ADM1030
http://onsemi.com
10
Figure 18. Signal Conditioning
LOW-PASS FILTER
f
C
= 65 kHz
REMOTE
SENSING
TRANSISTOR
BIAS
DIODE
D+
D
V
DD
I
BIAS
I
N ?I
V
OUT+
V
OUT
To ADC
If a discrete transistor is used, the collector will not be
grounded, and should be linked to the base. If a PNP
transistor is used, the base is connected to the D input and
the emitter to the D+ input. If an NPN transistor is used, the
emitter is connected to the D input and the base to the D+
input.
One LSB of the ADC corresponds to 0.125癈, so the
ADM1030 can theoretically measure temperatures from
127癈 to +127.75癈, although 127癈 is outside the
operating range for the device. The extended temperature
resolution data format is shown in Tables 7 and 8.
Table 6. TEMPERATURE DATA FORMAT (LOCAL
TEMPERATURE AND REMOTE TEMPERATURE HIGH
BYTES)
Temperature
Digital Output
128癈
1000 0000
125癈
1000 0011
100癈
1001 1100
75癈
1011 0101
50癈
1100 1110
25癈
1110 0111
1癈
1111 1111
0癈
0000 0000
+1癈
0000 0001
+10癈
0000 1010
+25癈
0001 1001
+50癈
0011 0010
+75癈
0100 1011
+100癈
0110 0100
+125癈
0111 1101
+127癈
0111 1111
Table 7. REMOTE SENSOR EXTENDED
TEMPERATURE RESOLUTION
Extended Resolution (5C)
Remote Temperature
Low Bits
0.000
000
0.125
001
0.250
010
0.375
011
0.500
100
0.625
101
0.750
110
0.875
111
The extended temperature resolution for the local and
remote channels is stored in the Extended Temperature
Resolution Register (Register 0x06), and is outlined in
Table 22.
Table 8. LOCAL SENSOR EXTENDED
TEMPERATURE RESOLUTION
Extended Resolution (5C)
Local Temperature
Low Bits
0.00
00
0.25
01
0.50
10
0.75
11
To prevent ground noise interfering with the
measurement, the more negative terminal of the sensor is not
referenced to ground, but is biased above ground by an
internal diode at the D input. If the sensor is used in a very