Datasheet
ADT7316/ADT7317/ADT7318
Rev. B | Page 22 of 44
Negative Temperatures
128Temp)V(0)(CodeRegisterOffset +=dec
where D7 of Offset Register Code is set to 1 for negative
temperatures.
Example:
()
()
x580d8812840dec ==+−=CodeRegisterOffset
Because a negative temperature is input into the equation, DB7
(MSB) of the Offset Register Code is set to 1. Therefore, 0x58
becomes 0xD8:
()
8xD017DB580 =+x
Positive Temperatures
()
TempV0dec =CodeRegisterOffset
Example:
()
0x0Ad10dec ==CodeRegisterOffset
The following equation is used to work out the various
temperatures for the corresponding 8-bit DAC output:
8-Bit Temp = (DAC O/P ÷ 1 LSB) + (0 V Temp)
For example, if the output is 1.5 V, V
REF
-AB = 2.25 V, 8-bit DAC
has an LSB size = 2.25 V/256 = 8.79 × 10
–3
, and 0 V temp is at
−128°C, then the resultant temperature is
(
)
()
C431281079.85.1
3
o
+=−+×÷
−
The following equation is used to work out the various
temperatures for the corresponding 10-bit DAC output
10-Bit Temp = ((DAC O/P ÷ 1 LSB) × 0.25) + (0 V Temp)
For example, if the output is 0.4991 V, V
REF
-AB = 2.25 V, 10-bit
DAC has an LSB size = 2.25 V/1024 = 2.197 × 10
-3
, and 0 V temp
is at −40°C, then the resulting temperature is
(
)
(
)
()
C75.164025.010197.24991.0
3 o
=−+××÷
−
Table 6. Thermal Voltage Output (0 V to V
REF
-AB)
Output Voltage (V) Default (°C) Max (°C) Sample (°C)
0 −40 −128 0
0.5 +17 −71 +56
1 +73 −15 +113
1.12 +87 −1 +127
1.47 +127 +39 UDB
1
1.5 UDB
1
+42 UDB
1
2 UDB
1
+99 UDB
1
2.25 UDB
1
+127 UDB
1
1
Upper dead band has been reached. DAC output is not capable of increasing
(see Figure 3).
Table 7. Thermal Voltage Output (0 V to 2 V
REF
-AB)
Output Voltage (V) Default (°C) Max (°C) Sample (°C)
0 −40 −128 0
0.25 −26 −114 +14
0.5 +12 −100 +28
0.75 +3 −85 +43
1 +17 −71 +57
1.12 +23 −65 +63
1.47 +43 −45 +83
1.5 +45 −43 +85
2 +73 −15 +113
2.25 +88 0 +127
2.5 +102 +14 UDB
1
2.75 +116 +28 UDB
1
3 UDB
1
+42 UDB
1
3.25 UDB
1
+56 UDB
1
3.5 UDB
1
+70 UDB
1
3.75 UDB
1
+85 UDB
1
4 UDB
1
+99 UDB
1
4.25 UDB
1
+113 UDB
1
4.5 UDB
1
+127 UDB
1
1
Upper dead band has been reached. DAC output is not capable of increasing
(see Figure 3).
Figure 43 shows the DAC output vs. temperature for a
V
REF
-AB = 2.25 V.
TEMPERATURE (°C)
DAC OUTPUT (V)
0
0.15
–128–110 –90 –70 –50 –30 –10 10 30 50 70 90 110 127
0.30
0.45
0.60
0.75
0.90
1.05
1.20
1.35
1.50
1.65
1.80
1.95
2.10
2.25
0V = –128°C
0V = –40°C
0V = 0°C
02661-042
Figure 43. 10-Bit DAC Output vs. Temperature, V
REF
-AB = 2.25 V