ADM1032
Thermocouple effects should not be a major problem as 1°C
corresponds to about 200 V, and thermocouple voltages are
about 3 V/°C of temperature difference. Unless there are two
thermocouples with a big temperature differential between them,
thermocouple voltages should be much less than 200 V.
Because the measurement technique uses switched current
sources, excessive cable and/or filter capacitance can affect the
measurement. When using long cables, the filter capacitor may
be reduced or removed.
Cable resistance can also introduce errors. 1 Ω series resistance
introduces about 1°C error.
5. Place a 0.1 µF bypass capacitor close to the VDD pin. In very
noisy environments place a 2200 pF input filter capacitors
across D+, D– close to the ADM1032.
APPLICATION CIRCUIT
Figure 7 shows a typical application circuit for the ADM1032,
using a discrete sensor transistor connected via a shielded,
twisted pair cable. The pull-ups on SCLK, SDATA, and ALERT
are required only if they are not already provided elsewhere
6. If the distance to the remote sensor is more than 8 inches, the
use of twisted pair cable is recommended. This will work up
to about 6 to 12 feet.
7. For really long distances (up to 100 feet) use shielded twisted
pair such as Belden #8451 microphone cable. Connect the
twisted pair to D+ and D– and the shield to GND close to
the ADM1032. Leave the remote end of the shield unconnected
to avoid ground loops.
i
n the system.
The SCLK, and SDATA pins of the ADM1032 can be inter-
faced directly to the SMBus of an I/O controller such as the
Intel 820 chipset.
0.1ꢂF
V
3V TO 3.6V
DD
ADM1032
TYP 10kꢃ
D+
SCLK
D–
SMBUS
5V OR 12V
SDATA
CONTROLLER
2N3906
OR
SHIELD
ALERT
THERM
CPU THERMAL
DIODE
V
DD
TYP 10kꢃ
GND
FAN CONTROL
CIRCUIT
FAN ENABLE
Figure 7. Typical Application Circuit
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead SO
(R-8)
8-Lead Micro_SO
(RM-8)
0.122 (3.10)
0.114 (2.90)
0.1968 (5.00)
0.1890 (4.80)
8
1
5
4
8
5
4
0.2440 (6.20)
0.2284 (5.80)
0.1574 (4.00)
0.1497 (3.80)
0.122 (3.10)
0.114 (2.90)
0.199 (5.05)
0.187 (4.75)
1
PIN 1
0.0196 (0.50)
0.0099 (0.25)
0.0500 (1.27)
BSC
ꢄ 45ꢁ
PIN 1
0.0256 (0.65) BSC
0.0688 (1.75)
0.0532 (1.35)
0.0098 (0.25)
0.0040 (0.10)
SEATING
PLANE
0.120 (3.05)
0.112 (2.84)
0.120 (3.05)
0.112 (2.84)
8ꢁ
0ꢁ
0.0500 (1.27)
0.0160 (0.41)
0.0192 (0.49)
0.0138 (0.35)
0.0098 (0.25)
0.0075 (0.19)
0.043 (1.09)
0.037 (0.94)
0.006 (0.15)
0.002 (0.05)
6ꢁ
0.015 (0.38)
0.009 (0.22)
0ꢁ
0.028 (0.71)
0.016 (0.41)
0.009 (0.23)
0.003 (0.08)
SEATING
PLANE
–12–
REV. 0
ADI [ ADI ]
