ADM1032ARM-REEL7 ON Semiconductor, ADM1032ARM-REEL7 Datasheet - Page 15
Manufacturer Part Number
IC TEMP MONITOR 85DEF 8MSOP
Specifications of ADM1032ARM-REEL7
Temp Monitoring System (Sensor)
ADC, Comparator, Multiplexer, Register Bank
External & Internal
0°C ~ 100°C, External Sensor
Voltage - Supply
3 V ~ 5.5 V
0°C ~ 100°C
Package / Case
8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
the ADM1032 is measuring very small voltages from the
remote sensor, so care must be taken to minimize noise
induced at the sensor inputs. The following precautions
should be taken.
Digital boards can be electrically noisy environments, and
Figure 18. Typical Arrangement of Signal Tracks
1. Place the ADM1032 as close as possible to the
2. Route the D+ and D− tracks close together, in
3. Use wide tracks to minimize inductance and
4. Try to minimize the number of copper/solder
5. Place a 0.1 mF bypass capacitor close to the V
6. If the distance to the remote sensor is more than
7. For really long distances (up to 100 feet), use
remote sensing diode. Provided that the worst
noise sources, that is, clock generators,
data/address buses, and CRTs, are avoided, this
distance can be four to eight inches.
parallel, with grounded guard tracks on each side.
Provide a ground plane under the tracks if
reduce noise pickup. 10 mil track minimum width
and spacing is recommended.
joints, which can cause thermocouple effects.
Where copper/solder joints are used, make sure
that they are in both the D+ and D− path and at the
Thermocouple effects should not be a major
problem since 1°C corresponds to about 200 mV
and thermocouple voltages are about 3 mV/°C of
temperature difference. Unless there are two
thermocouples with a big temperature differential
between them, thermocouple voltages should be
much less than 200 mV.
pin. In very noisy environments, place a 1000 pF
input filter capacitor across D+ and D− close to the
eight inches, the use of twisted pair cable is
recommended. This works up to about six feet to
shielded twisted pair, such as Belden #8451
current sources, excessive cable and/or filter capacitance
can affect the measurement. When using long cables, the
filter capacitor can be reduced or removed.
resistance introduces about 1°C error.
Power Sequencing Considerations
Power Supply Slew Rate
the slew rate of V
than this may cause power−on−reset issues and yield
THERM Pin Pullup
requires a pullup to V
be pulled up to the same power supply as the ADM1032,
unlike the SMBus signals (SDA, SCL and ALERT) that can
be pulled to a different power rail. The only time the
THERM pin can be pulled to a different supply rail (other
with, or after the ADM1032 main V
internal circuitry of the ADM1032. If the THERM pullup
supply rail were to rise before V
not operate correctly.
ADM1032, using a discrete sensor transistor connected via
a shielded, twisted pair cable. The pullups on SCLK,
SDATA, and ALERT are required only if they are not
already provided elsewhere in the system.
interfaced directly to the SMBus of an I/O controller, such
as the Intel 820 chipset.
Because the measurement technique uses switched
Cable resistance can also introduce errors. 1 W series
When powering up the ADM1032 you must ensure that
As mentioned above, the THERM signal is open drain and
Figure 20 shows a typical application circuit for the
The SCLK and SDATA pins of the ADM1032 can be
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.
) is if the other supply is powered up simultaneous
Figure 19. Typical Application Circuit
is less than 18 mV/ms. A slew rate larger
. The THERM signal must always
, the POR circuitry may
. This is to protect the
3V TO 3.6V
5V OR 12V