ADT7473 Analog Devices, Inc., ADT7473 Datasheet - Page 15

• Manufacturer Part Number: ADT7473
• Description: Dbcool Remote Thermal Monitor And Fan Controller
• Manufacturer: Analog Devices, Inc.

Table 7. 10-Bit ADC Output Codes vs
V
<0.0042
0.0042 to 0.0085
0.0085 to 0.0128
0.0128 to 0.0171
0.0171 to 0.0214
0.0214 to 0.0257
0.0257 to 0.0300
0.0300 to 0.0343
0.0343 to 0.0386
1.100 to 1.1042
2.200 to 2.2042
3.300 to 3.3042
4.3527 to 4.3570
4.3570 to 4.3613
4.3613 to 4.3656
4.3656 to 4.369
4.3699 to 4.3742
4.3742 to 4.3785
4.3785 to 4.3828
4.3828 to 4.3871
4.3871 to 4.3914
4.3914 to 4.3957
>4.3957
1
TEM
A sim
negati
emitter v
curren
null ou
from device to device.
The t
in V
Previous devices have used only two operating currents, but the
use of a third current allows automatic cancellation of resis-
tances in series with the external temperature sensor.
The V
CC
(3.3 V
BE
echnique used in the ADT7473 is t
PERATURE MEA
CC
ple method of meas
ve temperature coe
t. Unfortunately, t
when the device is operated at three different currents.
t the effect of the
output codes listed a
oltage (V
IN
)
1
9
BE
) of a
his technique re
absolute value o
ssume that V is 3.
fficient of a dio
transistor oper
uring tempera
SUREMENT
CC
V
<0.00293
0.0293 to 0.0058
0.0058 to 0.0087
0.0087 to 0.0117
0.0117 to 0.0146
0.0146 to 0.0175
0.0175 to 0.0205
0.0205 to 0.0234
0.0234 to 0.0263
0.7500 to 0.752
1.50
2.25
2.96
2.97
2.9736 to 2.9765
2.9765 to 2.9794
2.9794 to 2.9824
2.9824 to 2.9853
2.9853 to 2.988
2.9882 to 2.9912
2.99
2.99
>2.9
CCP
. V
ture is to exploit the
o measure the change
ated at constant
3 V.
de, measuring the base-
quires calibration to
00 to 1.5029
00 to 2.2529
77 to 2.9707
07 to 2.9736
12 to 2.9941
41 to 2.9970
f V
970
METHOD
IN
BE
, which varies
9
2
Rev. A | Page 15 of 76
ADC Outp
Decimal
•
•
•
•
•
•
•
•
•
•
•
•
0
1
2
3
4
5
6
7
8
256 (¼ scale)
5
7
101
1
1015
1
1017
1018
1
1
1
1
1
ut
12 (½ scale)
68 (¾ scale)
014
016
019
020
021
022
023
Figure 21 shows the input signal conditioning used to measure
the output of an external temperature sensor. This figure shows
the external sensor as a substrate transistor, but it could equally
be a discrete transistor. If a discrete transistor is used, the collec-
tor is not grounded and should be linked to the base. To prevent
ground noise from interfering with the measurem nt, the more
negativ
is biased above ground by an int nal diode at the D− input. C1
can opt
mum value 1000 pF). However, a better option in noisy
environments is to add a filter, as described in the Noise
Filtering section.
3
e terminal of the sensor is not referenced to ground
ionally be added as a noise filter (recommended m
Binary (10 Bits)
00000000 00
00000000 01
00000000 10
00000000 11
00000001 00
00000001 01
00000001 10
00000001 11
00000010 00
01000000 00
10000000
11000000 00
11111101 01
11111101 10
11111101 11
11111110 00
11111110 01
11111110 10
11111110 11
11111111 00
11111111 01
11111111 10
11111111 11
er
00
e
ADT7473
axi-
, but