ADT7484A/ADT7486A
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
VCC
ADT7484A
2N3904 OR CPU
THERMAL DIODE
1 VCC
2 GND
SST 8
ADD0 7
3 D1+ RESERVED 6
4 D1–
ADD1 5
SST
Figure 17. ADT7484A Typical Application Schematic
2N3904
NPN
VCC
ADT7486A
1 VCC
2 GND
SST 10
ADD0 9
3 D1+ RESERVED 8
4 D1–
ADD1 7
5 D2+
D2– 6
SST
CPU
THERMAL
DIODE
Figure 18. ADT7486A Typical Application Schematic
ORDERING INFORMATION
Device Order Number*
Branding
Package Option
Package Type
Shipping†
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.
http://onsemi.com
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