ADT7484A/ADT7486A

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11

Temperature Offset

As CPUs run faster, it is more difficult to avoid high

frequency clocks when running the D1+ and D1− tracks

around a system board. Even when the recommended layout

guidelines are followed, there may still be temperature

errors, attributed to noise being coupled on to the D1+ and

D1− lines. High frequency noise generally has the effect of

producing temperature measurements that are consistently

too high by a specific amount. The ADT7484A/

ADT87486A have a temperature offset command code of

0xe0 through which a desired offset can be set. By doing a

one−time calibration of the system, the offset caused by

system board noise can be calculated and nulled by

specifying it in the ADT7484A/ADT7486A. The offset is

automatically added to every temperature measurement.

The maximum offset is

±128°C with 0.25°C resolution. The

offset format is the same as the temperature data format;

16−bit, twos complement notation, as shown in Table 8. The

offset should be programmed in little endian format, that is,

LSB before MSB. The offset value is also returned in little

endian format when read.

Application Schematics

Figure 17. ADT7484A Typical Application Schematic

1

GND

2

D1+

3

D1–

4

SST

8

ADD0

7

RESERVED

6

ADD1

5

ADT7484A

2N3904 OR CPU

THERMAL DIODE

SST

Figure 18. ADT7486A Typical Application Schematic

1

2

3

4

GND

D1+

D1–

D2+

5

10

9

8

7

RESERVED

ADD1

D2–

6

ADT7486A

CPU

THERMAL

DIODE

2N3904

NPN

SST

SST

ADD0

ORDERING INFORMATION

Device Order Number*

Branding

Package Option

Package Type

ADT7484AARZ-REEL

−

R−8

SOIC−8 NB

2500 Tape & Reel

ADT7484AARZ-RL7

−

R−8

SOIC−8 NB

1000 Tape & Reel

ADT7484AARMZ-RL

T20

RM−8

8-Lead MSOP

3000 Tape & Reel

ADT7484AARMZ-R7

T20

RM−8

8-Lead MSOP

1000 Tape & Reel

ADT7486AARMZ-RL

T22

RM−10

10-Lead MSOP

3000 Tape & Reel

ADT7486AARMZ-R7

T22

RM−10

10-Lead MSOP

1000 Tape & Reel

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specifications Brochure, BRD8011/D.

*These are Pb−Free packages.