the programmed limits. Flag 5 and Flag 3 of Status

Register 1 and Flag 3 of Status Register 2 have no effect on

THERM2. The behavior of THERM2 is otherwise the same

as THERM.

Bit 0 of the Status Register 2 is set whenever the ADT7482

ALERT output is asserted low. Read Status Register 2 to

determine if the ADT7482 is responsible for the ALERT. This

bit is reset when the ALERT output is reset. If the ALERT

output is masked, then this bit is not set.

OFFSET REGISTER

Offset errors can be introduced into the remote temperature

measurement by clock noise or by the thermal diode being

located away from the hot spot. To achieve the specified

accuracy on this channel, these offsets must be removed.

The offset values are stored as 10-bit, twos complement values.

•

The Remote 1 Offset MSBs are stored in Register 0x11 and

the LSBs are stored in Register 0x12 (low byte, left

justified). The Remote 2 Offset MSBs are stored in Register

0x34 and the LSBs are stored in Register0x35 (low byte, left

justified).

•

The Remote 2 Offset can be written to or read from the

Remote 1 Offset Registers if Bit 3 of the Configuration 1

register is set to 1. This bit should be set to 0 (default) to

read the Remote 1 offset values.

Only the upper 2 bits of the LSB registers are used. The MSB of

MSB offset registers is the sign bit. The minimum offset that

can be programmed is −128°C, and the maximum is +127.75°C.

The value in the offset register is added or subtracted to the

measured value of the remote temperature.

The offset register powers up with a default value of 0°C and has

no effect unless a different value is written to it.